Enchanted Rock: A Natural and Human History 9780292799332

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Enchanted Rock

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NUMBER FIVE

Peter T. Flawn Series in Natural Resources

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Enchanted Rock A Natural and Human History

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L A N CE

A LLR E D

University of Texas Press Austin history

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The Peter T. Flawn Series in Natural Resource Management and Conservation is supported by a grant from the National Endowment for the Humanities and by gifts from the following donors:

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Jenkins Garrett

Sue Brandt McBee

Edward H. Harte

Charles Miller

Houston H. Harte

Beth R. Morian

Jess T. Hay

James L. and Nancy H. Powell

Mrs. Lyndon B. Johnson

Thomas B. Rhodes

Bryce and Jonelle Jordan

Louise Saxon

Ben F. and Margaret Love Wales H. and Abbie Madden

Edwin R. and Molly Sharpe Larry E. and Louann Temple

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Copyright © 2009 by Lance Allred All rights reserved Printed in China First edition, 2009 Requests for permission to reproduce material from this work should be sent to: Permissions University of Texas Press P.O. Box 7819 Austin, TX 78713-7819 www.utexas.edu/utpress/about/bpermission.html ∞ The paper used in this book meets the minimum requirements of ANSI/NISO Z39.48-1992 (R1997) (Permanence of Paper).

Library of Congress Cataloging-in-Publication Data Allred, Lance, 1964– Enchanted Rock : a natural and human history / Lance Allred. — 1st ed. p. cm. — (Peter T. Flawn series in natural resources ; no. 5) Includes bibliographical references and index. ISBN 978-0-292-71963-7 (alk. paper) 1. Natural history—Texas—Enchanted Rock State Natural Area. 2. Geology—Texas—Enchanted Rock State Natural Area. 3. Enchanted Rock State Natural Area (Tex.)—Pictorial works. I. Title. QH105.T4A45 2009 508.764—dc22 2009003361

FACING: Stream Play: The author’s daughters, Sierra (left) and Willow (right), explore a braided Sandy Creek as it flows toward Buzzard’s Roost (in the background).

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This book is dedicated to my wife, Windflower Waters, and my daughters, Willow and Sierra, who allowed me the time for this complex endeavor. It is further dedicated to my mom, Virginia Allred.

{Figure 0.1.1 here}

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Screaming Rock: Weathered boulders can sometimes take on interesting shapes, including faces. This one appears to have a really bad headache.

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Contents

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Acknowledgments Introduction

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PA R T O N E

History 7

PA R T T W O

Geology 39 Weathering and Erosion 71 Weather 93

PA R T T H R E E

Flora and Fauna 123 Plants Trees, Shrubs, and Vines 147 Flowers 153 Cacti and Yuccas 173 Ferns 174 Grasses, Grasslike Plants, Sedges, and Rushes Berries, Seeds, Pods, and Fruit 182 Other Plants 190

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Animals (except bugs) Mammals 197 Birds 199 Reptiles, Amphibians, and Water Creatures 204

Bugs (including arachnids) Butterflies 211 Moths 218 Dragonflies and Damselflies 224 Grasshoppers, Katydids, and Crickets 229 Bees, Wasps, Hornets, and Flies 233 Other Insects 239 Arachnids 248

APPENDICES

A. Historical Timeline

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B. Endemic and Unusual Plants

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C. Enchanted Rock SNA Landmarks and Trails 259

References

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Illustration Sources species Index

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Subject Index

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Weathered Boulders: These few remaining boulders are all that is left of an exfoliation sheet on the east flank of Enchanted Rock Dome.

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Sheltered Areas: Many climbing areas are really jumbles of very large boulders that create sheltered areas, such as this one called Cave-In.

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Preface

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It was the summer of 2005, and I was searching for a book project that could utilize some of the photographs I had amassed over the years. As I thought on the matter and examined the possibilities, I discovered that very little written material was available on Enchanted Rock State Natural Area (SNA), and most of that was out of print, too basic or too broad to do justice to the park, or too technical (such as research papers) for the average visitor. Other than some small pamphlets on hiking up the Summit Trail, and a few Web resources, nothing else was widely available for the roughly 300,000 annual visitors to the park. Enchanted Rock SNA is my favorite park in Central Texas, and maybe it is yours too, if you are reading these words. My initial thought was to capture a body of photographs and produce a coffee-table book showing the beauty of the place, along with some supporting text. Enchanted Rock, however, demands more than just a bunch of pretty pictures. It is an important place in Texas, both historically and today. It has never been covered adequately in print. Why does an area as small as Enchanted

Rock SNA and the broader Llano Region demand such thorough coverage? First, the Llano Region supplies critical clues in the story not only of the geological history of Texas but also for the development of the earth as a whole. Some rock exposures in the Llano Region are considered “classic,” attracting study and interpretation by geologists from around the world. Much new research continues today, increasing our understanding of the earth’s history. Next, the plants and animals that reside in the area consist of an interesting juxtaposition of desert, subtropical, plains, and eastern forest species, including many plants that have been separated from their ranges through long-term climatic change. Enchanted Rock SNA is therefore extremely diverse from a biological perspective. The day-to-day weather in the region helps create conditions that support the variety of plants and animals. Weather in Central Texas most of the time is largely uneventful. However, Central Texas is subjected on a regular basis to prolonged droughts and to some of the most catastrophic flooding in North America, which accelerates the weathering process and reveals geological clues beneath.

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Photographer Shadows: Lance and his wife, Windflower, shoot photographs on Central Texas granite.

Finally, Enchanted Rock SNA is a popular park. Any day of the week finds a line of hikers making their way up the Summit Trail to the top of Enchanted Rock Dome. Enchanted Rock SNA is a mecca for climbers throughout Texas and the South, presenting granite climbing conditions not widely available in the South Central United States. It is so popular that on weekends, the park frequently fills to capacity.

The park and its visitors deserve a single book that provides in-depth coverage, describing the history, geology, and weather. The challenge, as I saw it, was to satisfy the most curious readers with an interesting text, without drowning the work in technical jargon. The balance was struck by using colorful diagrams and photographs with captions to illuminate the complex subject matter. Additionally, review by experts was

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critical, making sure the information was as accurate and up-to-date as possible. On the biological front, traditional fieldguide photographs, including the flora and fauna that reside in the area, would also be useful. Most field guides cover a single topic in depth, such as birds, butterflies, flowers, or reptiles, and then provide cursory coverage of other supporting topics. Some attempt to cover a broad geographic area; they rarely identify more than the most common species of plants and animals within that area. What is missing for Enchanted Rock, though, is a presentation of a wide range of species within this specific location. This book attempts to fill that gap, without getting too large, by describing the park’s biotic communities in brief text summaries along with lots of photographs of individual species. Such a book is more than a field guide; maybe it could be called a destination guide. It touches on all the elements that make Enchanted Rock such an intriguing and endlessly interesting place to visit.

Equipment Used A wide variety of equipment was used to capture and process all of the images in this book. Camera equipment included a Hasselblad 501CX camera with 80mm, 150mm, and 250mm lenses, 2× teleconverter, and

various extension tubes. Also used was a Canon Digital Rebel XT 8 mega-pixel camera utilizing a 70–200mm L IS USM lens, 1.4× teleconverter, 28–105mm USM lens, and various extension tubes. A film-based Canon Elan, with the same Canon lenses, was used for a small portion of the images. Finally, some images were captured with a Sony DSC70 3.1 mega-pixel camera. A Gitzo carbon-fiber tripod was used for all images captured with the Hasselblad and the majority of the other images. Some of the insect and animal images were (reluctantly) hand-held because of the dynamic nature of photography in the field. The film used was Fuji Velvia and Kodak 100GX. The typical jaunt to Enchanted Rock SNA included roughly 30 pounds of equipment, building strong muscles and providing a pleasant, if rather tiring, workout. Film-based images were scanned using the Nikon Coolscan 9000. All images were processed with Adobe Photoshop CS or CS3 Image proofs used by the publisher were made on Epson 7600 and 9800 printers with Ultrachrome inks on Breathing Color Sterling paper. Many of the images in this book are available at http://www.enchantedrocksna. com for purchase. Other images can also be found there. For a wider portfolio of Lance’s images, please see: http://www. planetography.com.

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South American Boulders: These boulders, on the flank of Freshman Mountain, are the remnants of an exfoliation sheet that was quite thick; they are a favorite for climbers.

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Acknowledgments

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I would like to thank my wife, Windflower Waters, for putting up with my time away for frequent visits to Enchanted Rock SNA, for allowing me the long hours before the computer necessary to put a book such as this together, and finally for her feedback on the manuscript. I would also like to thank my twin daughters, Willow and Sierra, for demonstrating patience beyond their age and for their enthusiasm when visiting the park with me. Dr. Leon Long, Professor of Geochemistry at the University of Texas at Austin, was extremely generous with his patience, time, and the materials he provided. His extensive comments and advice were greatly helpful in getting the geology-related material whipped into shape. Thanks to Dr. Long and his colleague Dr. Mark Cloos, Professor of Structural Geology and Tectonics, also at UT, for inviting me to monitor an in-the-field workshop in the Llano Region with one of the UT geology classes, where I learned quite a bit about mapping geological structures. William Carr, biologist for the Nature Conservancy, was beyond generous with the donation of blocks of his time working with me on plant identifications via

photographs, no easy task. Without his help, I would never have been able to make significant progress on the plants. Dr. Troy Kimmel, Chief Meteorologist at KVET/KASE/KFMK Radio (Clear Channel Radio), Senior Lecturer and Manager, Weather and Climate Resource Center, Department of Geography and the Environment, University of Texas at Austin, kindly agreed to review the weather-related materials and provided useful information on historical Central Texas weather. Dr. Sharon Mosher, Professor of Structural Petrology and Tectonics and Department Chair at the University of Texas at Austin, provided key material relating to current research on the events directly related to the creation of Enchanted Rock as part of the development of Rodinia. As stated in the preface, for species identifications, I made an initial identification in most cases and then engaged an expert in the subject to verify my identifications. John C. Abbott, author of the book Dragonflies and Damselflies of Texas and the South-Central United States, was kind enough to look through my dragonfly and damselfly identifications and set me

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straight on those I had incorrectly identified. Please see his Web site at www.odona tacentral.com. John Capinera, coauthor of the book Field Guide to Grasshoppers, Katydids, and Crickets of the United States and Professor and Chairman of Entomology and Nematology at the University of Florida, for looking through my grasshopper, katydid, and cricket identifications and noting any errors. Thomas J. Walker, coauthor of the book Field Guide to Grasshoppers, Katydids, and Crickets of the United States and Professor Emeritus of Entomology and Nematology at the University of Florida, donated his time to verify my katydid and cricket species identifications. Jason Singhurst, Botanist and Plant Community Ecologist with the Texas Parks and Wildlife Department, helped to verify the sedges and rushes. Todd Jackson, a master’s student studying Orthoptera at the University of North Central Texas, helped me further with some grasshopper species. John Stidham provided additional help nailing down the Melanoplus, Trimerotropis, and Arphia genera of grasshoppers. Ed Knudson, M.D., helped with the difficult task of identifying moths, where I made little progress myself.

Valerie Bugh, of www.larvalbug.com, helped to verify the rest of my insect identifications, including bees, wasps, flies, beetles, mantids, and more. She also introduced my girls to some fascinating bugs. Mark Lockwood, of the Texas Parks and Wildlife Department and author of Basic Texas Birds, helped to verify my bird identifications. Joe Lapp (a.k.a. Spider Joe) for his help in identifying arachnids. Other online resources were extremely useful in the identification of bugs and plants. They are listed in the “References” section at the end of the book. Thanks to the Witte Museum in San Antonio for permission to use a reproduction of a Lungkwitz painting, and thanks to David Rumsey for permission to use a reproduction of an Arrowsmith map. The Texshare program was very useful in allowing me to check out materials from the University of Texas Library. In spite of extensive help from professionals who are experts in their fields, it is not out of the question that misidentifications, misstatements, or other errors may have crept into the book. If you find them, please assign the fault to the author. You may contact the author with corrections, or view corrections, by going to the Web site www.enchantedrocksna.com.

FACING: Buzzard’s Roost and North Dome: A view of Buzzard’s Roost from North Dome highlights many unusual features at the park, including gnammas, doughnuts, and exfoliation sheets, along with the beauty of the vegetation in winter.

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Enchanted Rock

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Weathering Pit Panorama: Once water fills a weathering pit, grasses, quillwort, and other plants quickly begin to grow, eventually filling the pit. West Little Rock Dome, Little Rock Dome, and Enchanted Rock Dome are visible in the distance.

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Introduction

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Enchanted Rock—the very name instills curiosity. Looking at the list of Texas state parks, Enchanted Rock Park State Natural Area (SNA) stands out among all of them. Sure, Battleship Texas State Historic Site and Kreische Brewery State Historic Site certainly bring fanciful images to mind. But what comes to mind with Enchanted Rock? Enchanted Rock is not just a mysterious name or marketing campaign by the State of Texas. Enchanted Rock is a place of legends, ancient peoples, Native American ceremonies, New Spain, the Frontier, Republic of Texas heroes in battle, German immigration, silver mines, uranium, and buried treasure! Enchanted Rock—even the origin of its name is more legend than fact. Enchanted Rock is a geological anomaly, as one University of Texas geology researcher put it, “a (fascinating) granite island in a sea of worthless limestone.” Enchanted Rock is a window into the mysterious past of Planet Earth: supercontinents, mountain ranges, epic global flooding episodes, dreadfully long periods with no record at all. Enchanted Rock is a place of biological diversity. The Edwards Plateau, Hill Country, subtropics, Gulf of Mexico, Great Plains, eastern forests, and Chihuahuan Desert all exert their influence.

Enchanted Rock offers a wide range of activities to a broad cross section of outdoor enthusiasts: a climbers’ paradise, hiking, sojourn to the top, birding, camping, and backpacking. Amazingly little has been written about this most popular of Texas parks. Compared with Big Bend National Park in West Texas, with its dozens of books in print at any given time, not one in-print book is available on Enchanted Rock SNA, let alone books that attempt to capture the unique and beautiful landscape and at the same time explain the origins of the park, the actions taking place on it, and the plants and animals found there. How can such an important place in Texas not be better covered?

Book Organization This destination guide has three parts. Part I is a highly selective thread of human history pertaining to the park, the Llano Region, and other areas deemed to be of interest. Part II uses a textbook format to describe the area’s geology, the effects of weathering and erosion, and the weather. The material goes into some depth to satisfy those who want to know more, using

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extensive diagrams and photographs to help demonstrate concepts, but at the same time attempting to keep the text approachable. Part III introduces the flora and fauna, with an emphasis on plant and animal identification through photography, rather than textual descriptions, leaving the heavy lifting of species descriptions to other, more focused works. To identify the important plants and animals, my thought was to use Enchanted Rock SNA as a sort of proxy for the species found throughout the Llano Region. The advantage to this approach is that Enchanted Rock SNA today has been less affected by human activities than some (but not all) private or other public lands, especially since it became a state natural area. It has been studied, it is accessible, and it is beautiful. The Llano Region itself, however, harbors a wide diversity of plants that thrive in various soil conditions, along rivers and near springs, and from east to west, so that the species collected from Enchanted Rock SNA cannot be extrapolated as a record of the species for the entire region. For example, the common sunflower, found throughout the Llano Region, was not found at Enchanted Rock SNA during field work for this book, and the bald eagles that nest along Highway 29 east of Llano are not found at Enchanted Rock SNA. Nevertheless, I believe that the record assembled is quite extensive, more so than that found in any previous single publication. Methodology I visited the park on a regular basis, roughly every three weeks, starting in December

2005 through October 2007, with a few scattered visits after that. During each visit, lasting one to three days, I captured as many plants and animals as possible through photography. As there was so much to see and learn, I found myself shooting from dawn to well after sunset, with an average of something like 700 images a day. Many visits were purposely made not long after rainfall (there were not many of those days in 2006) to discover what new plant and animal life appeared. All plants and animals were photographed in their habitat, with little or no manipulation. The result was well over 35,000 photographs of plants, animals, and general scenery. My original assumption was that it was important to include every species I encountered in the book. If I saw it, another visitor was also likely to see it. The strategy worked quite well for plants and many types of insects, but birds and mammals proved more difficult because special techniques and equipment (blinds, remaining in one place for long periods of time) were necessary to capture them. For plants, the challenge was recognizing new species when I encountered them and photographing the species in a useful manner for recognition by the target audience. During the course of the year, I made a number of “first in county” sightings for Llano and Gillespie counties, and they are being reported to the appropriate interested researchers. The notion of including all species was challenged as the count of plant species approached 350, butterflies almost 60, dragonflies and damselflies 40, birds over 30, plus moths, insects, arachnids, and so on. These species counts are just scratching the

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surface of what is present at the park, especially where insects are concerned. The vast majority of photographs in the book are from Enchanted Rock SNA itself; the handful of exceptions are noted in the list of illustration sources, following “References.” As I am not a botanist, my early photography was centered on capturing species that I noticed and that I determined were different from what I had seen before. During each trip, I made an effort to recapture plants already photographed to record their presence throughout the year. Plant identification was done from the photographs, with an appreciation of the risks of misidentification. As I gained more experience identifying plants, I saw more plants to identify. Some species that do not stand out, however, may have been passed by. The capturing effort was not a survey in the strict scientific sense. The implications of this approach are that many species that may be common, but are still hard to see, may not have been photographed for this book. There are probably massive numbers of mice living at the park, but none was encountered with this technique. Therefore, mice are not included because most visitors will never encounter one (unless you leave food in your backpack for them to find). In the vast majority of the photographs, initial species identifications were done by me during endless hours looking through books and the Web. I generated or acquired species lists from a wide variety of sources, which are listed under “References.” They were invaluable for narrowing down the

possibilities. In some cases, such as moth identification, I made little headway on my own. After I had established some confidence in my IDs, I consulted with experts to verify them. There is some risk in relying on identifications from photographs, and relying on an existing list of species that may or may not be accurate is additionally risky. I tried to be cautious where necessary, and I did not go to the species level of identification if there was some doubt. Although the plants and animals covered in the book are only those found within Enchanted Rock SNA, they should serve as an excellent sampling of those found in the Llano Region. The challenge, as you may be pondering at this point, is to prevent a book like this from bloating to enormous size (and cost) while avoiding compromising it to such a degree that no subject is covered adequately. Another challenge is to make sure that the disciplines are covered accurately and with up-to-date thinking across a broad range of subjects. Probably few people start out with the required diversity and depth of knowledge across so many topics, and any author would have to engage in supplemental study. Consultation with experts in particular fields was a critical part of the process of writing the text. In any multisubject book such as this, compromises have to be made, but they are made with the target audience in mind. I hope you find the compromises made were good ones, and that this book serves you well as you explore one of Texas’ favorite parks, Enchanted Rock SNA. Enchanted Rock SNA—come explore it.

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Split Rock: Split Rock and the nearby Kingdom of Zilch, near the campground, are favorite destinations for climbers.

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History

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Enchanted Rock’s unique appearance, near subtropical climate, and rich variety of animals and plants have attracted people to the area farther back in time than history can probe. Native American peoples lived in Central Texas as long as 13,000 years ago. Habitation and visitation certainly continued into more recent history, as is evidenced by ample artifacts found throughout the area. More recently, groups of Tonkawa, Apache, Comanche, and other Native American groups successively migrated to or through the area from the Great Plains, West Texas, and Mexico. As Spanish explorers arrived and settled in New Spain, the movement of Native Americans accelerated, resulting in massive displacements throughout Texas. Spaniards, at first more focused on solidifying their hold in Mexico, responded to threats of French incursions by establishing a series of presidios and missions in Texas. Drawn by stories related to them by Native Americans and fascinated with the appearance of Enchanted Rock, they explored Central Texas in search of gold, silver, other minerals, and the fabled lands of Quivira. The Spaniards’ inability to project into and

settle the area, along with increasing hostilities with Native Americans, would keep Enchanted Rock at or beyond the edge of the frontier for almost 200 years. By the time of the Republic of Texas, Enchanted Rock was still beyond the frontier, as hostilities continued with the Comanche. Nevertheless, legends played a key marketing role in helping to attract settlers to Central Texas, first under Spanish rule, then Mexican, then Texan, then American. Fredericksburg was founded as part of an immigration scheme operated by a German prince to bring Germans to Texas. The German negotiations for peace with the Native Americans finally brought some stability to the area, but violence continued to flare up occasionally into the 1870s. Stories and legends abound in the various cultures surrounding Enchanted Rock. The strange-looking landforms convinced many individuals that massive mineral wealth was present in the area, often lost, buried, and yet to be rediscovered. Other stories of haunted stone hills, strange noises, ghosts, and tales of human sacrifices intensified the mystery surrounding the place.

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Enchanted Rock has been claimed as the territory of Spain, France, Mexico, the Republic of Texas, the Confederate States of America, and the United States of America, not to mention the Native American peoples who claimed the area as their hunting grounds. The park itself has seen thirteen owners, including the latest, the State of Texas. Not bad for 1,643 acres of granite!

Archaeological Periods People have inhabited Central Texas for at least the last 13,000 years. That habitation can be divided into five periods: PaleoIndian, Pre-Archaic, Archaic, Prehistoric, and Historic. The Paleo-Indian Period spanned roughly 3,000 years, from 11,000 to 8000 BCE. At the beginning of the period, the most recent ice age was coming to an end. Temperatures were cooler and the climate wetter than today. A poorly understood group of people known as the Clovis inhabited many areas in North America. Their ancestors probably crossed the land bridge that connected Siberia to Alaska. They, and possibly other groups coming to America, subsequently made their way across all of North, Central, and South America. The Clovis would have hunted or utilized animals that are now extinct, such as American species of elephant, camel, and horse. The Gault Site in Bell County, a little north of the Llano Region, not only has evidence of the Clovis but also contains a record of habitation for more than 11,000 years. The Nightingale Archaeological Site near Marble Falls contains a similarly rich

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record of habitation extending back to the Paleo-Indian Period. By 9200 BCE, much of the large Ice Age fauna were gone. During the remaining Paleo-Indian Period and through the Archaic Period, Native Americans in Central Texas consisted of small bands of hunters who pursued bison and other smaller game. They are referred to as the Llano Complex. They frequently migrated as game and other food sources were depleted in a given area. Small pottery, unusual for hunter-gatherers, was created to help with cooking. Other artifacts that have survived include points (dart and arrow) and debris in middens. Archaeological evidence for all of the periods has been found at Enchanted Rock SNA. In the Pre-Archaic Period (8000–5500 BCE), a dearth of artifacts indicates a possible decline in population. Maybe the decline had something to do with the drying and warming of the climate, the extinction of Ice Age fauna, or some other reason. The Archaic Period (5500 BCE–800 CE) saw a major uptick in Native American activities in Central Texas. The period can be broken into a number of smaller units: Clear Fork (5500–4000 BCE), Round Rock (4000–2600 BCE), San Marcos (2600–2000 BCE), and Twin Sisters (2000 BCE–700 CE). A habitation area can often be dated and classified to a particular interval through examination of spear, dart, and arrow points. The construction method and shape of these stone objects changed over long periods of time. Styles of points found include Fairland, Ensor, Frio, Pedernales, Bulverde, Nolan, Scottsbluff, and Plainview,

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Stone Points: The style of a point can help determine when it was made, along with its primary use.

each representing a specific construction style and therefore time period. Archaic people hunted modern-day animals and harvested plants. Rock shelters were occasionally used. Petroglyphs and pictographs from that time have been found in numerous locations around Texas, such as the roughly 4,000-year-old pictographs found at Seminole Canyon and throughout the lower Pecos River. Dart points, bifaces (sharp-edged tools for cutting and scraping skins), metates (bowlshaped stones to grind grain in), manos (pestlelike stones for crushing acorns, walnuts, roots, mesquite seeds, and bulbs),

and bedrock metates or mortars (depressions on rocks where food can be smashed or ground) were created and used. Burned middens (trash piles) were widespread. Semipermanent or permanent camps were established where small groups lived together. During the Prehistoric Period (800-1700 CE), Native American populations began to resemble their modern-day organization. The period has three divisions: Austin (800–1200 CE), Toyah (1200–1400 CE), and post-Toyah (1400–1700 CE). Early in the Austin phase, the bow and arrow came into use, allowing for much greater hunting success. Subsequently, larger populations could be supported. Many camps have been found in Central Texas, including at Enchanted Rock SNA. Bison herds numbered in the thousands, and other game were hunted around Enchanted Rock SNA. Some small groups engaged in primitive

Pictograph: Pictographs are found in West Texas and along the Rio Grande. A few can be found in the Llano Region. This particular one was captured at Devils River State Natural Area.

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farming. The Toyah phase saw an increase in trade and possibly conflict between Native American peoples. For unknown reasons migrations increased, especially from the Great Plains into Central Texas. At the end of the Prehistoric Period, the Spanish arrived on the scene and began to have profound effects. Artifacts acquired from the Spanish began to appear. Pictographs at Seminole Canyon in South Texas show people on horses with hats. Migrations and unrest increased. The Historic Period started from approximately 1700 CE, as Spaniards moved in greater numbers into Central Texas and began to record what they encountered. More than 300 sites are located across Llano County and more than 100 sites are in Gillespie County. The Lehmann Shelter, in northeast Gillespie County, contains pictographs dating to sometime at the end of the Prehistoric Period. At Enchanted Rock SNA alone, more than 100 sites have been found, with the majority dated to the Archaic Period. The Spencer Site, near the park’s present-day visitor center, yielded an extensive collection of points, pottery sherds, hearths, burned rock middens, and other artifacts from multiple time periods. More than 12,000 artifacts, mostly lithic scatter, were found during archaeological excavation at that site alone, along with 131 tools. This large body of artifacts was discovered even though amateur collectors had extensively probed the area for decades before the creation of Enchanted Rock SNA. Other items found in or around the park include bedrock mortars, grind stones (metates and manos), bifaces, and flint, which probably originated from the nearby

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Bedrock Mortar: Bedrock mortars are created when a mano (a hand-sized stone) is used to grind grain in a natural rock depression. Over time, the depression becomes deeper, making the bedrock mortar more effective and polished from the grinding action.

Pedernales River (“pedernal” means flint in Spanish). Many Enchanted Rock SNA sites reside near Sandy Creek or Walnut Springs Creek. Other sites were found around the periphery of the granite domes. Unlike other Texas locations, less evidence is found on the top of the granite domes or in the many crawl spaces and caverns at the park. There are no known Enchanted Rock SNA petroglyphs or pictographs, such as those found at Seminole Canyon, Devils River SNA, Hueco Tanks State Historical Site, or other minor sites closer to Enchanted Rock SNA. Before Enchanted Rock became a state park, the land had been under private ownership since the early nineteenth century, and it was operated as a private park from

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the 1920s. As was the culture of the time, the collection of artifacts was allowed and encouraged to promote visitation. Unfortunately, large quantities of artifacts were removed by visitors, many never to be seen again. By the time of the 1970 surveys, many of the important archaeological sites had been greatly disturbed. On the other hand, some of the early families who owned property in and around Enchanted Rock or who visited the park had assembled collections of artifacts that remained intact and have been studied by archaeologists. Between the Moss, Welgehausen, and Spencer collections and the surveys in the late 1970s, 622 points from 96 different sites (some outside but near the park boundaries) were studied, revealing a great diversity of points from all of the major time periods. Collections also include pottery sherds, various tools, and other artifacts, along with bison, deer, and other animal bones. Survey work in 1979, prior to the area’s becoming a state park, was used as a basis to demonstrate the area’s archaeological importance. The study led to the establishment of the Enchanted Rock Archaeological District in 1984, which was added to the National Register of Historic Places. The designation recognizes Enchanted Rock’s importance as both a prehistoric and historic place of significance. Today, the most visible signs of the previous presence of Native Americans are a few bedrock mortars and the remote possibility of encountering a point or grinding stone. Any findings should be left in place and reported to park staff, as was the biface tool found by my daughter.

Early Spanish Expeditions Spaniards explored Texas and other New World locations with four primary goals: extending the empire, exploiting mineral wealth, checking the expansion of the British, French, and other European powers, and civilizing and converting the native populations to Christianity. Spanish expeditions visited the Texas Gulf Coast as early as 1519. Starting from Jamaica, Alonso Álvarez de Pineda explored from Florida to Veracruz, Mexico, searching for the fabled Strait of Anián, a sea route to Asia. He met up with Hernán Cortés, who had set up a base at Villa Rica de la Vera Cruz. In 1528, the Pánfilo de Narváez expedition explored the western coast of Florida. After hostilities broke out with the Native Americans, the expedition built barges and fled into the Gulf of Mexico, where a month later they were caught up in a storm near the mouth of the Mississippi River. The storm carried 79 survivors to the Texas coast near Galveston Island. After initial friendly contact with the Karankawa, the Native Americans turned hostile. Much of the remaining expedition fled south, never to be seen again. Álvar Núñez Cabeza de Vaca, who had stayed behind, met up with three members of his expedition. They subsequently took a circuitous route to reach Culiacán, Mexico, eight years later, in 1536, where they related their story to Melchor Díaz, Francisco Vázquez de Coronado, and Antonio de Mendoza, viceroy of New Spain. Based on Cabeza de Vaca’s accounts, numerous expeditions were launched

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Spanish Exploration Routes: A selection of Spanish expeditions across Texas includes the earliest expeditions and those traveling near the Llano Region.

soon thereafter. Coronado, departing from Mexico City, would explore modern-day New Mexico, the Panhandle of Texas, Oklahoma, and Kansas, searching for, among other things, Cibolo and Quivira, two of the fabled Seven Cities of Gold. He retreated after hostilities broke out with Native American populations in Kansas. From 1539 to 1543, Hernando de Soto’s expedition, originating from Cuba, explored a wide-ranging area of today’s southeastern and midwestern United States. In 1542, soon after de Soto’s death, his expedition, now led by Luis de

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Moscoso, entered Texas. During their travels, they encountered the Taysha people, where the name “Texas” originated (“Tejas” in Spanish). The expedition continued to Central Texas, reaching the future site of San Antonio and exploring the South Llano River near today’s Junction. The early expeditions had some common experiences. They found a vast land, but no passage to China. They found vibrant Native American cultures, sometimes residing in large communities. They heard rumors of fabulous cities, waterways, and mineral wealth in faraway places. And their

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interactions with the Native Americans ranged from partnership to hostile. Eventually, Native American populations were decimated by smallpox, cholera, and other diseases brought by Europeans. Estimates range from 50 percent to as much as 95 percent mortality in some groups. Many Native American peoples came to associate their arrival with a mortal threat, requiring war to protect them.

Native American Populations at Spanish Arrival Native Americans did not utilize written languages; they relied on stories to pass oral histories from generation to generation. Our notion of the location of Native American populations in Texas in the 1500s and 1600s comes from records left by the Spanish as they interacted with the shifting and splintered populations. For example, the Apache are important to the history of Texas, but they actually consisted of numerous independent groups who shared cultural and linguistic characteristics. Typical groups may have consisted of dozens or hundreds of individuals. They were known by such names as “Lipan,” “Jicarillo,” “Mescalero,” “Kiowa,” and others. Many of these names reflect the organization of Native Americans in the 1700s, which had undergone some profound changes since the 1500s and 1600s. Spanish confusion made it difficult for the explorers to determine who was friend and who was foe. The ongoing lack of knowledge of the political and cultural organization of Native American peoples would plague the Spanish throughout their New World empire.

Large herds containing thousands of bison moved in and out of Central Texas on their annual migration. Many Native American groups migrated along with the bison herds, often leading to conflict over hunting grounds and rights. By the mid1700s, the herds were greatly reduced in number, whether through hunting, better weapons acquired by the Native Americans through trade, or some other causes. As the bison numbers dwindled, many Native American populations became increasingly dependant on the Spaniards for support. The Tonkawa were in place around Enchanted Rock and other Central Texas locations when Spaniards started exploring the area. It is not clear when the Tonkawa arrived at Enchanted Rock. It could have been as late as the mid-seventeenth century, just as the Spaniards were launching their first expeditions into Central Texas, or they may have arrived earlier. The Tonkawa consisted of the Mayeyes, Cava, Cantona, Emet, Sana, Toho, Tohaha, and other subgroups. They hunted buffalo and other large and small game. Many of the Tonkawa groups combined in the late eighteenth century in an attempt to stave off annihilation by Apache and later Comanche groups. One subgroup of the Tonkawa, known as the Chana, may have been the specific band of Tonkawa in and around Enchanted Rock; they are most likely the origin of the name “Llano.” Around 1716, the Llano River was known to the Spanish as the Rio de las Chanas or, alternatively, the Rio de los Llanes. Much of the evidence of Native Americans at Enchanted Rock SNA, such as the manos, metates, arrow and dart points, and

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North American Migrations: Arrival of the Spanish, and infiltration by Apache and Comanche from the Great Plains and other Native American groups displaced from the eastern United States, greatly affected the Texas Native American population as understood around 1500. On the diagram, yellow labels indicate cultural affiliations, white labels selected groups, and pink labels the Apache and Comanche.

burnt rock middens, is from the Archaic Period, which predates the Tonkawa.

Shifting Populations and Alliances Many Native American peoples desired to trade with the Spaniards. The Spaniards brought horses (species endemic to North America had been extinct for thousands of years), guns, and other western goods. Native Americans wishing to trade with the Spaniards traveled to their cities in modern-day Mexico, New Mexico, and Texas.

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The Jumano, who ranged into the western Edwards Plateau, had good relationships with the Spanish in the early and mid-seventeenth century and led the Spanish on many an expedition. By 1680, the Spanish had reached as far as Northeast Texas and initiated contact and trade with the Caddo nation and other plains cultures. The Apache originated in the High Plains of Colorado. These loose bands of seminomadic people hunted game and occasionally engaged in farming. There were three major Apache subgroups, the

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Lipan, Mescalero, and Jicarillo. Sometime in the mid- to late seventeenth century, the Apache began to migrate in greater numbers. Their motivation is not known for certain. The Apache may have been displaced by the Comanche, expanding their bison hunting range, or moving closer to the Spanish for trade. The Mescalero and Jicarillo Apache moved (or were pushed) into West Texas and New Mexico. The Lipan Apache drifted into Central Texas. By the early to mid-1700s, Lipan Apache had filtered into the Enchanted Rock area, where they largely displaced the Tonkawa. To date, the Tonkawa had been quite hostile toward the Spanish, but now they sought an alliance to help defend against the encroachment. The Tonkawa began migrating south toward the Spanish missions and presidios at San Antonio and east toward the future location of Austin. The Comanche consisted of bands of nomadic people who originated in present-day Wyoming. By 1650, they were migrating down through Colorado and into North and West Texas. They eventually established a firm presence in the Escalante in the panhandle of Texas. They followed their primary food source, High Plains bison, on their annual migrations. By the mid to late 1700s, small bands of Comanche, such as the Penateka, had migrated deep into Central Texas. Just as the Tonkawa were displaced from Enchanted Rock by the Lipan Apache, in turn the Lipan Apache were displaced by the Comanche. Other displaced small bands from the Arapaho, Waco, Caddo, Tehuacana, Wichita, Kiowa, Cheyenne, Delaware, Shawnee, Cherokee, and others from a wide range of

original locations could also be found in and around Enchanted Rock and throughout Texas. The 1750s saw the Tonkawa and Lipan Apache united with the Spanish to defend against the incoming Comanche. The complex set of shifting alliances, skirmishes, and all-out wars between the various Native American peoples made it quite difficult for the Spanish to project power into Central Texas.

Missions and Presidios In 1685, Frenchman René-Robert Cavelier, Sieur de La Salle, arrived in Matagorda Bay and set up Fort St. Louis. The establishment of French colonies in Texas was completely unacceptable to the Spanish Crown, which moved aggressively to assert its sovereignty over Texas. The Spanish actively pursued any rumors of French traders or colonists in Texas. By the time the Spanish found Fort St. Louis, it had been abandoned after starvation, disease, conflict with the Native Americans, and rebellion. The later establishment of New Orleans in 1718 by the French would demonstrate just how weak the Spanish position was in the New World. An uprising in 1680 in modern-day New Mexico greatly weakened the Spanish position there, and the news of Fort St. Louis deepened the sense of crisis. The Spanish set out to consolidate their position in the northern part of their New World territory. Dozens of missions and presidios (forts) were established throughout Texas from 1680 to the latter half of the 1700s. The intention was to bring the

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Spanish Missions and Presidios: The Spanish built missions and presidios, or forts, across today’s Mexico, New Mexico, and Texas to project and protect their interests. The success of the missions was checked by disease, hostile or indifferent Native American populations, and the French. The Mission Santa Cruz de San Sabá, just northwest of Enchanted Rock, succumbed to Native American attacks soon after it was established. Missions are marked by red dots, presidios by yellow squares.

Native Americans into missions, civilize and convert them, and utilize the native populations to assist with the extraction of mineral wealth. The first missions were those along the Rio Grande near modern El Paso, relocated as a result of earlier troubles in New Mexico. Other early missions were set up in Northeast Texas, including the Mission San Francisco de los Tejas in 1690. The Presidio San Antonio de Béjar and Mission San Antonio de Valero were founded in 1718, in part to serve and protect members of the Coahuiltecan, Jumano, and Tonkawa tribes who were displaced by the incoming Lipan Apache and later Comanche. Between 1746 and 1749, the Spanish established three missions along the San Xavier (San

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Gabriel) River to the south of Enchanted Rock for the Tonkawa.

Exploration around Enchanted Rock The Spanish, led by Jumano guides, made documented excursions to the south and west of the Enchanted Rock area as early as the 1690s. The so-called Pinto Trail ran up from modern-day San Antonio along today’s U.S. Highway 281, passing by the future location of Fredericksburg before continuing past Enchanted Rock, along today’s Ranch Road 965, and onward to the northeast. In June 1753, Lt. Juan Galvan traveled from the Presidio de San Antonio de Béjar past the Pedernales and Llano rivers

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looking for a location to establish a mission as a buffer against attacks on San Antonio by Comanche and other Native Americans and to serve the Lipan Apache. The Lipan Apache reported a tremendous hill of silver, which the Spanish named Cerro del Almagre (Hill of Red Ochre), in Comanche territory north of San Antonio. Don Bernardo de Miranda y Flores, a lieutenant general, departed San Antonio in February 1756 with a group of 28 to explore El Lomeria (the Hill Country) for gold and silver. His preserved daily logs note the rivers his party crossed, including the Rio del Alarcon (Guadalupe), Rio del San Antonio de Ahumada (Blanco), Arroyo de los Pedernales (Pedernales), Arroyo de San Miguel (Sandy Creek), Rio de las Chanas (Llano River), Rio del San Miguel (Honey Creek), and Rio Colorado (Colorado). He found a cave at Cerro del Almagre, which he named Cava del San José del Alcazar, and collected samples of what was thought to be silver. (It would later be known as the San Sabá or Los Almagres mine.) While possibly reconnoitering the Riley Mountains for silver and gold, Miranda y Flores reported seeing the Hill of the Sacred One, a name he probably heard from the Native Americans. He called it Cerro de Santiago. Although its location is not certain, a careful reading of his logs leads many to believe that “Cerro de Santiago” is a reference to Enchanted Rock. Miranda y Flores’s enthusiastic report of silver veins, along with his samples, was to be the key factor creating rumors and legends of fabulous wealth in the area. Testing of the samples, however, showed that little

silver was present. Nevertheless, in 1756 a site for a new mission was chosen on the San Saba River to the north of Enchanted Rock. The Mission Santa Cruz de San Sabá (San Sabá Mission) was completed in 1757 to serve the Lipan Apache in the area. In conjunction, the Presidio San Luis de las Amarillas (San Sabá Presidio) was built nearby to protect the mission. The Apache, in reality, probably agreed to the mission for political reasons in an attempt to pit the Spanish against their Comanche enemies. In its short lifetime, the mission never saw any sizable residence by Apache. The alliance of the Spanish with the Lipan Apache was pivotal in turning many Native American groups against the Spanish. On March 16, 1758, the Norteña (a band of 2,000 strong, drawn from fragmented independent groups representing many nations), attacked the San Sabá Mission and Presidio using weapons acquired from the French. The mission was destroyed, but the presidio, four miles away, was able to withstand the attacks. The Spanish organized retaliatory attacks, one led by Col. Diego Ortiz Parrilla in 1759 on the Taovaya (a branch of the Wichita) against a fort built by the Native Americans near the Red River. The fort had entrenchments, walls, and a moat, and it flew the French flag. His inability to capture the fort further exposed the weak position of the Spanish. The Spanish maintained the San Sabá Presidio until 1769, when they finally abandoned it. Periods of peace and attacks continued until 1784 as combinations of Native Americans attacked the Spanish. In 1784 El Mocho, a leader of the Native Americans,

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was killed. This led to a relatively peaceful period for some time, but the Spanish were never able to reestablish firm control around and north of Enchanted Rock again. Enchanted Rock moved from being at the edge of the frontier to beyond it. In 1810, a heavily armed Spanish expedition led by Lt. Juan Padilla determined that there was adequate silver at the Los Almagres mine to restart operations. By 1812, heavily armed Spanish parties were once again attempting to mine silver in the San Saba area, with little or no success.

Immigration through Empresarios The Spanish New World government established an empresario system to help attract settlers to their lands. Well-connected individuals or groups negotiated empresario colonization contracts. Each contract consisted of a large block of land put under the management of an empresario manager who promoted immigration into the assigned area. Each immigrant head-ofhousehold had the right to purchase land from the empresario manager. Settlers were required to reside and farm their plot of land for a period of time before they could purchase the land. If the empresario manager met the immigration targets negotiated in his contract with the Spanish authorities, he would be allowed to purchase land for a heavily discounted price. After Mexican independence was gained in 1821, the Mexican government continued the Spanish policy but opened it up to a much wider range of settlers. Moses Austin, who had been negotiating with the Spanish, was awarded an empresario colonization

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contract in 1821, but died soon thereafter. His son, Stephen F. Austin, established Austin’s Colony across a broad swatch of land stretching from East to Central Texas. In 1824, he also founded San Felipe de Austin (also known as San Felipe) as the capital of his colony in 1824 along the banks of the Brazos River in Southeast Texas. By 1825, Austin had brought 300 families to his colony. By 1832, there were 11,000 Anglo-Texans in the colony. One enticement that Austin used to promote Central Texas was the promise of silver mines and mineral wealth, based on stories of Spanish mines in the Enchanted Rock area. In 1829, under the authority of Austin, a group led by Capt. Henry S. Brown explored the area and formally recorded Enchanted Rock. He is often called the discoverer of Enchanted Rock, being the first Anglo-Texan to write about the place, but as we know, Enchanted Rock had been known to the Spanish for at least 70 years and to the Native Americans for thousands of years.

Conditions of War The 1803 Louisiana Purchase brought large swaths of land formerly under French sovereignty to United States control, removing the buffer between the United States and New Spain in Texas. The relentless westward movement of explorers and settlers through Tennessee, Ohio, and other states now reached into the Louisiana Purchase area and onward into Spanish-controlled Texas. The influx of immigrants became a flood. The empresario system was highly effective in attracting settlers, mostly Americans,

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to Texas. At first, Spanish and later Mexican empresario land grants in Texas absorbed the growing influx of Americans. As immigration accelerated, Mexican politicians grew increasingly concerned about their ability to control the immigrants. The Fredonian Rebellion occurred in 1826–1827, when Haden Edwards and his brother, land-grant agents for a tract near Nacogdoches, used title conflict as an issue in an attempt to break away from Mexican rule. Their attempt was squashed by the Mexican army. In 1830, the Mexican Congress passed a law prohibiting further immigration of Americans into Texas, as the settlers now outnumbered Mexicans by roughly three to one. Tariffs were imposed, which greatly limited the ability of the Texans to trade. Mexican troops were sent to control immigration along the porous border, but the law and the enforcement efforts were not effective in stopping immigration into Texas. In 1833, Stephen F. Austin traveled to Mexico with the goal of getting the immigration ban lifted and the tariffs removed, and he engaged in discussions of Mexican statehood for Texas. After his meetings, he was arrested for insurrection and held for six months under various forms of house arrest. That same year, Antonio López de Santa Anna was elected president of Mexico. In 1835, after a failed attempt to root out corruption by his vice president, Santa Anna suspended the Mexican Congress and greatly centralized power. Many of the Mexican departments (states) and territories, including Texas, went into rebellion. That same year, Santa Anna attempted to impose a new constitution on the Mexican

territories. The constitution removed the rights of freedom of religion, thought, and the press, and removed the right to hold slaves. By late 1835, the situation had deteriorated greatly for Mexico. The government’s hold on its states was tenuous at best. Anglo-Texans were calling for secession. Only the San Antonio and Goliad missions remained under Mexican control. Others had long been abandoned. Action had to be taken. Conflict and war would soon follow.

Republic of Texas Anglo-Texan settlers, like any settlers across the United States, were well armed. In October 1835, Mexican troops attempted to confiscate weapons (specifically, a cannon) from the settlers at Gonzales. The Anglo-Texans fought back, and general war broke out. By November 15, 1835, the Anglo-Texans had established the Texas Provisional Government with Henry Smith as governor. As fighting intensified between the Texans and Mexicans, the Texans held a convention at Washington-on-the-Brazos on March 1, 1836, to draft a constitution. The delegation signed a declaration of independence on March 2. Just before and after this event, the famous siege of the Alamo was taking place, from February 26 to March 6, 1836. On March 16, 1836, an ad interim government was established, with Sam Houston elected commander-in-chief and David G. Burnet president. By the next day, members of the convention were fleeing Mexican troops led by Santa Anna.

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Within a month, on April 21, 1836, the Texas settlers defeated Santa Anna’s army at San Jacinto. Treaties were signed with Santa Anna at Velasco on May 14, 1836, establishing the Rio Grande as the border between Texas and Mexico. Although Santa Anna was ousted as president, the subsequent Mexican government continued to pump military supplies into the area. By June 1836, the Mexican government had repudiated the treaties signed by Santa Anna and sent more troops north of the Rio Grande. Low-grade hostilities would continue into the 1840s. Santa Anna would return as president in 1838 during a time of chaos in Mexico and as a result of attacks by the French. In the spring and summer of 1836, Texas government officials sought recognition of the Republic of Texas from the United States. An election was called for September 1836, and Sam Houston won the vote for president. He was inaugurated on October 22, 1836, as the president of the Republic of Texas with the expectation that he would aggressively seek recognition of the independence of Texas. On March 1, 1837, the United States granted diplomatic recognition and appointed a charge d’affaires representative to be located in Texas. Great Britain recognized the Republic of Texas on November 16, 1840. In February 1836, Houston signed a treaty with Native Americans, including the Quapaw, Choctaw, Biloxi, Alabama, Coushatta, Cherokee, Shawnee, Delaware, Kickapoo, and Caddo, to establish a reservation over a broad area of land bounded by the Angelina, Neches, and Sabine rivers and the Old San Antonio Road. The period from 1836 through 1840 saw 20

continued unrest throughout Texas. Mexican attacks and Native American uprisings and skirmishes made life for immigrants, especially beyond the frontier, very dangerous. The area around Enchanted Rock SNA was one where settlers dared not go except in heavily armed groups. Native Americans, primarily Comanche, protected the area fiercely. President Mirabeau Lamar succeeded President Houston in 1838. Lamar used aggressive policies to push the Native Americans north and west and the Mexicans south with the intent that Anglo-Texans would fill the void. He signed numerous bills to encourage massive immigration and settlement of Texas. The sheer vastness of Texas, at 251,579,800 acres, meant that the area could support immigration for a long time. Land was the only asset Texas had, and land sales were a way to raise revenue. One bill, signed on January 1, 1840, allowed for establishment of empresario colonization contracts similar to those introduced by the Spanish. Heads of families (African Americans and Native Americans excepted) living in Texas on March 2, 1836, could apply for a square league (4,428 acres) plus a labor (177.1 acres) of land in what was known as a headright certificate. Single men over age seventeen could receive one-third of a league. Immigrants arriving between March 2, 1836, and October 1, 1837, received a grant of 1,280 acres. The Texas Congress reduced the amounts to 640 acres and 320 acres, respectively, to heads of family, veterans of the Texas Revolution, and single men arriving after October 1, 1837, and before January 1, 1842. More changes in the kind of grants allocated would result in

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serious problems with land titles throughout Texas that continue today. A land grant did not convey ownership. To gain ownership of a tract of land, the applicant had to patent the grant by fulfilling certain criteria. The man or family had to reside on the land for a period of time (three years if arriving in 1836) and cultivate a certain percentage of acres. Land had to be purchased for 50 cents per acre once the terms of the grant were fulfilled. Consequently, many grants of land were never patented by the first grantee, including the first grant of land encompassing Enchanted Rock SNA. Lamar’s policies toward the Native Americans, along with other fiscal challenges, required spending large sums of money. The Republic of Texas was bankrupt when Sam Houston was reelected for a second term, in 1842. Houston attempted to establish stability with the Native Americans through treaties, but he continued Lamar’s colonization efforts. Texas was still land rich, cash poor, and debt-ridden. Annexation to the United States or Mexico was a way to stabilize its finances. As a negotiating tactic, a truce agreement with Mexico was declared by Houston on June 15, 1843; a permanent armistice was signed on February 18, 1844. Texas would ultimately be part of the United States. During the 1830s and early 1840s, the area in and around Enchanted Rock was just beyond the frontier of European settlement. The area had been controlled by Native Americans since the Spanish abandoned it in the 1770s. Bands of Comanche and small units from other tribes harassed travelers to the area, including around

Enchanted Rock. The Native Americans saw surveyors as an advanced guard for the settlers to follow, and they believed the survey devices were somehow stealing their land; they were pursued vigorously.

German Settlement Visitors to Fredericksburg and the Enchanted Rock SNA vicinity may notice a multitude of Germanic names. How did this come to be? It turns out that the area, and much of East and Central Texas for that matter, was the focal point of one of many interesting immigration schemes in the history of the United States. Waves of German settlers brought Western civilization to the Enchanted Rock area after more than 100 years of effort by the Spanish, Mexicans, and American-born Texas settlers. The influx of Germans to Texas arose from increasing unrest in the 1830s and 1840s in German lands. Attempts by elements of German nobility to create a modern cohesive nation state, as other major European powers had done, had been frustrated, leaving Germany a collection of fiefdoms under the control of outside powers. The German Confederation was seizing property and land holdings from the nobility. In 1840, the French Parliament openly discussed annexing German lands along the Rhine. Simultaneously, news of the struggles taking place in Texas was followed with great interest throughout Europe. Liberal immigration laws enacted by Mexico and then continued by the Republic of Texas encouraged Germans to immigrate. Many prominent German settlers already in East Texas reported favorable conditions. Some history

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even had grand dreams of establishing a German republic in the heart of Texas. Against this backdrop, 21 princes, barons, dukes, and counts met at Biebrich am Rhine in April 1842 to form the Mainzer Adelsverein (Society of Noblemen). The purpose was to promote large-scale immigration to Texas through outright land purchases. They elected Count Karl von Castell as president. Count Joseph de BoosWaldeck and Count Victor zu Leiningen would be sent to Texas to scout the land and assess the situation. After an initial scouting mission, meetings with President Houston and other Republic officials, and a report back to Germany, the group warmed to the alternate concept of colonization contracts offered by Houston. In September 1843, the Adelsverein met in Germany with Alexander Bourgeois d’Orvanne, a Frenchborn immigrant to the United States who had loaned money to the Republic of Texas during its struggles with Mexico. D’Orvanne, along with his partner Armand Ducos, held a colonization contract for the so-called Bourgeois-Ducos Tract, located to the west of San Antonio. In March 1844, the Adelsverein reincorporated as the Verein zum Schutz deutscher Einwanderer im Texas (Society for the Protection of German Immigrants in Texas) with the goal of promoting, aiding, and protecting German immigrants. The new entity was capitalized with the equivalent of $80,000. Prince Karl Frederich Wilhelm Ludwig of Solms-Braunfels was selected to personally execute the mission in Texas as the commissioner-general. A month later, the Verein purchased the

rights to the Bourgeois-Ducos Tract and initiated a marketing campaign called “Geh mit uns Texas” (Go with Us to Texas). For a fee of about $240, the Verein promised each head-of-household 320 acres, or 160 acres for single men, transportation costs, housing, a first year’s seed for crops, and livestock costs. Infrastructure (such as gins, mills, hospitals, churches, roads, even canals) was to be built. It was a bold and ambitious promise, to say the least, given the conditions in Texas at the time. Their marketing campaign was so successful that they had 10,000 prospective colonists by May 1844. The Bourgeois-Ducos contract, however, had expired in December 1843. It was to be the first of the monumental problems facing the Verein. While d’Orvanne and Solms-Braunfels headed to Texas in May 1844, another individual approached von Castell in Germany with a land opportunity. Known in Germany as Heinrich Franz Fischer, Henry Fisher and his partner, Brukart Mueller (Miller in the states) claimed to have title to a large tract of land. The Fisher-Miller Tract was located north of Enchanted Rock, roughly between the Llano and Colorado rivers and extending to the west, including up to 3,878,000 acres. Fisher said the land was fertile and secure. In June 1844, von Castell entered into partnership with Fisher, paying him $9000 for up-front expenses. On August 1, 1844, Fisher arrived in Texas to serve as a representative of the Verein. By August 1844, it was apparent that d’Orvanne would not be able to extend the deadline that had expired in December 1843. Around the same time, Solms-

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Republic of Texas: John Arrowsmith’s 1844 map of Texas records a number of significant features of the Llano Region at the time of the Republic. It labels Enchanted Rock with today’s name. It also shows the extent of the d’Orvanne and Fisher-Miller colonization contracts, the cities and counties established at the time, the general location of the Comanche, and the rough location of the fabled silver mines.

Braunfels learned of the Fisher-Miller Tract and quickly traveled to meet with Republic officials to discuss the matter. Fisher replaced d’Orvanne as a Verein agent. The Republic officials delivered more disturbing news. Solms-Braunfels learned that Fisher had not actually purchased any land. Fisher had a colonization contract,

the same as d’Orvanne. To date, no one had been settled, no land purchased, and the settlement period was also due to expire imminently, in December 1844. During negotiations to extend the deadline for the Fisher-Miller colonization contract, Solms-Braunfels met Capt. John Coffee “Jack” Hays, the infamous Texas

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Ranger for the Republic. Hays had plenty of information to share with Solms-Braunfels about the Fisher-Miller Tract. Hays and Republic officials described the area as truly beyond the frontier, with regular attacks from roaming bands of Penateka Comanche (called Honey Eaters), Jicarilla Apache, occasional Mescalero Apache, and rogue Lipan Apache, Tonkawa, and other bands. They also related to Solms-Braunfels the poor farming qualities of the area, especially compared with the rich black-dirt lands to the east of the Balcones Escarpment. Only along creeks and rivers was the soil good enough to cultivate. Additionally, the area was 90 miles west of any existing settlements and 300 miles from the inadequate port of Galveston. In November 1844, the first Verein immigrants started arriving from Germany at Galveston. Reports sent back to Germany by Solms-Braunfels throughout 1844 clearly indicate his increasingly negative outlook. The Fisher-Miller Tract was too far from the coast, and the condition of the immigrants arriving on ships from Germany was quite poor. Solms-Braunfels suggested the Verein provide him with the financial resources to acquire land farther east. In parallel efforts, Solms-Braunfels attempted to correct many of the problems with the venture. He was instrumental in establishing Indianola on Matagorda Bay, a new port for German immigration. (Indianola was destroyed by hurricanes in 1875 and 1886.) He established a small private militia to help protect immigrants. Most important, he was able to extend the end date for the Fisher-Miller colonization

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contract to September 1, 1847, and had the conditions required to patent the land eased. After resigning in December 1844, he scouted to the south of Austin for a place to set up a way-station for travelers heading to the Fisher-Miller Tract. This way-station would become New Braunfels. He returned to Germany in the spring of 1845, where he wrote a book about his exploits in Texas. His replacement, Ottfried Hans, Frieherr (Baron) von Meusebach (John O. Meusebach), arrived in Texas in May 1845. As Meusebach watched immigrants collecting at Indianola with no way to get to the Fisher-Miller Tract, he quickly assessed the situation and realized the enormity of the financial, logistical, and cultural problems. One early realization by Meusebach was that New Braunfels was chosen more for aesthetic than practical reasons. It could never support the influx of German immigrants and was still too far from the Fisher-Miller Tract. His first major task was to create a town closer to the FisherMiller tract that could be used as a jumping off point for immigrants. He scouted areas farther to the west of New Braunfels and chose a site on the Pedernales River, to be known as Fredericksburg. On credit, he purchased headrights for 10,000 acres in the location of the future city. Fredericksburg would serve as a critical gateway for immigration. Its rapid growth would help finally to push the frontier beyond Enchanted Rock (“Erchant Reichs” to the Germans) after hundreds of years of attempts by the Spanish, Mexicans, and Texans. Meusebach’s attempts to arrange

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for transportation to the Fisher-Miller Tract quickly became entangled with the war between the United States and Mexico, starting in 1846. Disease and frontier hardships claimed many travelers’ lives as they attempted to push west. Solms-Braunfels intention had always been to establish good relations with the Comanche. Although relations had in general been acceptable between the Germans and Native Americans, tensions were present. Meusebach, known to the Indians as El Sol Colorado, went with a small company to the San Saba River to meet with Buffalo Hump, Santa Anna, Mopechucope, and other Comanche chiefs. A treaty was signed on March 2, 1847, and was ratified two full moons later at Fredericksburg. Most of the Native American groups who were a party to the treaty would for many years make a distinction between German settlers and non-Germans, who were occasionally attacked. One interesting aspect of the treaty was the clause that said the Native Americans could “come to our wigwams and cities without fear,” which led to many an unsettling incident as Native Americans showed up unannounced at the doorstep of German settlers in Fredericksburg and in other settlements. Meusebach was replaced by Hermann Speiss in 1847. That same year, the Verein declared bankruptcy. The Verein was never capitalized enough to fulfill the grand vision of the noblemen. Political conditions and poor business and logistical decisions made the task more challenging. Deception by d’Orvanne and Fisher made for false expectations. Finally, the choice of relatively infertile lands in the Fisher-Miller Tract

made life difficult for the newly arriving German settlers. Although the venture was seen as a failure, it brought 7,380 immigrants to Texas. By 1847, the population of Fredericksburg proper was 966. In the 1850 census, 913 of 1,235 residents of Gillespie County had been born in Europe, mostly from Germany. German culture had a profound influence on the growth of Texas, with the relatively cultured and educated immigrants serving as doctors, lawyers, and in other important capacities. A distinct peace between the German settlers and the Comanche and other now fragmented tribes helped to make the area suitable for settlement. The downtown district of Fredericksburg was placed on the National Register of Historic Places in 1970.

Texas Statehood Texas had annexation offers from both the Mexican and United States governments. On April 12, 1844, Texas and the United States agreed to annexation terms. Two critical issues in the negotiations were the debt held by the Republic and the terms of the transfer of land to the United States upon annexation. In the final agreement, Texas kept its debt, but also retained all of its unsettled land, a unique position among new states joining the Union. This would result in the limited federal lands in Texas today. In April 1845, Mexico recognized Texas as an independent department as a ploy to prevent the Republic from joining the United States. By May, U.S. warships were

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patrolling the Texas coast. On June 4, 1845, the Republic’s president, Anson Jones, signed a peace treaty with the last Comanche tribe engaged in organized hostilities with Texas and announced peace with the Mexican government. On June 16, the Texas Congress formally rejected the offer to join Mexico and accepted the terms of annexation with the United States. Texas entered the United States on December 29, 1845, when the U.S. president, James Polk, signed the annexation agreement. Mexico claimed the Nueces River as the border; the United States claimed the Rio Grande. After the U.S. negotiator was refused a hearing, President Polk sent troops to impose the claimed border. War was declared in May 1846, and the United States soon captured Monterrey, Veracruz, and finally Mexico City. The Treaty of Guadalupe Hidalgo, signed between the United States and Mexico on February 2, 1848, finally brought relative quiet to Texas, at least as far as Mexico was concerned. In addition to securing the present-day Texas border, the treaty also brought New Mexico, California, and Oregon territories under U.S. control.

After Statehood The Central Texas population grew steadily from the late 1840s to the Civil War. The peace treaty signed by Meusebach, along with treaties between the United States and Mexico and the United States and various Native American groups, led to peaceful conditions around the Enchanted Rock area for the first time in almost 100 years. Gillespie County, named for Capt.

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Gillespie of the Texas Rangers, was formed in 1848 with Fredericksburg as the county seat. The city of Llano and Llano County were formed in 1856. The counties of Concho, Kimble, Mason, Blanco, McCulloch, Menard, San Saba, Schleicher, Sutton, and Tom Green to the north and west of Enchanted Rock were established soon thereafter. The progressive, idealistic Germans were very much opposed to slavery. In 1860, before the outbreak of the Civil War, the population of Gillespie County voted 400 to 17 against secession. Surrounding counties (except Mason County) were heavily in favor of secession. Suspicion resulted in tension and even massacres of the pacifist Germans. Gillespie County and Fredericksburg declined during and after the Civil War, while Llano County and Llano grew. Fredericksburg did not regain momentum until well into the twentieth century. In the late 1840s and continuing through the 1870s, Native American populations were pushed into small enclaves. The last skirmish between Native Americans (Comanche) and settlers in Central Texas occurred near Packsaddle Mountain with members of the Moss family in 1873. By 1884, small remnants of the Comanche, Apache, Tonkawa, and other groups were forcibly relocated first to Fort Griffin in North Texas and subsequently to Oklahoma. In 1882, work started on the new Texas State Capitol. Initially, limestone was to be used, but a lack of suitable materials led to a new selection starting in 1895. Texas pink granite (today known as Sunset Red)

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from Granite Mountain near Marble Falls was selected for the building material. It was donated in exchange for an extension of the railroad to the quarry site, which, as the first railroad to penetrate so far into Central Texas, became a key to development and growth. By 1925, ten quarries were operating in the Central Texas Mineral Region. The Cold Spring Granite Company and other companies continue to operate out of Granite Mountain, offering seven different types of granite from around the Central Texas Mineral Region and the world. Loyal Valley granite (called Texas Red) comes from the quarry on the northern boundary of Enchanted Rock SNA. Radiant Red granite comes from the quarry just north of Fredericksburg at Bear Mountain. Between 1886 and 1893, the city of Llano boomed as a result of the injection of capital to extract iron deposits. Like previous mineral extraction efforts in the area, the boom was short-lived, as the quality of the ore was low. Fires at the end of the boom period greatly slowed the growth of the city. Various buildings in Llano were placed on the National Register of Historic Places in the latter half of the twentieth century. In 1911, the Los Almagres Mining Company was formed to try their luck at the Spanish mining site on Honey Creek near San Saba. Little silver was produced. The twentieth century saw continued slow growth, with an emphasis on ranching. Stable water supplies created through the establishment of large reservoirs, starting with Lake Buchanan in 1939, made additional population growth possible.

Central Texas Granite: Many quarries from around the Llano Region produce granite, each with a slightly different character. Texas Red granite is from the quarry just north of Enchanted Rock SNA.

Enchanted Rock Ownership Before the establishment of the Republic of Texas, the area around Enchanted Rock was too unstable for permanent settlement. Comanche controlled the area, and remnants of other Native American nations frequently made raids. Settlement in many areas would have meant eventual death. Enchanted Rock itself was included in a land grant soon after the Republic of Texas established its aggressive immigration policies in 1836. Anavato and María Martínez were awarded a headright certificate for a block of land that included Enchanted Rock SNA in 1838 in recognition of Anavato’s aid to the Republic of Texas government in the fight against Mexico. The Martínez family, however, never patented the land. In 1841, the Martínez family sold their

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Martínez Land Grant: Land including Enchanted Rock was granted to Anavato Martínez in March 1838, as documented in this Gillespie County record.

land-grant rights to James Robinson. In 1844, Robinson sold the rights to his business partner, Samuel A. Maverick. As Maverick did not follow the practice of the day by branding his cattle, his name eventually was applied to anyone who refused to follow conventions. Maverick searched the area for minerals and had the property surveyed in 1847. He finally patented the land, including Enchanted Rock, on September 22, 1851. The Mavericks held the property in the family until 1880, when Samuel’s widow, Mary, sold it to N. P. P. Browne. Maverick’s widow retained the mineral rights, just in case. Browne sold the property to John Moss in 1886. The Moss family has held extensive land holdings in the Enchanted Rock area since the 1830s. Mathew Moss, John’s father, was awarded a land grant in the future Llano County area, including Dutch Mountain, for his participation in the Battle of San Jacinto as part of Sherman’s Regiment and for his part in helping to settle Stephen F. Austin’s colony. Mathew resided

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in Travis County on his wife’s land grant until 1857, when the couple moved onto a new land grant in newly established Llano County. Mathew Moss, like Maverick, thought there was silver in the area, near Bullhead Mountain, which can be seen from the top of Enchanted Rock Dome. John sold the land to Damon “J.D.” Slator later in 1886. The first born of Mathew’s children, Julie, was married to Slator, connecting the families together. Charles “C.T.” and Aaron “A.F.” Moss, who were also Mathew’s sons, bought the Enchanted Rock land back from Slator in 1895. It was Charles and Aaron who were involved in the last skirmish between Comanche and settlers near Packsaddle Mountain. They added it to the 30,000 acres of land they jointly purchased from Mary Maverick, Samuel’s widow, in 1882. In 1897, the Moss brothers split their jointly held share of 30,000 acres equally. They held 1,200 acres, including Enchanted Rock, in common. C.T. eventually acquired his brother’s share. C.T.’s son, Tate Moss, inherited the property in 1927. Tate held the property until 1946, when he sold it to Albert Faltin. Faltin later sold a half-interest to Charles H. Moss, C.T.’s grandson. Charles acquired full title in 1947. Charles and his wife held the land until 1978, when it was purchased by the Nature Conservancy. The Nature Conservancy quickly sold the property to the State of Texas.

Tourists at Enchanted Rock German-born Karl Friedrich Hermann Lungkwitz, who migrated from Germany

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to Fredericksburg, was an early tourist to Enchanted Rock. One of the first major landscape painters in Texas, he painted romantic images of Enchanted Rock numerous times in the 1870s. In 1888, he wrote the following about Enchanted Rock: I wanted to penetrate more into the interior of the granite mountains. I found and painted a few charming views of the Enchanted Rock and the neighboring mountain ridges from my position on a very precipitous peak called Rauhenkopf. To reach my point of observation, I had to hike one and one half miles every day through

mesquite brush and into rocky ground without any path. . . . Within a radius of six miles, one cannot find any human habitation—one can only camp out. The area at Crabapple near Grebe’s and Max’s farm is wildly romantic with many beautiful views. Enchanted Rock has been open to public visitation since the end of the 1800s. The area was opened as a private park by the Moss family on June 22, 1927. Thousands of people attended the festivities, including the Texas governor at the time, Dan Moody, who referred to Enchanted Rock as “Texas’ most wonderful summer resort.”

Hermann Lungkwitz Painting, 1856: Hermann Lungkwitz, one of Texas’ earliest important landscape painters, lived near Fredericksburg for many years. One of his favorite subjects was Enchanted Rock, which he traveled to regularly from his home. This romanticized oil painting of Enchanted Rock was created in 1856.

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A new Pontiac was driven to the top on the occasion. In the late 1920s church services were regularly held the last Sunday of the month at the summit of Enchanted Rock. The park continued to operate as a private enterprise until its transfer to the state. In 1971, while the Moss family still owned Enchanted Rock, the area was designated a National Natural Landmark. The designation is a mechanism used to recognize publicly and privately owned land for its unique biological and geological features. By 1977, it is estimated that 50,000 tourists visited the area annually. In 1978, the Moss family desired to sell the property. They had offers from a wide variety of potential buyers with grand plans. These included building townhouses among the granite domes, establishment of a granite quarry, or even creation of a Mount Rushmore–like monument to Texas heroes. The Moss family preferred to have the land preserved, but the Texas Parks and Wildlife Department lacked the funds. On March 1, 1978, the Nature Conservancy (TNC) purchased the land for $1.3 million, with the understanding that the state would reimburse TNC for the land. TNC deeded the land to the State of Texas a few days later, on March 7, with compensation deferred until the state could raise the funds. The State of Texas later compensated TNC for its financial outlay. Additional funding was eventually secured to support renovations, including relocation of the campground across Sandy Creek. Enchanted Rock State Natural Area was opened to the public in March 1984.

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Visitation to the park peaked at 360,000 visits in the late 1990s. This comes out to roughly 1,000 people per day. Since there is little visitation on weekdays and in the winter, the park was crawling with people on spring weekend days, with parked cars lining the highway outside the park. The large numbers of visitors caused extensive damage, including social trails, erosion, damage to plants, and other disturbing developments. In response to the ever-increasing levels of visitation to the park, capacity limits were established in 1999, restricting the number of people who are allowed to visit the park on a given day. Once the park reaches this level, it is closed until 5 pm, when many of the day trippers depart. Following the changes in park policy, visitation at Enchanted Rock dropped to below 300,000 unique visits per year. Organizations like the Central Texas Climbing Committee (CTCC) and the Friends of Enchanted Rock (FoER) work with the park superintendent to help with trail and climbing maintenance. The FoER has regular trail maintenance days, which the public may support. The CTCC is responsible, in conjunction with the park staff, for maintaining the climbing routes in the park.

Enchanted Rock Legends and Stories Numerous legends and stories surround Enchanted Rock. Some stories are true and some are not. Time has weakened our ability to distinguish between the two. An 1838 article in the New York Mirror documenting a trip to the San Saba mine describes an “Enchanted” or “Holy”

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mountain in the area. The official western naming of Enchanted Rock probably originated somewhere around the time this article was published. The 1844 map by Arrowsmith shows “Enchanted Rock” as the name.

Mineral Riches The stories of great mineral wealth and lost mines are a combination of misunderstanding of the mineralogy of the area by the Spanish and of subsequent marketing campaigns by Stephen Austin, the Verein, and others, who built on the earlier Spanish accounts and stories. Many of the Spanish stories originated from the Native Americans they encountered in their early exploration of the area. Creative mapmakers helped propagate the myths. Native Americans occasionally traded silver of an unknown origin with the Spanish and later the Texans. During the Galvan expedition in 1753, tales were told by the Apache of a Hill of Red Ochre, or Cerro del Almagre, near Honey Creek, located near today’s Riley Mountains to the northeast of Enchanted Rock SNA. The red rocks were thought to contain valuable ore suitable for mining. The Miranda expedition in 1756, during which Enchanted Rock was noted in the logs, was formed as a follow-up to the Galvan expedition. Soon after, attacks on the San Sabá Mission made travel to the area quite hazardous. Around 1778 the French sent an expedition that also reported favorable impressions of mining possibilities. Revolution in France and constant attacks by Comanche,

Apache, and others made the area unsafe for any mining activities. In 1829, Stephen F. Austin, hearing of fabled mines near San Saba, sent an expedition into what he believed was the Los Almagres mine. Although there was no evidence of any mineral wealth, Austin included in his 1830 marketing materials a map labeling a “silver mine” near the previous location of the San Saba mission and presidio, and the legend was here to stay. A rancher’s discovery of a mine in the 1970s, and subsequent geological and archaeological investigation, indicated that the mine was probably Los Almagres, at the base of Packsaddle Mountain near Honey Creek, in Llano County. James Bowie of Alamo fame made numerous attempts to learn the location of the silver mine from the Native Americans. Stories of abandoned or buried silver, gold, or other mineral wealth began to crop up. One story talked of silver left behind during the hasty evacuation of the San Sabá Mission in 1758. Supposedly a large quantity of silver was left in a cave or buried nearby. Other stories talk of the silver being submerged in a man-made lake. Yet another story talks of a silver bell being cast and buried in the ground to hide it. In 1838, a band of Comanche led by Chief Buffalo Hump killed James Webster and the male members of his wagon team traveling near Enchanted Rock. His wife and their two children were captured and taken to Enchanted Rock. Released in 1840, they talked of gold and silver mines and fantastic brilliant stones in possession of the Comanche. The stones were most likely quartz.

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In 1841, in the book Texas, William Kennedy noted Enchanted Rock as the gateway to silver mines, along with its importance to the Native Americans. His description of the area reads: About twenty-five miles from the Colorado, on the northwestern branch of the Piedernales [Pedernales], is a rock, considered one of the natural curiosities of Texas. It is about two hundred feet high, of an oval form, and half embedded in the soil. It is composed of particolored flints, and reflects the sunbeams with great brilliancy. A spring gushing forth near its summit sprinkles its sides with water. Owing, it is supposed, to the presence of some phosphoric substance, it wears an illuminated aspect on dark nights. This rock is held sacred by the Indians, who visit it at stated periods, for the purpose of paying homage to the Great Spirit, after their wild and primitive fashion. Other accounts from the mid-1800s describe the rock as being made of platinum. During much of the late 1800s, numerous creative claimants reported lost mines or lost treasure and sought funding to remove it. All of their claims were, of course, untrue. The first decade of the twentieth century saw a renewed interest in the mine as translations of Miranda’s expedition became available. The Los Almagres Mining Company was formed to once again attempt to work the mine. It was never commercially viable.

Some gold has in fact been mined from the general area, reaching its peak in the 1880s. There was a gold-dust mine on Sandy Creek at one time, owned by Gail Borden of Borden Milk fame. Iron was also produced in the area. There have been successful if low-yield silver mines operating in Llano County continuously. From the 1930s it was thought that the area contained uranium deposits. Initial tests showed radioactivity from the rocks, but then, all rocks are radioactive to some degree. The 1950s brought near-frenzied searches for deposits. By 1954, although radioactivity was present, it was determined that the concentrations were not commercially viable. The Hickory Sandstone formation, found within the Llano Region, contains enough iron to make it nearly rich enough to mine. Small pockets within the Valley Spring gneiss domain contain iron deposits that have been mined. Blue topaz is found in Mason County. Other minerals that have been mined, whether with commercial success or not, are graphite, soapstone, manganese, tin, bismuth, tungsten, magnetite, vermiculite, talc, serpentine, feldspar, lead, yttrium, zinc, copper, and molybdenum. Granite, for use in kitchens and as a building stone, continues to be mined throughout the Llano Region.

Native American Stories The Tonkawa, Comanche, and Apache all apparently believed Enchanted Rock to be a sacred place. Whether any of the tribes feared the place is another matter. Given

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the proliferation of Native American sites along Sandy Creek and on the granite domes, it is highly unlikely that ancient tribes were frightened of the place. Samuel J. Reid’s 1848 book, The Scouting Expeditions of McCulloch’s Texas Rangers, conveyed a story he had gathered from Native Americans. It went: Indians had a great awe, amounting almost to reverence for it, and would tell many legendary tales connected with it and the fate of a few brave warriors, the last of a tribe now extinct, who defended themselves there for many years as in a strong castle, against the attacks of their hostile brethren, but they were finally overcome and totally annihilated, and ever since, the “Enchanted Rock” has been looked upon as the exclusive property of these phantom warriors. This is one of the tales which the Indian tell concerning it. The rock forms an apex of a high, round hill very rugged and difficult of ascent. In the center there is a hollow, in the shape of a bowl, and sufficiently large to allow a small party of men to lie in it, thus forming a small fort, the projecting and elevated sides serving as protection. A conquistador captured by the Tonkawa described how he escaped from them by losing himself among the rocks at Enchanted Rock. When he finally reemerged, he explained to the Tonkawa that he was swallowed by the rock and joined the spirits enchanting the place. This gave rise to the “pale man swallowed by a rock and reborn as one of their own” legend.

Stories about sacrifices at Enchanted Rock are probably not true. The Native American tribes occupying the area did not engage in human sacrifices, at least not on a regular basis; however, the Comanche and Tonkawa did practice scalping. The Tonkawa may have engaged in cannibalism. The Native Americans did capture and kill settlers and travelers to the Enchanted Rock Area. Also, women and children were frequently kept by the Native Americans. At least two stories include sacrifices. One involves a Comanche attack on the San José Mission where an Indian chief ’s daughter was freed and taken to Enchanted Rock to be sacrificed. The second story talks of an Indian chief who sacrificed his daughter on Enchanted Rock to please the gods, but the act angered the gods instead, and the spirit of the chief was forced to walk on the rock forever. His footprints can be seen at the top of the smooth-domed rock. Other stories talk of a ghostly glow enveloping those who trek to the top, followed by a spinning of Enchanted Rock accompanied by incredible, peculiar sounds. The Tonkawa believed that ghost fires flickered at the top. They reported weird creaking and groaning among the rocks. Mysterious flames were said to dance on the summit on moonlit nights. According to one account: “At night spirit fires dance on the summit and by day millions of isinglass stars glint in the sunlight.” Another tale tells of a Native American princess who threw herself off the rocks when she saw her tribe slaughtered by other Native American tribes. Her spirit is said to continue haunting the area. There is a tale of a Caucasian woman

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captured by Indians. She escaped and still lives on the rock, where her screams are sometimes heard. There certainly were kidnappings of Caucasian women by Native Americans in the middle 1800s. Visit the park yourself to see if there is any screaming coming from anything other than the present-day visitors.

Stand-Off The most famous story involving Native Americans and Enchanted Rock has to do with Texas Ranger Capt. Jack “Coffee” Hays holding off a band of Comanche while surveying the area. Conveyed in Samuel J. Reid’s 1848 book and based on his interview of Hays, the story goes as follows: In 1841, Hays had been exploring with his party of fifteen to twenty others beyond the western frontier settlements. Hays went ahead to do some scouting and encountered a large force of Comanche. They pursued him on horseback to near Enchanted Rock, where his horse began to tire. Unknown to the Comanche, Hays was heavily armed with his rifle and one of the new five-shooters. From that point: Hays, cut-off, closely pressed, made good his retreat to the top of the hill. Reaching the Enchanted Rock, he there entrenched himself and determined to sell his life dearly for he had scarcely a gleam of hope to escape. Indians arriving at the summit set up a most hideous howl, being bent on taking this Devil Jack. As they approached Hays would rise and level his rifle, knowing him they dropped back. He kept them at

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bay for an hour howling around him all the while. Finally emboldened, they approached so that it became necessary for him to work in earnest. He discharged his rifle, using his five shooter he felled them on all sides, this keeping them off until he could reload. He defended himself for three long hours, when the Indians became furiously exasperated and rushed in mass and gained the top on one side of the hill. His men heard the rifle and had been fighting most desperately to reach their leader, now succeeded in breaking through the file of Indians on the other side, and arrived just in time to save him. He considers it one of the tightest little places that he was ever in. The Indians, who had believed for a long time that he lived a charmed life, were then more than ever convinced of the fact. A plaque commemorating the event was placed at the top of Enchanted Rock in 1936 by the State of Texas. It currently hangs in the gazebo at the beginning of the Summit Trail.

Strange Sounds There are numerous stories about the domes creaking or groaning. Some relate the creaking to the footsteps of the ghosts of Indian tribal leaders, forced to remain on Enchanted Rock for their ill deeds. Although the rock in modern times has never been heard to groan or creak, it does make odd noises. When you walk on the domes, your footsteps can sometimes make a hollow sound where the rock sheet

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is thin and there is a gap underneath the place where you are standing. Also, small pieces of granite may break off as you walk on the granite surface, creating a cracking crunchy sound that is somewhat unusual. Small granite pebbles occasionally roll down the flanks of the granite domes, producing an unusual tinkling sound. Maybe these sounds are the source of some of the effects described in legends.

Second Largest Exfoliation Dome Another interesting legend that survives to this day is that Enchanted Rock is the second largest exfoliation dome in the United States, after Stone Mountain in Georgia. That would be true if the bulk of the Sierra

Nevada Mountains in California, including Half-Dome and other exfoliation features, were excluded. Other large batholith features also exist in Idaho. It is possible that it is the second largest in the eastern United States. Central Texas, including Enchanted Rock, has been inhabited by people for at least the past 13,000 years. From Paleo-Indian peoples hunting post–Ice Age animals to various Prehistoric Native Americans, such as the Tonkawa, Apache, and Comanche to the Spanish, Mexicans, French, Germans, Anglo-Americans, and others, the area has inspired awe, myth, lust for wealth, and a desire to first conquer and control and now to preserve the land.

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Freshman Mountain Exfoliation Dome: Classic features of an exfoliation dome can be seen on Freshman Mountain, viewed from the flank of Enchanted Rock Dome. The top of Freshman Mountain is covered with plateau live oak trees.

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Geology

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Visitors to Enchanted Rock SNA most certainly will notice the startling strangeness of the landforms. Bald, rounded domes made of pinkish red rock stand in stark contrast to the tree-covered, more rugged terrain on white or gray rock found throughout much of the Texas Hill Country. What complex series of events led to the creation of the distinctive round granite domes at the park? Why is the Llano Region a mecca for geologists worldwide? Enchanted Rock SNA and other nearby locales within the Llano Region offer interesting glimpses into landforms shaped by forces on Earth’s continents more than 1 billion years ago. A broad view is necessary to understand the complex geological origins of the domes. To gather this view, let’s examine the various geologic influences, traveling for the most part back in time. Before proceeding, please refer to the chart to familiarize yourself with the geologic time scale used by geologists.

Edwards Plateau, Texas Hill Country, and Balcones Fault Zone Enchanted Rock SNA sits at the western

edge of a much larger area known as the Texas Hill Country (a.k.a. Balcones Canyonlands), a landscape with numerous streams, steep canyons, caves, springs, fairly dense vegetation with medium to large trees, and underground aquifers. Visitors to Central Texas are often pleasantly surprised by the rugged terrain and wildflowers, which are contrary to their expectations of flat plains like those found in East and North Texas. The Texas Hill Country developed from an even larger, relatively flat region known as the Edwards Plateau. The Edwards Plateau is bounded roughly by the Pecos River to the west and the Balcones Escarpment to the south and east (an escarpment is an abrupt change in the elevation of land). The flat topography was due to a blanket of sea floor deposits from much earlier sea inundations. When the sea floor was uplifted, the water retreated and the dry land became the Edwards Plateau. Today, numerous rivers, such as the Lower Colorado, Llano, Pedernales, Guadalupe, San Marcos, and others, cut canyons into the plateau, forming the Texas Hill Country. It is not that the hills went up but rather that the valleys went down. The hills are remnants,

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Geologic Time Chart: Geologists divide Earth history into eons, eras, periods, and epochs. These are nested intervals of time—several epochs compose a period, which together with other geologic periods make an era. The Paleozoic, Mesozoic, and Cenozoic eras make up the Phanerozoic Eon. Boundaries between time units are based on abrupt changes in the fossil record (including mass extinctions), which in turn are related to climatic or other factors that could have triggered change on a worldwide scale. For example, the mass extinction event in which dinosaurs disappeared from the fossil record 65 million years ago defines the end of the Mesozoic Era.

temporary features being removed by erosion. Geologists sometimes jest that the area should be referred to as the Texas Valley Country. Starting at around 60 mya, during the Paleocene Epoch of the Tertiary Period, the shoreline of the Gulf of Mexico was not far distant from where Austin is today. The Rocky Mountains, created by recent uplift, were partially drained to the southeast through Central Texas from newly formed streams. Precursors to the Lower Colorado River and its modern-day tributaries brought enormously thick and heavy

deposits of sand and mud to the Gulf, over time extending the coastline forward in the direction of the Gulf. Land that is now part of Texas grew at the expense of the Gulf of Mexico. By the Oligocene Epoch, the coastline of Texas had been displaced as far as 125 miles, near the present coastline. The deposited material was very heavy and was underlaid by thick salt beds deposited earlier, during the Jurassic Period. The entire mass slid toward the Gulf, opening up fault zones paralleling the coastline. Each fault zone consists of a series of normal faults that trend north-northeast.

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Llano Region Bluebonnets: In a good year with a wet early winter, bluebonnets carpet the ground in early April, drawing visitors to the Llano Region.

Normal faults are produced by stretching, or tension. (Compression produces reverse faults, in which blocks are pushed up against the force of gravity). During an earthquake, fractures along a normal fault allow the block on one side of the fault to drop down relative to an adjacent block on the other side. Over time, thousands of small movements along a fault can permit the land on one side of a fault to subside very substantially. As the coastline migrated to the southeast, so did the zone of active faults.

At roughly 17 mya (during the Miocene Epoch), the Balcones Fault Zone became active. Over the few million years of activity along the Balcones Fault Zone, the Gulf Coastal Plain was lowered 600 to 1,000 feet relative to the Edwards Plateau. The result was the Balcones Escarpment. For the most part, the Balcones and other fault zones of the Gulf Coast are inactive today.1 Central Texas is one of the least seismically active areas within the United States. Earthquakes recorded within the past century have been few and of trivial

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magnitude, an example being the April 2008 magnitude 3.9 earthquake centered just southeast of San Antonio. Seismic activity along the Balcones Fault Zone did not directly affect the Enchanted Rock SNA, but formation of the Balcones Escarpment had important consequences both along the escarpment and to the west. The abruptly higher elevation of the Edwards Plateau encouraged streams to eat into its eastern parts, leading to accelerated erosion and development of the Texas Hill Country.

Erosion of the rather pure limestone, overlaid by siltstone and poorly cemented sandstone deposited during the Cretaceous Period, was accelerated as a result of the uplift. Deeper, older strata, consisting of limestone that was more resistant to erosion, were exposed and eroded much more slowly. As a result, the rock exposed at the surface in the Edwards Plateau remains higher in elevation and is much older than the rock exposed to the east of the escarpment. Still farther west the Llano River, Sandy Creek, and other streams have

Mesozoic and Cenozoic Features: During the Mesozoic Era, after the breakup of Pangaea, a broad swath of land known as the Jurassic-Triassic Uplift was raised, keeping the Sundance Sea (not shown) out of the Llano Region. In the mid-Cretaceous Period, the Balcones Igneous Province developed in conjunction with the Laramide Orogeny, which formed the Rocky Mountains. The Trans-Pecos Igneous Province was active from the Miocene to the Eocene epochs, encompassing volcanic activity in the Big Bend, Davis Mountains, and other West Texas locations. In the Miocene Epoch, deposits on top of unstable Jurassic Period salt beds led to the development of fault zones, including the Balcones Fault Zone and others parallel to the Texas coastline, creating the Balcones Escarpment and Edwards Plateau. Erosion within the Llano Region brought granite-derived sands to the Gulf Coast, creating the Texas Hill Country.

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Deposit Timeline: The Llano Region experienced numerous inundation events over the last 550 million years. Each inundation led to deposits in shallow coastline or open sea conditions. The duration of inundation (indicated here by blue) does not necessarily correlate to the depth of a deposit. There are no records of inundations during the Great Unconformity, which occurred more than 550 mya.

carved a basin out of the sedimentary rock, exposing deeper, older rocks. Today, the western Edwards Plateau is roughly 300 feet higher than the land to the east of the Balcones Escarpment, near Austin, and as much as 1,000 feet higher near Del Rio. The escarpment is an important physical demarcation and barrier to the migration of plants and animals that live on either side, and it triggers important effects on Central Texas weather.

Incursion of Shallow Seas Periods of Inundation Sea level fluctuates over time, depending on the amount of water held in ice sheets at the poles and other locations. Land may also rise or subside relative to sea level.

Before the period of seismic activity along the coastal fault zones, going back more than 500 million years, shallow seas periodically covered broad areas of Texas and elsewhere in the United States. Central Texas has experienced numerous marine inundations. The most recent occurred during the Cretaceous Period, between 110 mya and 93 mya, when the Cretaceous Seaway (also called the Western Interior Sea) extended up to the Arctic Ocean, separating the present-day eastern and western United States by a wide body of water. Much of the flat topography of the Great Plains is underlaid by deposits from this inundation. The Llano Region, including Enchanted Rock SNA, was either covered only shallowly or possibly not at all, with small islands sticking up out of the water. During the Triassic and Jurassic periods, subsidence lowered much of West Texas,

Cretaceous Seaway: The Cretaceous Seaway (blue) inundated much of North America during the Cretaceous Period. The Great Plains consist primarily of deposits from this inundation. Note that the diagram shows the greatest extent of the sea, but the sea may not have covered all of the area simultaneously.

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which as a result lay beneath another body of water known as the Sundance Sea. Central Texas at that time was above sea level and experiencing erosion. Therefore, Triassic and Jurassic deposits are present in West Texas and beneath the Gulf of Mexico, but absent from most of Central Texas. Two other important inundation intervals occurred more distantly in the past. The earlier one spanned the Cambrian and Ordovician periods, at roughly 500 mya, and the more recent encompassed the Pennsylvanian Period, centered at approximately 300 mya. Other minor inundations laid deposits during the Silurian and Devonian periods. Inundation could be terminated in several ways: (1) The sea could become completely filled with sediment, (2) a worldwide fall of sea level could expose the land, or (3) the land could be uplifted relative to the sea level. The Cretaceous Seaway and Sundance Sea both ceased to exist through a combination of these processes.

Nature of Deposits Sediment can be deposited rapidly or slowly, and thus the duration of an inundation does not necessarily correspond to the thickness of the deposits. During each sea incursion, deposits with varying characteristics were laid down. They were sand and mud if streams were nearby. Streams eroding into limestone transported calcium carbonate in solution, which then precipitated to the bottom of a shallow sea. Salt carried in solution made the oceans salty. Undersea channels may have carried the streams’ load away from the coastline.

In localities more distant from streams, the prevailing marine organisms, including algae, oysters, and other mollusks also deposited calcium carbonate, forming beds of ooze on the sea floor. Reefs grew up in some of these areas, although in the earlier days the reefs were secreted by other organisms, not by the corals that build the supporting framework of modern reefs. From time to time, the nature of deposits at a given location changed with variations in water depth and other factors (such as proximity to land) that governed the type of sediment being delivered. The result would be a stacking of different deposits, commonly with mixing during the slow transition from one type of deposit to another. Such a vertical succession invites geologists to interpret what had changed, and why.

From Sediment to Rock As deposits accumulated, deeper material was compressed and compacted by the weight of the overlying material and lithified, or transformed into rock. These complex physical, chemical, or biological changes, known as diagenesis, transform sand, silt, and mud into sandstone, siltstone, and mudstone. Calcium carbonate ooze is transformed into limestone. A mixture of materials, such as sand and calcium carbonate together, leads to sedimentary rock with characteristics of the materials present. Geologists define a formation to refer to a stratum (for example, a stratum of sandstone) or set of associated strata (for example, intermixed beds of sandstone and mudstone) that have a distinctive

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appearance and are thick enough to represent on a geologic map. Formations are commonly named after a locality; for example, Hickory sandstone, present in the Llano Region, is named after Hickory Creek. Multiple formations may be placed in a group where there is some relationship between them, and the groups may be organized into supergroups. Formations are sometimes divided into subunits known as members. Other organizational units are also possible. Not all formations that are present in a region (the Llano Region) are present in a given location (Hickory Creek), because rocks are not made continuously, either in space or in time. Deposition of sediment prevails below sea level, and when an area is above sea level, streams erode the land away. Deposition constructs a rock record, and erosion destroys it. Earth is dynamic, consuming itself in one place to feed itself somewhere else. Formations, once deposited, become partially eroded, and in the long run none of them survives.

Llano Region Rock Periods of deposition and subsequent diagenesis produced numerous formations across the Edwards Plateau and Llano Region. Glen Rose limestone and Hensel sandstone, among many other units, originated during the Cretaceous Period inundation. Smithwick shale and Marble Falls limestone were created in the Pennsylvanian Period. Minor, scattered rocks represent the Silurian and Devonian. The Ordovician Period produced the thick and erosion-resistant members of the

Ellenburger Group (Tanyard, Gorman, and Honeycut formations), deposited over much of Texas, extending to the northeast in sea conditions similar to those found in the present-day Bahamas. A transition occurred somewhere around the OrdovicianCambrian boundary, when the Wilberns Formation (San Saba dolomite, Point Peak siltstone, Morgan Creek limestone, and Welge sandstone) was deposited in a shallow to deeper sea environment near the coastline to the northwest. The Riley Formation (Lion Mountain sandstone, Cap Mountain limestone, and Hickory sandstone) was deposited in the Cambrian Period in a shallow sea environment not far from the shoreline. Lion Mountain sandstone is interesting in that it appears to be formed partly from trilobite excrement.

Unconformities and the Stratigraphic Column A stratigraphic column is employed to help visualize the order and relative thickness of formations. It shows formations in sequence (with younger strata typically lying on older strata), as though all of them were present in one location. Assembling a stratigraphic column is like completing a jigsaw puzzle, placing scattered components into their correct relationships. Also described within a stratigraphic column are buried surfaces of erosion called unconformities. The duration of the erosion may have been long or short in geologic time. Unconformities signify that a later part of the rock record has been lost through erosion, with deposition of additional sediment on the eroded surface.

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Ironically, even though part of the rock record is lost, unconformities provide critical clues about the sequence of events at a given location, especially when comparing one locale to another. A disconformity appears when sedimentary strata, deposited typically below sea level, are uplifted and eroded, and then the sea returns to deposit more strata. Strata above and below the erosion surface are parallel. When the lower (older) strata are tilted before the upper (younger) strata are deposited, an angular unconformity forms, and the strata above and below the unconformity are not parallel. In a nonconformity, sedimentary strata lie on metamorphic or intrusive igneous rocks that originated very deep within the earth. A nonconformity signifies extensive erosion occurring over perhaps hundreds of millions of years. The Llano Region contains magnificent examples of all three varieties of unconformity.

Plate Tectonics

Stratigraphic Column, Eastern Llano Region: This stratigraphic column identifies important rock formations in the order they are found in within the eastern Llano Region. Rocks that are higher (and usually younger) are at the top; older rocks are lower in the column. The layers are shown in their relative thickness, and unconformities are indicated by a line. In no single location within the Llano Region do all of the strata shown in the stratigraphic column occur.

The outer solid shell of Earth is known as the lithosphere. It consists of the oceanic or continental crust and an outermost, solid part of the mantle.2 The lithosphere is broken into a dozen or so plates that are in motion, riding on an underlying, slightly melted zone in the mantle known as the asthenosphere. A tectonic plate can be capped with oceanic crust, continental crust, or both. Oceanic crust is relatively thin and dense, consisting primarily of basalt and gabbro. Continental crust is thicker, less dense, and is composed largely of granite and other igneous rocks (known

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Plate Tectonics and Subduction: The top diagram shows the destruction of oceanic lithosphere by subduction and the resulting deformation, metamorphism, orogeny, and batholith creation. The bottom diagram shows continental plates fused together.

as basement rock) deep underground overlaid by sedimentary rock. Continental crust often extends beyond today’s shoreline as a continental shelf, and it can be exposed during geological periods when sea levels are low. Plates can collide, pull apart, or slide past one another. The interactions at plate boundaries are known as tectonics. It is

along a boundary between adjacent plates where the geologic action occurs. When plates collide with oceanic crust on the margin of at least one of the plates, the plate containing higher-density material is bent downward, or subducted, beneath the other plate, descending deep into the earth’s mantle. The descending plate drags water along with it, which at depth

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encourages some of the plate and overlying mantle to melt. The melted material, magma, rises because it is of low density. Higher-density plate material is recycled in the asthenosphere. Over hundreds of millions of years, entire ocean basins are recycled through this process. Magma can pool underground or find its way to the earth’s surface, creating a volcanic field. Extruded material in the form of ash and lava builds mountains over the volcanic field. A volcanic field in the open ocean, the result of collision between two plates with oceanic crust on their margins, forms a volcanic island arc. One example is the Aleutian Islands, where the Pacific plate is undergoing subduction beneath the North American plate. A volcanic field along a coastline, from subduction of a plate with oceanic crust on its margin between the adjacent plate containing continental crust on its margin, is known as a continental margin volcanic arc. An example is the Cascade Mountain Range, including Mount St. Helens, Mount Rainier, and Mount Shasta, which runs through northern California extending up to Washington State. The collision of plates with continental crust on the margin of both plates produces a massive pile-up of low-density material, leading to great crumpling, deformation, and thickening of the crust. One plate can ride up and over the opposing crust, forming a massive mountain range. Much like an iceberg, the bulk of the mountain range is hidden. A mountain range such as the Himalayas, which rises 8.8 kilometers above sea level, may extend 30–70 kilometers or more below sea level in what is

known as the mountain root zone. Deep within the crust, where pressures and temperatures are high, melting takes place, forming magma. A mountain-building event is known as orogeny. An orogen is the remnant physical manifestation of orogeny. An orogen may be mountains or remnants left behind after erosion has worn the mountains away. Through plate tectonics, rock with vastly different origins may be sutured together, creating individual terranes. The study of terranes provides valuable clues to the history of continental crust. Plates may also diverge, resulting in rift valleys and mid-ocean ridges. Rift valleys develop where the continental crust separates. Rifting may also occur as a result of continental collision, where the crust cracks as a result of the collision. Rifting with associated subsidence can lead to eventual inundation by the ocean, as is occurring in the present-day Red Sea and south into the Great Lakes region of northeast Africa. Mid-oceanic ridges develop along divergent plate boundaries, where opposing convection currents in the lower mantle cause rock in the upper mantle to melt into very hot basaltic magma. The magma rises up, pushes the plates apart, and deposits basalt in the void. (Basaltic magma may also make its way to the surface above anomalous hot spots in the mantle, which cause the upper mantle to expand and melt. One such hot spot lies below the Hawaiian Islands.) One other possibility is for plates to slide past one another, as is occurring along the San Andreas Fault in California.

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Pangaea and the Ouachita Mountains Central Texas has been the site of mountain building at least twice in the last 1,300 million years.3 Looking today at the hilly terrain of Central Texas, it is hard for us to imagine mountain ranges there similar to today’s Himalayas. Starting roughly 360 mya, during the Mississippian Period, in an interval of time sometimes referred to as the Paleozoic mountain-building era, an amalgamation of landmasses that may not have resembled today’s continents in size, shape, or geographical location began to fuse together. The resulting supercontinent, known as Pangaea (Greek, for “all lands”), was a quiltlike patchwork of landmasses with

Pangaea: Continents came together to form the supercontinent Pangaea starting roughly 360 mya and lasting into the Triassic Period. The Ouachita Mountain Range was created through Central Texas as a result of the collision of the South American part of Gondwana and Laurentia (the future North America).

mountain belts resembling raised stitches at the joints. Today’s southern hemisphere, including the African and South American continents plus India, made up a land unit known as Gondwana. The collision of the African continental crust making up Gondwana with the (present-day) eastern continental margin of Laurentia (the proto–North American continent) about 340 mya created the Appalachians and the corresponding Atlas Mountains in Africa. As the fusion continued, interaction between the South American part of Gondwana and Laurentia led to the Ouachita Orogeny roughly at 310 mya. A tall, S-shaped mountain range extended from Arkansas into Oklahoma, turning south through Dallas–Fort Worth and Austin, then bending to the west toward Marathon, Texas. Remnants are visible in southern Oklahoma into Arkansas. Another remnant of the Ouachita Range is found in rock exposures near Marathon, Texas. Vast volumes of Paleozoic Era sediment from erosion of the Ouachita Mountains can be found in northern Texas and Oklahoma. In Central Texas, remnants of the Ouachita Mountains were subsequently buried by sediment during the Cretaceous inundations. Drilling deep beneath Austin reveals evidence of the Ouachita Orogen. Pangaea began to break up in the late Paleozoic Era at approximately 220 mya, and the rifted fragments, the modern continents, drifted in various directions. Eventually the Yucatan, now part of Mexico, broke away from Texas, opening up the Gulf of Mexico.

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Paleozoic Features: Collision between South America and Laurentia led to the building of the Ouachita Mountain Range. The Llano Fault Zone developed in a high plateau adjacent to the mountains. Further away, the land subsided and became inundated.

Llano Region Deep in the heart of Texas, the Llano Region covers an oval-shaped area approximately 95 miles by 60 miles, centered roughly on Llano, Texas. The region has other aliases: Llano Uplift, Llano Basin, and Central Texas Mineral Region. Now, you may ask how a place can be both an uplift and a basin. The origins of the Llano Uplift are complex, involving many events over hundreds of millions of years. The Llano Uplift is a region where the earth has been gently arched. Where strata that are exposed

around the margin continue away from the Llano Uplift, they descend out of sight beneath younger strata. After uplift and erosion, rocks that are stratigraphically lower (older) may be topographically higher than the equivalent rock in the surrounding area. The relationships seen today are the inverse of the way they began. Let’s review the geologic history. Most recent was the regional (and relative) uplift of the Edwards Plateau. Before that, in the Jurassic and Triassic periods in the early Mesozoic Era, another regional uplift occurred, leaving Central Texas high and dry as the Sundance Sea and developing Gulf of

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Horst and Graben Terrain: (Top) Fault action is the first step in creating a horst and graben landscape, where blocks of land drop relative to the surrounding land. (Bottom) Subsequent erosion has flattened the landscape surrounding the large graben. The Riley Mountains developed from this type of fault action and erosion.

Cross Section, Balcones Fault to Eastern Llano Region: The action of faults had a profound effect on the landscape to the west of the Balcones Fault Zone. Immediately to the west of the Balcones Fault, Cretaceous limestone is exposed at the surface. Around Spicewood, much older rocks are exposed, a result of tectonic activity associated with the Ouachita Orogeny. Fault activity along the Llano Fault Zone raised the area. Subsequent erosion removed the material, but the Riley Mountains were protected from subsequent erosion by being part of a large graben.

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Mexico surrounded the area. Both of these were regional events, affecting vast areas. During the Pennsylvanian Period, around 310 mya, in connection with the Ouachita Orogeny, the Llano Fault Zone was activated throughout the Llano Uplift. Tension produced normal faults, creating a horst graben landscape. “Graben” is German for “ditch,” and “horst” means “high place.” Graben blocks dropped down, leaving adjacent blocks, the horsts, standing higher. The Riley Mountains in eastern Llano County comprise a large, complex graben. Rocks that dropped down now stand as high country after erosion of the surrounding landscape. The Riley Mountains are visible toward the horizon from the summit of Enchanted Rock. Another major fault just to the west of Marble Falls has brought Town Mountain granite (basement rock) in contact with Marble Falls limestone of Pennsylvanian age. A hop across that fault line takes you from rock more than 1 billion years old to rock 300 million years old, a difference of 700 million years. Ironically, a cross section reveals that much of the Llano Region topography is lower than the surrounding area, which is why the term “basin” is often used to describe the area. The Llano Basin is simply land that has been excavated by the action of the Llano River, Sandy Creek, and other tributaries of the Lower Colorado River. The erosion accelerated as a result of development of the Edwards Plateau. The tributaries have removed rock created during the Cretaceous, Pennsylvanian, Ordovician, and Cambrian periods, exposing older rock. Around the edge of the Llano Basin is an escarpment

retreating laterally over time. Much like the Grand Canyon, rocks from a wide variety of time periods are exposed in the escarpment (not the Balcones Escarpment) and in remnants in and around the Llano Basin. The term “Central Texas Mineral Region” refers to the economically valuable minerals found within the area.

Enchanted Rock Batholith Subduction takes crust and the solid bits of the upper mantle to great depths, where heat and pressure melt the source rock. Minerals that melt at lower temperatures, light-colored and rich in potassium and sodium, separate from the remaining dark-colored minerals rich in iron and magnesium. The resulting low-density magma moves upward into fractures in the solid but brittle crust, there to accumulate as enormous masses known as batholiths (Greek for “deep rock”) or plutons, which have dimensions of kilometers across and perhaps a kilometer or so thick. Enchanted Rock SNA sits at the southeast edge of the Enchanted Rock Batholith, a teardrop-shaped mass extending approximately 12 miles (20 kilometers) to the northwest of the park. Other features such as Dutch Mountain, Watch Mountain, and Bullhead Mountain, which are visible from the top of Enchanted Rock Dome, are all part of that same batholith. The surface area of the Enchanted Rock Batholith is 260 square kilometers. A geologic surface map shows the Lone Grove Pluton, Legion Creek Pluton, Katemcy Pluton, and many others. Some are concealed beneath sedimentary strata.

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E LEvATI ON PROFI LE #1

E LEvATI ON PROFI LE #2

Cross Sections, Llano Region: The Llano Region, often referred to as the Llano Uplift, is actually lower topographically relative to the surrounding land. The cutting action of the Llano River and its tributaries has carved out Cretaceous Period and older deposits in the area, as shown in these two cross sections through Enchanted Rock SNA, labeled Elevation Profile 1 and Elevation Profile 2 on the map. Rock around the perimeter of the Llano Region is Cretaceous limestone.

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Surface Rock in the Llano Region: Exposed surface rocks across Central Texas offer a fascinating study into the geological history of the area. Around the rim of the Llano Region are Cretaceous Period rocks (shown here in greens). Next down are the Pennsylvanian deposits (blues), followed by the Ordovician (pinks) and Cambrian (browns) deposits. Where all sedimentary rocks have been removed or were not deposited, igneous (reds) and metamorphic rocks (purples) are exposed.

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Granite

A Batholith and Associated Features: Xenoliths become trapped around the periphery of a batholith. Dikes radiate outward from the batholith, cutting across other rock formations. Sills squeeze in between rock formations. Laccoliths are similar to sills but push upward on the upper formation, creating a dome feature. Host rock near the batholith is locally metamorphosed. At Enchanted Rock SNA, all of the overlying rock was removed through erosion, leaving a relatively flat surface today where Precambrian rock is exposed.

The rock surrounding a batholith is known as host rock, and it is older than the rock making up the batholith. Host rock immediately adjacent to a batholith is known as wall rock. Magma squeezing into fractures crystallizes into sheets called dikes. Dikes that reach the surface are known as pipes, and they extrude lava, gases, and ash to create a volcanic field. A sill is an irregularly shaped pool of magma wedged between older geological layers. A laccolith is similar to a sill, but the area above the sill has bulged upward into a dome, deforming the overlying material. A stock is a large contiguous pluton formation less than 100 square kilometers in area (about 40 square miles).

When magma cools and solidifies below ground, it creates plutonic igneous rock (from “ignis,” Latin for “fire”; “plutonic” is from the Latin for “underground”).4 Depending on temperature, pressure, rate of cooling, and percentage of water, one of three broad classes of rock can be created: gabbro, diorite, or granite. The presence or absence of particular minerals, along with their percentages and crystal size, can be used to categorize further the type of rock created. The Enchanted Rock Batholith consists of granite. Granite magma is very viscous, resembling the consistency of toothpaste. As the surrounding host rock is a poor conductor of heat, the magma cools very slowly over millions of years so that large crystals, centimeters across, have the opportunity to form. Humans cannot directly observe granite in the making. In the laboratory we can simulate the high temperatures and pressures found deep underground, but we cannot wait patiently for a million years, watching granite magma crystallize. Research on an intrusive igneous rock in Brazil indicates that cooling had occurred at a rate of 36°C per million years. Granite is an assemblage of mostly lightcolored and low-density minerals. Their texture (the sizes, shapes, and relationships to one another) may be complex, but the list of minerals is quite short: potassium feldspar,5 pink or white in color; sodiumrich plagioclase feldspar (also called plagioclase), a nondescript dull white; quartz, gray when within a granite matrix, otherwise

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transparent to translucent, with a greasy luster; and biotite mica (also called biotite), with dark or black crystals that flake into thin sheets. Potassium feldspar endows the granite at Enchanted Rock SNA with its pink color. A small amount of hornblende may be present, along with trace amounts of zircon and other minerals. Depending on conditions in the magma, one of the feldspars or quartz may be the first to crystallize, leading to different mineral textures. Biotite and quartz usually crystallize at lower temperatures. Minerals that crystallize at lower temperatures, such as quartz, tend to be more stable at the surface of the earth. Indeed, quartz is highly resistant to weathering, and it is a major component of many sands found around the world. The rate of cooling is a primary factor in determining how large crystals will grow. A slow cooling rate, along with the presence of water, encourages crystals to grow larger, and this situation pertained at Enchanted Rock SNA. Within the Enchanted Rock Batholith, crystals of potassium feldspar got a head start and grew to a large size. The large crystals are called phenocrysts and are embedded in a matrix consisting of smaller crystals made up of the remaining mineral components of granite (and could include additional potassium feldspar crystals). Granite with phenocrysts embedded in a matrix of smaller crystals is said to be porphyritic. Subtleties in the percentage of minerals allow geologists to categorize granite further. Tracing a line from Enchanted Rock SNA to the northwest across the heart of the Enchanted Rock Batholith,

one will find leucogranite, granite, monzonite, granite again, grandiorite, monzonite again, leucomonzonite, and still more monzonite, grandiorite, and granite. Sand-sized crystals of zircon incorporate minor amounts of parent uranium (238U), a radioactive element, which through radioactive decay is transformed into daughter lead (206Pb). By measuring the ratio of parent to daughter atoms, the age of rocks can be determined. By this procedure, the age of the Enchanted Rock Batholith has been determined to be 1.08 billion years.

Town Mountain Granite The domes at Enchanted Rock SNA consist of Town Mountain granite (or TMC, for Town Mountain [Granite] Complex), named after a hill near Town Mountain (site of a quarry), a short distance west of Marble Falls, Texas. Granite in the TMC comes in four basic varieties based on color and grain size: gray coarse-grained, gray medium-grained, pink coarse-grained, and pink medium-grained. Variations may be found between or within batholiths, but the chemical and mineral compositions of pink or gray granite are nearly identical. Most granite at Enchanted Rock SNA is of the coarse-grained pink variety, differing in subtle features of color or texture from other granite in the Llano Region.

Features of Granite As magma crystallizes, fractures form as a result of the cooling. The remaining magma can be injected into the fractures,

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forming dikes within the larger granite body. The line of contact between dike and granite is typically quite sharp. The composition of the magma, along with the rate of cooling and the presence of water, determines the type of dike created. A slower rate of cooling, along with more water, is generally thought to lead to larger crystal size. A higher rate of cooling leads to smaller crystals. Material that cools relatively rapidly and is granitic in composition crystallizes into aplite dikes. Aplite dikes have a uniform and smaller crystal size, somewhat sugary in appearance. Often, little clusters rich with larger quartz crystals can be found along the dike. The smaller and more uniform crystals in aplite dikes weather more slowly than the surrounding granite. Magma that cools relatively slowly and is granitic in composition forms pegmatite dikes. At Enchanted Rock SNA the pegmatite dikes consist primarily of potassium feldspar and quartz. Pegmatite dikes have

Town Mountain Granite: Town Mountain Granite is made up of four basic minerals: potassium feldspar (pink), plagioclase feldspar (milky pale white), biotite (black), and quartz (white and shiny, but appears darker when embedded in rock).

large, even huge, crystals. In some dikes in Brazil, the crystals of pegmatite are measured in feet. At Enchanted Rock SNA, pegmatite crystals are larger than those found in Town Mountain granite, maybe a few inches in size. Pegmatite dikes often weather slightly faster than the surrounding granite.

Aplite Dike: After the magma in a batholith cools and crystallizes, cracks develop, allowing new magma to be injected, which forms a dike like the dark bands shown here. Magma with a sugary appearance and a granitic composition is known as aplite, and a dike of it is known as an aplite dike.

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Pegmatite Dike: As with aplite, pegmatite is granitic in composition. Its crystals, however, are quite large, and the material favors potassium feldspar and quartz. The presence of water and the slow cooling rates allow the crystals to grow large. In this photograph, the individual crystals are a few inches across.

Quartz Intrusion: Intrusions and dikes are occasionally made up almost exclusively of quartz. The large white blob is pure quartz, approximately 14 inches across.

Aplite and pegmatite dikes can be found at Enchanted Rock SNA and throughout the Llano Region. Dikes consisting of rhyolite, the extrusive equivalent of plutonic granite, are also present in the Llano Region, as are dikes of nearly pure quartz. There is at least one such quartz structure at Enchanted Rock SNA, a little hill made up of large amounts of quartz. Solid crystals that are suspended in viscous magma can be aligned as the magma flows. If you look carefully, you can see flow foliation (a.k.a. phenocryst alignment or platy parallelism) in the potassium feldspar crystals near the edge of the Enchanted Rock Batholith. It is quite evident at Enchanted Rock SNA. Xenoliths (from the Greek for “foreign rock”), which are embedded pieces of host rock caught up within the granite magma, also may be aligned with magma flow. Xenoliths are more common in the outer areas of a batholith, where the magma has been in contact with the host rock.

Magmatic enclaves appear to have been blobs of magma from the same magma body, but with slightly different properties. The enclave remained distinct as it cooled. As with xenoliths, magmatic enclaves can also demonstrate flow foliation. Nongeologists may have difficulty distinguishing between xenoliths and magmatic enclaves. Schlieren are possibly xenoliths or magmatic enclaves, rich in biotite or potassium feldspar, squeezed and stretched into dark thin bands when the granite was crystallizing and flowing. Biotite-rich schlieren are typically restricted to the outer areas of a batholith; potassium feldspar schlieren has a more intermediate location.6 The long, roughly parallel dark streaks seen in many locations at Enchanted Rock SNA are biotite-rich schlieren.

Deformation and Metamorphism The piling up and thickening of crust at plate margins can compress, twist, stretch, ghistory eol o g y

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Flow Foliation: Crystallized grains of potassium feldspar aligned with the flow of magma before the magma completely crystallized. The red lines show the aligned potassium feldspar crystals.

and otherwise deform rock. Two common types of deformation are folding and foliation (not the same as flow foliation). Folding occurs when stress is gradually applied over time to rock while the rock is in a high-pressure and high-temperature environment. The effect of folding on

sedimentary rock is especially pronounced, where layers of sediment can be significantly folded. Foliation is an alignment of some of the minerals in the same direction. Deformation does not involve melting of the minerals making up a rock, but as rock becomes deeply buried and is subjected to higher pressures and temperatures, minerals that originally formed in a cool, low-pressure environment become unstable. A little of the rock melts, but most remains solid. The melted minerals are destroyed and their atoms reorganized into a new set of metamorphic minerals that are stable at high temperature and pressure. This process is known as metamorphism (from the Greek, meaning “to transform”). Metamorphism may be just a light touch, with only slight heating or deformation, and the metamorphic rock may retain some of the characteristics of the parent rock, such as its layering. Or metamorphism can change the rock so profoundly

Magmatic Enclave: A magmatic enclave is a piece of rock that has different properties from the surrounding granite. Unlike aplite or pegmatite dikes, which form after granite has crystallized and then fractured, magmatic enclaves develop before or in conjunction with the crystallization of the main body of magma. The dark area, approximately 3 feet in the longest dimension, is a magmatic enclave.

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Schlieren: The long, curved black streaks are schlieren, rich in biotite, and possibly formed from xenoliths or magmatic enclaves squeezed and stretched into seemingly impossibly thin bands of rock as the Enchanted Rock Batholith flowed and crystallized.

that we cannot know for sure what type of rock it was originally. Minerals undergoing metamorphism go through a predictable sequence of transitions. Metamorphic grades characterize the occurrence of key minerals as the temperature increases. Low-grade metamorphism occurs at temperatures between 100°C and 350°C, medium-grade between 350°C and 550°C, and high-grade at temperatures above 550°C and below 900°C.7 Others use the terms “greenschist,” “amphibolite,” and “granulite” to correspond to the low, medium, and high grades of metamorphism. Facies, zones, metamorphic sequence, and other schemes not described here are also

used to characterize the degree of metamorphism, conditions, or minerals created or transformed. Two common metamorphic rock types are schist and gneiss (pronounced “nice”), and both of these are descriptive terms that do not imply particular origins. Schist is a medium-grade metamorphic rock that is rich in biotite or muscovite mica. It plausibly could have started out as mudrock (sedimentary), but schist can result from the metamorphism of volcanic rock and other rock types. “Gneiss” is an even more general term that refers to any high-grade, commonly strongly deformed metamorphic rock. Both schist and gneiss are ghistory eol o g y

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valley Spring Gneiss: In most locations within the Llano Region, rock of the valley Spring Domain has a vaguely granitic appearance, but in others, such as this site outside the park, in Mason County, it has the twisted banding characteristic of gneiss.

abundant across the Llano Region. Small exposures of schist and gneiss are present at Enchanted Rock SNA. Regional metamorphism occurs over a broad area deep below mountain ranges, where large areas of rock are deformed and metamorphosed. Contact metamorphism occurs in host rock in the immediate vicinity of intrusions of a batholith or dike. It can diminish rapidly over a small distance, sometimes less than a few feet from the point of intrusion. The area surrounding the intrusion where metamorphism is evident is called the aureole. Plutonic igneous rock that crystallizes and is deformed soon thereafter by ongoing regional metamorphism can be subjected to syntectonic (or synchronous) metamorphism. There are examples of low-grade syntectonic metamorphism in the Midway Sill, Grape Creek Pluton, and possibly Lost Creek gneiss in the Llano Region.

Contact Metamorphism: A wide pegmatite dike (on the left) is in sharp contact with highly metamorphosed darker rock, probably Packsaddle schist.

Rodinia and Grenville Orogeny What processes led to the creation of the Enchanted Rock Batholith and other plutons around the Llano Region? What was the environment like leading up to the creation of those features? Geological events over the course of more than 1 billion years have radically altered the landforms on Earth, making research challenging, but the geological interpretation continues to solidify with more research, and the current interpretation goes as follows. Starting roughly 1,400 mya during the Mesoproterozoic Era of the Proterozoic Eon, and over the course of the next 300 million years, primitive plates, or cratons, which would later become the core of the continents we know, came together, forming another supercontinent known as Rodinia. Reconstructions of Rodinia are

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Rodinia: The plates shown here began to move together to form the supercontinent of Rodinia roughly 1,400 mya. Their movement led directly to the development of batholiths exposed in the Llano Region, including the Enchanted Rock Batholith. The history and location of intervening crust is not currently known.

still early in their development, with research ongoing. Mountain ranges rose where the plates were stitched together, including along what would become the Eastern Seaboard of North America, far northern Mexico, Scandinavia, South America, Antarctica, Australia, India, Africa, and, most important to our story, in Texas over the presentday Llano Region and extending east and west from there. The late Precambrian mountain-building event is known as the Grenville Orogeny.8 Amazonia, to become part of modernday South America, collided with protoLaurentia, forming the Adirondack Mountains in New York State and other mountains extending into Canada and Greenland. The effects of this collision could have been felt as far as Texas. Antarctica, located at that time off the modernday western coast of North America, could

have interacted with proto-Laurentia, but it is unlikely that it collided with Texas. The Kalahari protocontinent, a component of the future African continent, appears to be best positioned, but it has been placed no closer than 1,500 kilometers south of proto-Laurentia. Other continental blocks, including the Rio de la Plata (another part of South America) and Baltica (part of Europe) have been suggested as possible candidates. To date, no continental block has definitively been identified as the culprit, so we will refer to this unknown fragment as the Southern Continent. Starting around 1,360 mya, the Southern Continent approached the Texas coast from quite some distance. As it approached, a subduction zone formed along plate boundaries under the sea separating the continents. Deep below ground, pools of magma formed plutons above the melt zone. Starting around 1,326 mya, magma made its way through the oceanic crust and formed a volcanic island arc. Around 1,292 mya, the approaching Southern Continent collided with the volcanic island arc, deformation and metamorphism occurred, and the volcanic island arc was sutured as a terrane onto the Southern Continent. Around 1,275 mya, volcanic and metamorphic activity ceased on the volcanic island arc, and the Southern Continent continued its movement toward Texas. We will temporarily label the rock making up the volcanic island arc as Domain 1. The conditions along the proto-Laurentia continental margin through the Llano Region 1,300 mya are poorly understood. The basement rock north and east of the Llano front (and deep below the surface today)

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Southern Continent Approaches Texas: Approximately 1,300 mya, a Southern Continental fragment (Kalahari Craton, Rio de la Plata Craton, or another) approached Proto-Laurentia. Its approach led to the development of a volcanic island arc over the converging oceanic crust. volcanic activity also occurred along the Laurentian coastline, as the result of a separate subduction zone off the Laurentian coast. The continued advance of the Southern Continent led first to the collision and destruction of the volcanic island arc and ocean basins, then to collision between the continents, along with the development of a massive mountain range over today’s Enchanted Rock SNA area.

is rhyolite and granite from 1,400 mya to 1,300 mya. To the south and east of the Llano front, extending into the Llano Region, is gneiss with an unknown source rock and metamorphosed sedimentary rock, with the oldest known rock dated to 1,366 mya. We will temporarily label the original continental rock in the Llano Region as Domain 3. Sometime around 1,275 mya, shortly

after the volcanic island arc fused with the Southern Continent, a new subduction zone formed between the Southern Continent and proto-Laurentia. A continental margin volcanic arc formed along the Laurentian coastline, very near or through the Llano Region. Between 1,255 mya and 1,232 mya, magma rose up above the melt zone and pooled, triggering volcanic activity along the coastline. Weathering and erosion of newly extruded volcanic rock, volcanic ash, and other pre-existing continental rocks brought sedimentary deposits to the protoLaurentian coastline and extending out into the shallow sea. Parent rock making up the deposits has been dated to 1,274–1,243 mya. The rock from the marine environment will be referred to as Domain 2. As the Southern Continent approached Laurentia, material from the shallow sea was compressed and deformed. Deformation took place along the Laurentian continental margin; also deformed were the plutons that had formed beneath the Laurentian continental margin volcanic arc. Then, approximately 1,150 mya, the Southern Continent, along with the fused volcanic island arc and intervening marine material, crashed into proto-Laurentia, leading to massive deformation, regional metamorphism, and uplift across the Llano Region. The abrupt boundary between the former volcanic island arc and the former marine deposits saw the maximum deformation and metamorphism, especially on the Laurentia side of the suture. As the continental crust thickened to as much as 90 kilometers, temperatures approaching 750°C and moderate to high pressures led to a high grade of metamorphism, which

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tapered off with distance from the collision zone. As the collision proceeded, the former volcanic island arc (Domain 1) was thrust slightly up and over the former marine deposits (Domain 2), which themselves were thrust slightly up and over the former continental margin of Laurentia (Domain 3). The greatly thickened crust formed a towering mountain range above the Llano Region. Batholiths that had formed earlier from subduction underneath Laurentia were deformed and metamorphosed. Shortly after 1,120 mya, the continents were fused. Dikes, batholiths, and other magmarelated structures penetrated all three domains. From 1,120 mya to 1,092 mya a round of batholith crystallization began. Low-pressure metamorphism occurred throughout the region, probably as a result of emplacement of the batholith structures. Possibly, uplift took place as a result of unroofing, or erosion of the towering mountains above. Deformation in the form

of foliation developed in the newly crystallized batholiths. An extensive rhyolitic dike dated at 1,098 mya shows no signs of deformation, placing a possible boundary on the end of the low-pressure metamorphism. After 1,092 mya and continuing to 1,070 mya, batholiths were created, but without evidence of foliation. The Enchanted Rock Batholith crystallized at 1,080 mya. Largescale batholith creation ceased at 1,070 mya. Minor aplite and pegmatite dikes filled in cracks in the cooling and shrinking batholiths for a short time. No other igneous activity, deformation, or metamorphism has occurred since throughout the Llano Region.9

Llano Region Rocks How do we know that all of these amazing events affecting Central Texas occurred? Today, the only known evidence is found in three locations throughout the world: one is the Llano Region, and the others are

Texas Coastline Profile: As the Southern Continent approached Proto-Laurentia, a volcanic island arc formed in the sea between them. Additional volcanic activity occurred along the Laurentian coastline. Weathered or volcanic material was deposited into the sea, later to be thrust over the continental crust when the Southern Continent collided with Laurentia, becoming Packsaddle schist. Laurentian continental crust would be metamorphosed into the valley Spring Domain. The volcanic island arc would be left behind as the Coal Creek Domain after a rift zone developed between the Southern Continent and Laurentia, and the Southern Continent subsequently moved away.

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Rock Domains: The three Precambrian rock domains identified in the Llano Region are the valley Spring Domain (metamorphosed continental crust; shown here in yellow), Packsaddle Domain (likely metamorphosed clay deposits from a shallow sea; green), and Coal Creek Domain (metamorphosed remnants from the volcanic island arc; purple). Packsaddle schist has been thrust over valley Spring gneiss (light green). Batholith structures (pink) intruded all the domains.

small exposures in far West Texas and far northern Mexico. The descriptions here are limited to the rocks found within the Llano Region. Now let’s look at the metamorphic and igneous rocks across the Llano Region and how they relate to the sequence of events during the Grenville Orogeny. The rocks can be divided into three domains, roughly from southeast to northwest: Coal Creek Domain, Packsaddle Domain, and Valley Spring Domain. The Coal Creek Domain represents the complex remnants of the volcanic island arc that was fused to the Southern Continent (Domain 1). Exposed not far to the east of Enchanted Rock SNA, it is made up of Big Branch gneiss and the Coal Creek Plutonic Complex. Big Branch gneiss,

dated 1,326–1,301 mya, is a metamorphosed quartz diorite (similar to granite, but rich in quartz). It was a granitic batholith under the volcanic island arc and was subsequently metamorphosed into gneiss sometime before 1,290 mya. The Coal Creek Plutonic Complex, including Coal Creek serpentine (metamorphosed periodite with a little water added), is made up of rocks that are typically associated with material within the upper mantle. The rocks have been dated to 1,292–1,256 mya. The Packsaddle Domain is made up of deposits originally in the marine environment off the coast of Laurentia (Domain 2). It consists of a set of metamorphosed sedimentary and volcanic material. In abrupt contact and positioned to the northwest of the Coal Creek Domain, the Packsaddle

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Domain has widespread exposure in the Llano Region. The highest grade of metamorphism observed in the Llano Region is at the contact point between the Packsaddle and Coal Creek domains. Rocks in the Packsaddle Domain include Packsaddle schist, Red Mountain gneiss, Comanche Creek gneiss, and a few other granite sills and dikes. The rocks of Packsaddle schist itself are currently undifferentiated, with ages ranging from 1,274 mya to 1,243 mya, but it is thought to consist mostly of the metamorphosed remnants of clay (and possibly volcanic) deposits. (The term “Packsaddle schist” is often used to refer to all of the rocks making up the Packsaddle Domain). There are small areas within Enchanted Rock SNA along Sandy Creek where Packsaddle schist can be found. Red Mountain gneiss and Comanche Creek gneiss are metamorphosed granite intrusions, dated to 1,239 mya and 1,238 mya, respectively. The third, and most poorly studied, domain is the Valley Spring Domain (Domain 3). It is thought to be the remnants of the proto-Laurentian continental basement, possibly combined with weathered and eroded elements from the volcanic chain that formed as a result of the stitching together of Rodinia. Located to the northwest of the Packsaddle Domain, it consists of Valley Spring gneiss, Lost Creek gneiss, Inks Lake gneiss, and other highly metamorphosed rocks. The gneiss consists of metamorphosed microcline quartz and small quantities of biotite and hornblende. Some gneiss within the Valley Spring Domain may be as old as 1,360 years. Lost Creek gneiss is roughly 1,254 million years old. Inks Lake gneiss, found at the

swimming hole at Inks Lake State Park, is 1,232 million years old. Both the Lost Creek and Inks Lake gneisses were most likely metamorphosed granite. Another group of highly metamorphosed rocks, ranging from 1,150 to 1,130 million years old, probably correspond to the high-pressure and -temperature environment created as Laurentia and the Southern Continent collided. Valley Spring gneiss is not present at Enchanted Rock SNA. In all, five periods of metamorphism are recorded in Valley Spring gneiss. Numerous plutons intruded into all three domains starting at 1,120 mya. The earlier plutons were formed in conjunction with tectonic activity and show signs of syntectonic deformation. They include the Grape Creek, Legion Creek, Wolf Mountain, and Oatman (the oldest) plutons. One possibility is that the batholiths were being unroofed by erosion of the mountains overhead. Pluton formation that continued after 1,092 mya, as tectonic activity ceased,

Llanite: The small blue crystals are an unusual form of blue quartz known as llanite, thought to be exposed nowhere else on Earth except for a narrow dike to the north of Llano, Texas.

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includes the Lone Grove Pluton, Enchanted Rock Batholith, and the youngest, the Katemcy Pluton at 1,070 mya. These plutons show no signs of syntectonic deformation. Aplite, pegmatite, rhyolite, and quartz dikes that penetrated the cooling plutons can be found at Enchanted Rock SNA and throughout the Llano Region. Just north of Llano is a large undeformed dike, dated to 1,092 mya, known as the Llanite Quartz Porphyry Dike (or the Llanite Dike), containing intriguing blue quartz crystals. To date, it appears to be the only location in the world where this mineral has been found in its original host rock, as opposed to sands derived from some unknown host rock source).

Where Are the Mountains? Sometime before 1,000 mya, everything settled down as the Southern Continent remained fused to Laurentia. A gap of 450 million years in the geological record, referred to by geologists as the Great Unconformity, occurred after 1,000 mya, during which time there was little deposition onto most of the earth’s continents. The lack of deposition makes it difficult to determine conditions on Earth through this interval. Around 750 mya, Rodinia began to break up. Somewhere near the Llano Region, rifts developed and the Southern Continent drifted away from protoLaurentia. Remnants of the volcanic island arc (Coal Creek Domain) and former marine deposits off the coast of Laurentia (Packsaddle Domain) were left behind in Laurentia. The land eroded for 450 million years

without any deposition to slow it down. That is a long time, even in geological terms. Actually, erosion had attacked the tall mountains once they rose up. By 550 mya, at the end of the Great Unconformity, the towering mountain range, possibly originally as tall as the Himalayas, had been completely worn away, exposing the root zone of the mountain range, formerly miles below ground, at the surface. Then, sometime between 545 mya and 525 mya, continental rifting led to the Cambrian inundation, when a layer of sand (which would become Hickory sandstone) was deposited in nonconformity on the extremely weathered metamorphic and igneous basement rock. The inundation to some degree preserved the landscape from the Cambrian Period. Subsequent inundations would further protect the Cambrian Period landscape. Although quiet today, Central Texas experienced the effects of some of the most important geological events in Earth’s history. One such event, the assembling of the supercontinent of Rodinia starting 1,400 mya, led to the metamorphism of preexisting host rock, creation of a towering mountain range, and extensive thickening of the continental crust. As the crust deepened, continental rock melted and formed the Enchanted Rock Batholith and other plutons across the Llano Region. During 450 million years of erosion, the mountain range was worn down to small hills, similar to what is visible today in the Llano Region. Intervals of extensive inundations by shallow seas led to deposits of limestone and other sedimentary rocks, preserving and

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protecting the Cambrian Period landscape from 550 mya. The assembling of Pangaea created the Ouachita Mountain Range and, through a set of faults, lowered the land to the east of the Llano Region, helping to remove material within the uplift. The relatively recent Cretaceous Period inundation formed the Edwards Plateau. Topographically high places such as those found at Enchanted Rock SNA were possibly islands surrounded by the encroaching seas. Seismic activity along the Balcones Fault Zone during the Miocene Epoch formed the Balcones Escarpment. Subsequent accelerated erosion created the Texas Hill Country and continues to expose additional igneous and metamorphic rocks in and around the Llano Region.

Notes

1. Quasicontinuous activity along growth faults is slowly tearing the land apart along the Texas coastline. 2. The transition from crust to mantle is known as the Mohorovicic discontinuity, caused by a change in chemical composition of rock. It occurs anywhere from 5 kilometers below a

mid-oceanic ridge to 75 kilometers below the continental crust. It has been detected by measuring the speed of earthquake waves traveling through Earth. 3. Mountains developed in West Texas as recently as 70 million years ago during the Laramide Orogeny. Volcanic activity associated with this period occurred in the Balcones Igneous Province as recently as 84 mya, producing volcanoes immediately southeast of Austin. 4. Extruded magma, that is, magma that reaches the surface in the form of volcanic eruptions, has the same chemical composition as intruded magma, but rapid surface cooling produces different structural characteristics. 5. Similar or equivalent terms often used are “microcline,” “orthoclase,” or “K feldspar,” “K” being the chemical symbol for potassium. 6. The origin of schlieren is still debated among geologists. 7. Below 100°C, diagenesis may occur, but not metamorphism. Above 900°C, minerals melt completely. 8. "Precambrian," a commonly used term, refers to the eons before the Phanerozoic Eon. 9. A similar set of events, most likely also the result of collision with the Southern Continent, took place in West Texas around the same time, beyond the scope of this book.

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Granite Slabs: House-sized slabs, known as Pirate Rocks among climbers, are remnants of an exfoliation sheet on Little Dome.

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Weathering and Erosion

s

Large-scale geological events led to the creation of rock units around Enchanted Rock SNA and the Llano Region. Subsequently, weathering and erosion combined to break down the original landforms, transforming them into the landscape we find there today. Weathering is the mechanical and chemical breakdown of rock into its constituent parts. Rock can be broken down mechanically into smaller pieces, or decomposed through a chemical transformation replacing some minerals of the original material. It can take place as a result of the rock’s exposure to water, air, or other agents, such as attack by bacteria or algae. Weathering occurs at the surface and extends to the depth that groundwater reaches beneath the surface. The style of weathering depends on the mineral composition and mineral organization of the rock, the rock’s porosity and permeability, and the agents to which it is exposed. Water from rainfall is by far the most important weathering agent, performing mechanical and chemical weathering. Erosion is the removal of the weathered rock components, which are then transported to another place and deposited again.

Porosity and Permeability Every type of rock has porosity and permeability characteristics, which determine how weathering attacks the rock and breaks it down. Porosity is the percentage of the volume of a rock that consists of voids. Pore space can be (1) between individual grains, (2) as a result of fractures, (3) from solution activity that dissolves the rock, and (4) from vesicles (bubbles) in the rock present from the time of its creation. Some rock, such as certain types of limestone, can be highly porous, and it can become more so through solution activity. Granite, on the other hand, is porous only because of cracks near the surface, which allow water and air to penetrate into the rock. Permeability is the measure of the ability of a material to transmit a fluid such as water. For this to happen, pores must be connected. If the pores are not connected, the rock will have low permeability and will not transmit fluids rapidly or at all. A porous rock might not be permeable, but a permeable rock has to be porous. The extremely slow movement of water through

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many types of rock is driven by gradients in hydrostatic pressure. Variations in the level of the water table drive water to travel very slowly through connected pores in the rock. Most limestone is somewhat permeable and can become highly permeable from prolonged contact with the corrosive effects of groundwater. Sandstone can also be permeable if the sand grains are lightly cemented together. Permeability in granite, on the other hand, is almost entirely provided by fractures, which normally die out a short distance below the earth’s surface. Aquifers and springs develop in highly permeable limestone and sandstone, especially where a low permeability rock layer is adjacent to a highly permeable layer, creating a barrier for the body of underground water. The San Saba–Ellenburger Aquifer, a minor aquifer of Texas, has an interesting footprint that corresponds closely to the Llano Region. This aquifer, which resides in the formations of the Ellenburger Group laid down in the Ordovician Period, basically surrounds, but is not found in, the heart of the Llano Region, where granite and metamorphic rock dominates.

also play a role, helping to fracture rock, which increases the rock’s permeability and therefore the ability of water to penetrate the rock. Wind abrasion (ablation) is a form of weathering that plays a role in dry deserts, but its effect is negligible in most places, including Central Texas, because the effects are very slow and are overwhelmed by faster water-driven erosional forces.

Ice Wedging and the Freeze-Thaw Cycle A powerful mechanical weathering force is ice wedging, which occurs as part of the freeze-thaw cycle. Rainwater permeates into pores or fractures exposed on the surface of rock. In highly permeable rock, such as Edwards limestone in Central Texas, water can penetrate deeper into the rock. In a low-

Mechanical Weathering Mechanical weathering is simply the breakdown of rock into smaller pieces, with no chemical change to the rock. Smaller pieces include boulders, stones, and grains, in decreasing size. Important mechanical weathering processes are ice wedging and abrasion. Only in extremely dry places, such as deserts, does ablation play the dominant role. Thermal expansion and contraction through temperature changes

Freeze-Thaw Cycle: Weathering, especially through ice wedging, is powerful enough to crack boulders the size of large buses, such as this one at Rock Clark Wall on Freshman Mountain. Extensive water staining is visible in the foreground.

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permeability rock, such as granite, only the surface pores are reached. In cold weather, water freezes and expands by about 9 percent of the volume occupied when in a liquid state. The expansion applies great force to the rock, causing small chips and flakes to break away. Often chips break away after temperatures warm back above freezing and the ice melts. Occasionally the force of expansion fractures large boulders. Development of fractures increases permeability and leads to an accelerated breakdown. Ice wedging is an important mechanism responsible for the breakdown of granite at Enchanted Rock SNA. Rainfall penetrates the surface of the granite, and if a freeze occurs, surface particles can be broken off, creating a coarse soil made up of small stones, known as grus. Grus, which looks like sharp-edged gravel, consists of the individual mineral crystals from granite, as the break typically occurs at weak areas along crystal boundaries. The primary minerals in grus are potassium feldspar and quartz.

Creek at the downstream edge of the park contains a variety of particles ranging from boulders to marble-sized stones to sand grains.1 Water flow down Sandy Creek during stormy periods sorts the particles by size, as smaller particles are more easily carried away during periods of low flow. At the mouth of the Lower Colorado River, small sand-sized particles are dumped into the Gulf of Mexico, providing material to build beaches and extend the land into the sea.2 Sand particles on the beach or in the ocean continue to be attacked via wave action.

Roundedness through Weathering The flat face of a particle (boulder, stone, sand grain) can be attacked from one side, an edge from two, and a corner from three.

Abrasion Abrasion is a mechanical attack that occurs as stones, sand, and sometimes even boulders bump and grind against one another, primarily as they are transported via streams. Particles in general become more rounded with the effects of abrasion. At Enchanted Rock SNA, grus around the base of boulders, especially on the domes themselves, is quite coarse. Grus in the streambed of Campside Creek, which runs near the campground, demonstrates the beginning effects of abrasion, making them less angular. The streambed of Sandy

Weathered Granite Boulder: Lichen, water, ice, and even plants are attacking this well-rounded boulder, a demonstration of spheroidal weathering. The boulder is even being attacked from below by the flow of water beneath it.

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Weathering at a corner is greatly accelerated in relation to weathering on the face of a particle. This leads to an elimination of edges and corners and a general trend toward an ellipsoidal (egg) or spheroid shape.3 The effect occurs throughout the range of particle sizes, from boulder to stone to sand grain. Abrasion and ice wedging round particles subjected to water flow and jostling, but cracking of particles by ice wedging could once again produce edges. A fracture in a boulder caused by ice wedging could produce a sharp edge, but over time the edge will be attacked and rounded.

Geologists’ Interpretations Geologists make interpretations of the conditions that a population of particles was subjected to, such as overall stream velocity (which indirectly determines the slope of the landscape), distance of travel, or wave action. Such interpretations are often only relative to another population, which had a similar point of origin but traveled a different route, say via a different stream system. Keep in mind that particles continue to be subjected to other types of weathering as they are transported, which can increase or decrease the degree of angular appearance and make interpretation more challenging. Analysis of the history of a population of particles can be quite complex, but general conclusions are possible.

Chemical Weathering In chemical weathering, the original minerals in a rock are altered and even

destroyed through transformation into a new set of minerals or dissolved components. Important chemical weathering processes are hydrolysis, hydration, dissolution, and oxidation. Once a mineral is chemically altered, parts can be washed away in solution. What remains is often more susceptible to mechanical weathering because of the increase in permeability, as the mineral grains no longer bond to one another.

Hydrolysis Water is an effective reactive agent (a catalyst) that can lead to chemical change in the minerals present. Hydrolysis is the chemical union of water with particular molecules in a mineral, allowing the water molecules to steal away surface molecules in the mineral, thus forming new minerals. One common reaction is the conversion of plagioclase feldspar, one of the key constituent minerals of granite, into kaolinite (a type of clay). Most types of clay occupy a larger volume of space than the original mineral because of the addition of water. The expansion results in associated mechanical weathering. Chemical attack and transformation of plagioclase feldspar and biotite remove these minerals from the granite matrix. Examination of mushroom rocks around Enchanted Rock SNA reveals the results, in the rough, crumbly rock faces made up primarily of potassium feldspar and quartz. Chemical weathering of Packsaddle schist and many other rock types in the Llano Region produce various clays also.

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Hydration (Reaction) Some minerals absorb water between naturally occurring sheets of atoms. The effect is known as hydration (or the hydration reaction). Unlike hydrolysis, where there is cleavage of the mineral when water steals molecules away, no such cleavage takes place during hydration. Water instead insinuates into the crystalline structure, which remains intact. Biotite is highly susceptible to hydration, which transforms the mineral into vermiculite. Some materials expand greatly when they are hydrated, leading to a subsequent mechanical force.4

Dissolution (or Carbonation) The water molecule is a universal solvent. It is capable of breaking chemical bonds, even strong bonds holding atoms together in a mineral crystal. Ever-present water carries extracted ions away in solution. Carbon dioxide gas (CO2), a trace constituent in the atmosphere, dissolves in water, forming carbonic acid, which enhances the chemical weathering process. Limestone is especially susceptible to dissolution, even deep underground if the water can circulate along fractures, dissolve rock, and increase permeability. If the limestone is very pure, no solid components or soil remain after dissolution. More often, the limestone contains impurities such as clay minerals, which do not dissolve as readily, leaving a thin residual soil. The vast majority of the Texas Hill Country consists of exposed limestone with little or no soil at all. An entire karst landscape can be created chiefly through the process of

water dissolving rock. Karst topography is full of sinkholes, caves (some of them collapsed), and even underground permanent streams. Longhorn Cavern, at the eastern edge of the Llano Region, is a place where water has penetrated deep into limestone. Dissolved mineral material can be precipitated somewhere else as travertine (calcium deposits), such as that found at Gorman Falls in Colorado Bend State Park. It can also be precipitated in the ocean, where the resulting ooze can be compressed once again to form new limestone. The rocks recycle, one rock type becoming another, or even becoming the same rock type again. Plagioclase feldspar is also susceptible to the effects of carbonic acid, but to a much lesser degree than limestone.

Oxidation When a mineral breaks down by chemical weathering, its dissolved constituents can combine with atmospheric oxygen in a process known as oxidation. If a mineral contains iron, oxidation can transform it from a brown or bottle-green color to tan, brilliant orange, or deep red. Limestone contains little iron, but the oxidation effect is spectacular in glauconite, an ironcontaining variety of clay mineral that is abundant in the Llano Region in the form of Lion Mountain sandstone.5 Weathering transforms green glauconite into reddish brown hematite, an iron oxide mineral. Solutions that contain iron can travel some distance and then precipitate hematite in the pores of sandstone, in some cases helping to cement the sandstone together. Deposits of iron ore in the Llano Region exist

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in small pockets of the Valley Spring Complex. Hickory sandstone, another common rock found in the Llano Region, contains nearly enough iron to make it economical to mine.

Regolith Regolith is the complex soil originating from weathered rock material and plant material that has not yet been transported.6 Regolith can be hundreds of meters thick, and either widespread or highly localized and confined to a small area. Across most of the Texas Hill Country, regolith, even if widespread, is often only a few inches thick. In such areas, ranching is possible but farming would be futile. The character of regolith often changes with depth, with different types of soils as you go deeper. Grus collects in weathering pits on the domes of Enchanted Rock SNA, supporting an intriguing but small set of plants and animals. The grus piles up much deeper along the flanks and at the base of the domes, supporting large trees and other plants. Potassium feldspar and quartz, along with kaolinite or vermiculite and organic material, form soil. Potassium feldspar creates a slightly acidic soil from the potassium, a chemical element critical for plant growth. Crumbly alluvial deposits along Sandy Creek consist of transported grus, decomposing organic material, and other materials from other nongranitic rock formations transported from upstream of Enchanted Rock SNA. Only at low elevations does much organic material appear. Deeper and more complex regolith supports abundant, diverse, and potentially

larger plant life. Similarly, as limestone dissolves and releases calcium ions, highly alkaline soils develop. Because granite and limestone produce soils with very different properties, they support different plant communities. Areas with dominant granite-derived (or sandy) soils in Texas support the post oak plant community, and areas with soils derived from limestone support other plant communities. Packsaddle schist, Lion Mountain sandstone, Hickory sandstone, and other Llano Region rocks each produce soil conditions supporting different plant communities.

Erosion So where does all of the stuff go after it has been weathered? Erosion, a term we casually tossed about in the “Geology” chapter, is the process of removing weathered rock from its place of origin and transporting it to a point of deposition. Erosion attacks high elevations more vigorously, lowering the elevation of the landscape, but it also can proceed laterally (sideways) in the form of a retreating escarpment or hillside, as is occurring in the Llano Basin. On a larger scale, the Enchanted Rock Batholith began deep in the roots of a huge mountain range built during the Grenville Orogeny. That range was completely eroded away by 450 million years of relentless weathering attack. After the Great Unconformity, during which erosion forces dominated over much of the world, parts of the Enchanted Rock Batholith and surrounding deep-seated metamorphic and granitic rocks were at the surface, but then the

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Cambrian Period Hickory sandstone was deposited by streams flowing into the sea, helping to protect and preserve the Cambrian Period landscape. That landscape, before deposition, could have resembled today’s Llano Region landscape. Subsequent deposition during the Ordovician, Pennsylvanian, and other periods only buried things further, with intervals of weathering and erosion between the inundations. Mountains created during the Ouachita Orogeny pushed everything relatively upward, helping to form towering mountains just to the east of the Llano Region. The mountains were once again completely weathered away in almost all of Texas, and erosion carried all the material to the sea, west and east. Depositions such as occurred during the Cretaceous Period were extensive but shallower in places where the landscape remained topographically high, as in the Llano Region. Subsequent erosion has, in places, once again exposed the preserved landscape from 500 million years ago.

Isostatic Balance and Adjustment How did the Enchanted Rock Batholith, which was once deeply buried under a towering mountain range, get to the surface? Even over hundreds of millions of years of the Great Unconformity, it is still a little difficult to imagine how these deep-seated structures could have made their way to the surface. Major mountain ranges are similar to icebergs, in that only 10 percent of an iceberg is visible above the ocean level, with 90 percent lying hidden below the surface. Just as ice is less dense than the

surrounding water that supports it, the mountain range consists of less-dense crustal rock that rests on more-dense mantle rock. The part that we see is like the tip of the iceberg, much smaller than the mountains’ root zone, which could extend 50 miles or so into the earth. This situation does not persist indefinitely, because erosion is always at work. If ice melted from the top of an iceberg, the entire mass would rise, always maintaining the ratio of 10 percent above and 90 percent below water. Similarly, for every 100 feet of mountains eroded away, the root zone could rise as much as 80 feet in reaction to unroofing. The mountains make an isostatic adjustment to regain isostatic balance. The tendency of mountains to become less tall through erosion is therefore slowed. While being destroyed, mountains rejuvenate themselves. Rocks that crystallize at great depth, such as those in a granite batholith, migrate over time to the surface. As erosion proceeds, the topography is flattened and the rate of erosion and isostatic adjustment is slowed. Around the Llano Region, much erosion took place after the assembling of Rodinia and the associated towering Grenville mountain range. After tectonic activity subsided 1 billion years ago, there followed 450 million years of erosion, which reduced the once towering mountains to small hills, very similar to what we see today. All during this time, the Enchanted Rock Batholith approached and eventually reached the surface. Enchanted Rock and other batholith formations found around the Llano Region lost a great deal of material to weathering and erosion before the

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Cambrian Period inundation, which once again preserved the landscape.

Transportation and Deposition Rivers, streams, and creeks serve as the primary agents of erosion by transporting weathered material to the ocean. Streams remove material, reducing the landscape, but they can also deposit sediment. Upon reaching the ocean, a river deposits its load of sand and mud at the mouth, forming a delta. The deposition extends the shoreline outward over time, creating more land at the expense of the sea. The Texas coastline has numerous times been extended from the Llano Region to the south and east. Today, water and sediment from Enchanted Rock SNA enter Sandy Creek and Walnut Springs Creek, then flow into the Llano River, the Lower Colorado River, and to the Gulf of Mexico. Analysis of sediment shows that granite debris is present in Matagorda Bay but not at the mouths of other Texas rivers. Sediment makes its way to the ocean by fits and starts. The stream gradient, determined by the steepness of the land, greatly influences whether the stream at a given location is cutting downward or laterally. Steeper gradients lead to faster downcutting, headwater advance (where the headwaters of a stream move upland), and an increased potential to transport sediment. Less steep gradients lead to slower downcutting, increased lateral cutting, decreased potential to transport sediment, and increased deposition. During times of deposition a stream channel tends to wander laterally across its floodplain.

Stream Terraces: Streams flow out of the mountains, downcutting valleys when the stream gradient is high. As the gradient lessens, the stream meanders, leaving stranded terraces above.

Braided Stream: Sandy Creek is a braided stream where the water has difficulty transporting the sediment load (coarse grus) under normal conditions. This causes the stream to break up into multiple small, temporary channels.

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Streams that cannot carry their load (through a combination of gradient and particle size) become braided. A large river such as the Mississippi, although its gradient is shallow in places, carries very small mud particles and meanders along its course. Sandy Creek, which runs on the south side of Enchanted Rock Dome and on to the Llano River, is often braided, as it typically cannot carry its load of coarse grus during periods of normal low water flow. In normal flow conditions, only fine particles and very small stones are transported downstream, along with dissolved mineral material. During flood events, larger stones and even boulders can be transported. Large particles tend to be confined to the stream channel, whereas smaller particles carried by water overtop the bank during time of flood. Streams perform 90 percent of their transporting work during floods. Chemicals dissolved in the water can cement stones of different sizes together to form conglomerate rock. Quartz sand grains, or other material, can also become cemented together, eventually forming sandstone. The stream gradient can change along the course of the stream until it reaches the ocean. The stream gradient can also change over time from erosion, changes in sea level, additional uplift, or subsidence along faults. The balance between erosion and deposition can alternate back and forth. Changes in stream gradient can transform the river from meandering to an interval of downcutting, or vice versa. As a stream downcuts, the meandering of the stream across the floodplain leads to

the development of terraces. Older terraces are found at higher elevations, younger ones as you descend to the modern floodplain. The terraces may not be paired on either side of the stream if erosion is not the same on both sides. Terraces can become stranded far away from the stream if the stream shifts course. Large flood events are especially effective in shifting the course of a stream. At the level of the modern floodplain, the river deposits part of the load it carries downstream along the streambed. These deposits (called alluvium) tend to shift over time as floods occur. On rare occasions, during large floods, the stream can leave deposits on terraces outside the floodplain. Throughout the Llano Region, especially in and around the Llano River, San Saba River, Colorado River, or other larger waterways, numerous terraces often exist, some quite removed from the current course of the river. The terraces create arable conditions in the few places where farming is possible in the Llano Region; otherwise, only boulders and stones could be harvested. At Enchanted Rock SNA, small terraces can be identified at places along Sandy Creek. For example, in the main campground, down by sites 9, 10, 12, and 13, there are up to three terrace levels, with the third level found where the bulk of the campsites are located. The floodplain consists of the grus-lined streambed and a terrace made up of grus and organic and inorganic material that supports a rich diversity of plants. It could be that the current slow downcutting taking place in and around Enchanted Rock SNA, along with the relative lack of an upstream river system, does

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not support the formation of additional terraces at this time. Maybe in some distant future, when the stream gradient is higher, conditions could change. The cycles of deposition and erosion, of creation and destruction, repeat and repeat. As the Cambrian Period inundation began, Enchanted Rock and other topographically high locations within the Llano Uplift probably stood as islands in the midst of a shallow sea, whose sedimentary deposition eventually overtopped them. A similar event occurred in the Cretaceous Period and possibly during other inundations. The tiny snippet of geologic time called “today” happens to be land-dominated, with small stream gradients, but it was not always so around Enchanted Rock SNA and the Llano Region.

Jointing While plutonic igneous rock at Enchanted Rock SNA remained deep underground for hundreds of millions of years, it cooled very slowly, maybe as slow as a few degrees for every 1 million years. During this time, erosion removed overlying rock, and the earth responded with isostatic adjustments, which encouraged more erosion and more uplift. At places, granite making up the Enchanted Rock Batholith neared the earth’s surface. As once deeply buried granite neared the surface, the removal of overlying rock relieved pressure that had been present since the batholith formed. Reduced pressure led to upward expansion, rather than lateral, as that was where materials were being removed. The effect is similar to bread dough rising up above its loaf pan as it is baked.

As the granite expanded, it broke into fractures called joints. Joints can be close together or far apart. They can also be close together in one direction but far apart in another. How the joints form depends on the mineral composition and organization within the granite, how it cooled, how fast it was unroofed, and many other factors that are quite complex and difficult to analyze. At the same time, during the long episode of uplift accompanied by erosion, the granite was cooling, which caused the rock to contract; contraction inhibits the formation of joints. The effects of reduced pressure and reduced temperature work in opposite directions; they are in competition. If uplift of a batholith was too rapid, lots of closely spaced joints would form, and the rock would crumble away once it was exposed. If uplift was too slow, the rock could contain almost no joints. A quarry that produces tombstone material or ornamental granite for a building such as the Texas State Capitol (granite from near Marble Falls in the Llano Region) depends on joints to allow readymade rectangular blocks to be broken out. Within a narrow range, the spacing of the joints in a quarry has to be just right so that the operation can extract large (but not too large) intact blocks, greatly decreasing the cost of preparing the granite for use as a building material. Areas that are relatively more heavily jointed are called fracture zones. At Enchanted Rock SNA, fracture zones are found around the periphery of domes and castle tors; the fracture zones are represented by valleys and the joint-free zones

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Jointed Zones: Fracture zones are found at the boundaries of exfoliation domes. The rock in these zones is, for reasons not fully understood, more easily fractured and weathered, preventing exfoliation sheeting or tor development. On this topo map of Enchanted Rock SNA, the black lines indicate the fracture zones, which appear to surround the domes.

by high-standing areas. Turkey Peak also has fracturing different from that found in the domes, possibly because of different rates of cooling or unroofing.

Sheeting Joints often have a preferred orientation, the cause of which is still something of a mystery. Joint development may be influenced by subtle variables, such as the foliation present in Town Mountain granite (discussed in the “Geology” chapter). “Sheeting” refers to jointing that is parallel to the land surface. The thickness of sheets can vary from a fraction of an inch to tens of feet. If the sheet is thin, weathering causes it to crumble and break up. A thick sheet may remain somewhat intact. Weathering can

undercut a sheet along the margin in a process called margin sheeting (or tafonic undercutting), leaving pockets and gaps that a person can crawl through. Margin sheeting is responsible for the development of most of the caves and crawl spaces at Enchanted Rock SNA. The gaps provide flow paths for rainwater. Often the rainfall runoff rate is greatly reduced as water makes its way between sheets. In isolated locations, a slow, steady supply of water can continue to seep out long after a rain event. Sheeting can be deceptive. It originates through jointing and weathering processes and the structure of the granite minerals, but it often makes homogeneous granite look as though it were made up of sedimentary layers, which alternatively originate by deposition.

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Exfoliation Dome Cross Section: An exfoliation dome is much like an onion, with exfoliation sheets peeling off the dome in thin layers. The sheets get thinner at the top of the exfoliation dome. The exfoliation sheets break up into slabs, which are attacked by weathering and eventually are reduced to grus or tumble into boulder piles at the base of the dome.

Exfoliation Domes Exfoliation domes are a much larger-scale weathering feature. An exfoliation dome requires a few special conditions to develop. First, the sheets must be thick enough to deter weathering and breakup. Second, the sheets must also be large enough and free of vertical fractures to allow the dome to rise without breaking up. In an exfoliation dome, parallel sheets pop off in concentric layers, rather like the structure seen in an onion that is cut in half. Internal (and somewhat newer) sheets deep within an exfoliation dome tend to be thicker, and sheets long exposed at the surface of the dome tend to be thinner. Exfoliation sheets tend to be thinner at the top of an exfoliation dome compared with the thickness of the sheets at the base of the same dome. The thinner part of the sheet at the top is more quickly eroded away, leaving larger, isolated boulders on the flanks.

The best-known exfoliation dome is Half-Dome in Yosemite National Park. Presumably once a complete dome, it was at some point cut in half by glaciers. HalfDome is one of a number of batholith

Half-Dome, Yosemite: Half-Dome is an exfoliation dome in Yosemite National Park, California, where an extensive set of young batholith formations makes up parts of the Sierra Nevada mountain range. Glaciers during the last ice age removed half of the dome, lending the feature its modern name.

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bodies in the Sierra Nevada Mountains, but on a larger scale. It stands roughly 4,750 feet above the glacier-carved Yosemite Valley. Enchanted Rock granite wins the prize for antiquity, being about five times older than the rock that makes up Half-Dome. (The rock of Half-Dome is roughly 200 million years old.) Exfoliation domes at Enchanted Rock SNA include Enchanted Rock Dome, Little Rock Dome, West Little Rock Dome, Buzzard’s Roost, Freshman Mountain, and Flagpole. Collectively, they and others in Central Texas are known as Bornhardt

(or domed) inselbergs (German for “island mountains”). The vertical jointing of exfoliation sheets leads to the formation of large, roughly rectangular slabs. Near the base of a dome, the slabs can be quite large, large enough to attract climbers to the park from around Texas. Weathering slowly transforms the slabs into spheroidal boulders. Continued expansion of the exfoliation dome widens the gaps between blocks, which encourages yet more weathering. Gravity causes joint-bounded blocks to creep very slowly down a gentle face or, on a steep face such as the north side

Exfoliation Domes: Flagpole Dome (in the foreground) and Buzzard’s Roost, Freshman Mountain, and Enchanted Rock Dome (from left to right in the distance) are all exfoliation domes.

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Exfoliation Sheets: Numerous large slabs are the remnants of an exfoliation sheet on the flanks of Enchanted Rock Dome. Many of the slabs retain somewhat sharp edges, as weathering has not had the time to attack them. Note the large, fractured boulder on the left, probably cracked from ice wedging. The boulders support flowers, shrubs, and even a few small trees where enough grus has accumulated and there is a reliable water supply.

Turkey Peak Castle Tor: A castle tor such as Turkey Peak (upper right) has a very different appearance from an exfoliation dome such as Enchanted Rock Dome. A greater degree of fracturing and, more important, fracturing that is not parallel to the ground level prevent sheets from remaining intact as expansion proceeds.

of Enchanted Rock Dome or the southwest side of Buzzard’s Roost, go into free fall.

of highly jointed boulders are found throughout the park.

Tors

Exfoliation Dome Development

Tors (a.k.a. koppe) are moderately to heavily jointed outcrops of igneous rock that are left standing above the landscape after erosion has removed surrounding material. Larger tors are referred to as castle tors (or castle koppe). Turkey Peak and Boundary Rocks at Enchanted Rock SNA are castle tors. Turkey Peak’s location on the margin of the Enchanted Rock Batholith has led to a great number of fractures, pegmatite, and other conditions that preclude development of an exfoliation dome but encourage tor development. Numerous other rock outcrop tors consisting

When did the exfoliation domes of Enchanted Rock develop—long ago or relatively recently? They are old features. Other locations in Canada and Antarctica, where rates of erosion are low, can be shown to have survived as distinctive landforms for hundreds of millions of years. Most likely, Enchanted Rock and other parts of the Llano Region were exposed by extensive erosion during the Great Unconformity but before the seas flooded the area at the end of the Cambrian Period. Ever since that time, the region has been quite stable, sometimes above sea level and subjected to

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Mushroom (or pedestal) rocks are formed by differential erosion of a block of granite

that originated in an exfoliation sheet. The top of an exfoliation sheet is often more resistant to weathering than the middle of the sheet. It is not clear why this is so, but it may be related to why the sheet joint formed at that location in the first place. Other theories suggest that the surface of a sheet is hardened through the weathering process. Whatever the mechanism, the top of a mushroom rock resists weathering while the middle of the block can be in an advanced state of decomposition. Weathering removes much of the plagioclase feldspar and biotite, more so from the middle of the boulder. Protruding crystals of potassium feldspar and smaller quartz that remain can be broken off with a light touch. Climbers avoid this rotten rock. Sometimes, the middle of a mushroom rock gives way, allowing the top to come crashing down. In the long run, all of the boulders will be reduced to grus and carried away.

Mushroom Rocks (Pedestal Rocks): The top of a mushroom rock is harder than the sides, allowing weathering to favor the sides. Eventually, the column cannot support the top, and the mushroom rock tumbles.

Emergence of a Mushroom Rock: As this mushroom rock emerges from a large boulder, the softer sides of the boulder are cracking and breaking away, but the harder top, which will become the cap on the mushroom, remains.

erosion, at other times below sea level with the resulting deposition of sediment. Enchanted Rock has been buried by sediment and then exhumed, and perhaps this has happened several times during the 450 million years since the Cambrian Period. The geological record is never complete enough to make absolute conclusions; only interpretations of the evidence are possible. Enchanted Rock has never been glaciated, even though its smooth contours resemble land that has been scoured by an overriding ice sheet, as was the case with granite exposed in northern Minnesota, extending into Canada. A small-scale protuberance such as a granite tor would have been no match for the massive erosional power of flowing ice.

Mushroom Rocks

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Gnamma: The surface of an exfoliation sheet has a natural wavy pattern. Where the granite is flat, water collects in the natural depressions for a short time after a rainfall. Over time, chemical weathering eats away at the granite, deepening the pit. A small opening is visible on the far side of this very shallow gnamma, where the water can exit down the gentle slope in a developing channel.

Doughnut: A doughnut is another form of weathering pit; its walls are unusually steep, allowing for more pooling of water. This photograph, looking like something from a Rolling Stones poster, has a gnamma below two doughnuts.

Weathering Pits, Doughnuts, and Vernal Pools Gnammas and doughnuts develop on granite and provide the habitat for many life forms that are specialized and unique to such locations. Gnammas and doughnuts are collectively known as weathering pits (or opferkessel, solution pans, weathering pans, panholes, tinajitas, kamenitza, or etched potholes) when dry. They are called vernal pools when wet. They typically occur near the top of exfoliation domes where the slope of the granite is relatively low, allowing water to pond. Gnammas start out as shallow variations on the surface of an exfoliation sheet. Often, they are quite flat-bottomed. Small flakes break off as a result of mechanical weathering, which deepens the depression.

Weathering Pit and Associated Dike: The presence of a narrow but quite long pegmatite dike (on the right) has influenced the development of this weathering pit.

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vernal Pool: A burst of plants and small creatures becomes apparent about a week after heavy rains fill these weathering pits. The effect is especially pronounced in the springtime. vernal pools may support a monoculture or a variety of plants, depending on the depth and composition of the soil, the amount of time that the water remains, the depth of the weathering pit, and other factors.

Acidic standing water chemically weathers and corrodes the gnamma. Mature gnammas can be tens of feet across. Doughnuts are similar to gnammas but have steep bounding walls that rise up above the surface of the doughnut. How a doughnut forms is unclear. Theories include hardening of the rock from mineral deposits in water, blockage of water flow from long-gone overlying boulders, and others. Many doughnut features seem to have fractures or small dikes nearby, which may somehow influence the weathering rate. Gnammas and doughnuts are extremely important features supporting unique life forms at Enchanted Rock SNA. Water trapped in larger weathering pits may persist for weeks after a rainfall, providing an invaluable foothold for life on the granite domes.

Grus accumulates in weathering pits, forming a thin soil sufficient to sustain plant growth for pioneer species. Near the rim of the weathering pit, finer material is washed away, leaving behind coarser material. Finer material remains and settles in the center of the weathering pit. Therefore the plants that take hold in the middle of the weathering pit are different from those at the edges. As plants die, they add biological material to the mixture. In some pits, especially the flat-bottomed ones, mud covers the bottom of the pit, supporting plants such as quillwort. More complex soil in the larger pits is better able to retain water and support a more advanced succession of vegetation. Only the deepest weathering pits can support small trees or shrubs. Fairy shrimp have adapted to the wet-dry cycle of the vernal pools. The abrupt blossoming of all sorts of plant and animal life after a rain is amazing, especially if their appearance is compared with the dry weathering pits seen during a previous visit to the park. Plants like the rock quillwort are also uniquely adapted to weathering pits.

Atent Caves Most Central Texas caves form in limestone through solution activity (karst caves). In contrast, the dozens of caves or crawl spaces at Enchanted Rock SNA are a side effect of the exfoliation process. Known as atent caves, they are typically small and confined near the surface. Occasional pockets are created as sheets of granite separate, break, slide, and are subjected to weathering and erosion, especially margin sheeting. Enchanted Rock Cave, the largest in the park, is roughly 600 feet long and is one of the history w eat hering a nd ero sion

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largest atent caves in the United States. It was formed through a number of processes, including fracturing, opening of pockets between exfoliation sheets, grussification, washout of pockets by heavy rains, and sliding of blocks onto the gap over the cave.

Tent Blisters Tent blisters (a.k.a. A-tents) develop in one of two ways. More easily understood is the situation where gravity causes individual blocks in a sheet to interact with one another as they slide down the flank of an exfoliation dome. Two adjacent blocks can exert force at just the right angle to buckle

Water Staining: Flowing water leaves mineral deposits on rocks. Staining can be confused with schlieren or lichen.

A-Tent Formation: When exfoliation sheets break up into slabs, they sometimes shift and butt up against each other. Infrequently, the angle of the shifting is just right to force the slabs together and into the air, creating A-tent formations. Ferns and other plants often grow under the A-tent structure, and lizards and other animals use the space for shelter. Notice the dark-stained track at the top of the photograph, where water flows under this A-tent formation, providing moisture to the wooly lipferns below.

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Channel: The cutting action of flowing water creates channels. Often, channels connect weathering pits, concentrating water resources and allowing plants to thrive in the otherwise inhospitable conditions on the granite flanks. In this particular photograph, taken during a light rain, water is flowing in the channels.

up into an arrangement that resembles a drawbridge. Another possible creation mechanism is more subtle. Variations in the surface of an exfoliation dome, the same variations that develop into weathering pits, sometimes result in a granite lip. Water flowing along the lip eats into it, creating a void through

a process similar to margin sheeting. At the same time, lateral pressure within the exfoliation sheet thrusts the area upward into a gentle curve. With enough pressure, the granite cracks, resulting in a similar drawbridge effect. Tent blisters, and other cracks and crevices, are conduits for water. They provide

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important sheltered areas where ferns can grow and lizards can thrive on the exposed granite exfoliation dome surfaces.

Water Staining Rainwater runoff from the flank of a dome, possibly in conjunction with bacterial activity, eventually builds up dark gray, green, or blackish mineral deposits known in the deserts of the American West as desert varnish, or more simply as water staining. Other organisms such as lichens or geological features such as schlieren or dikes might occupy the surface, superficially resembling water staining. Close inspection is required to identify water staining and the other features typically do not run vertically down the domes.

Channels Water flowing down the surface of an exfoliation sheet over a long period of time can cut a channel (or granitrillen, rill) into the surface. Channels exhibit a slight meandering pattern vaguely similar to that found in a stream. Channels can range from almost no depth to as much as 8–10 inches deep. Channels experience accelerated weathering, with removal of plagioclase feldspar and biotite, leaving behind polished potassium feldspar and especially quartz. Some channels are water stained, others not. Channels are often devoid of visible life, including lichens, as they are scoured by water flow. Channels frequently connect weathering pits together, creating a sort of water removal network that drains the exfoliation

dome. As weathering pits fill from water arriving from the channel above, they spill over their edges, sending water down another set of channels, possibly to another weathering pit below. Channels have an important effect in that they concentrate the water supply coming off exfoliation domes into the weathering pits and into small areas at the base of the dome. Such locations support a greater diversity of plant life. Channels should not be confused with dikes or fractures. Both dikes and fractures also help direct water down the exfoliation domes, but their origin is quite different. Mechanical and chemical weathering and subsequent erosion are responsible for the large-scale breakdown and removal of limestone and other deposits from the Edwards Plateau. That removal exposed small parts of the underlying Enchanted Rock Batholith, other batholith structures, and other older metamorphic rock. Large-scale weathering effects of the Enchanted Rock Batholith led to the development of exfoliation domes and castle tors. Small-scale weathering features, like doughnuts, gnammas, and channels, help retain water and form soil conditions that support life in a seemingly harsh environment. The water and soil conditions are responsible for the fascinating life found on the domes.

Notes

1. Some of the boulders, stones, and grains in the creek bed originate from other rock types upstream of the park, where granite is not the dominant rock.

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2. Much sediment remains trapped behind a series of dams along the Lower Colorado River. 3. Many minerals have a natural cleavage pattern that helps to maintain edges as weathering proceeds. 4. The thalloid tissue of lichen, which anchors the lichen to rock, is similarly

expandable in the presence of water through biological hydration. 5. Lion Mountain sandstone consists of sandstone particles possibly made up of trilobite excrement. 6. Colluvium is eroded material that formerly mantled a hillside but has crept downhill under the force of gravity.

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Echo Canyon Winter: A coating of sleet and snow gives Enchanted Rock Dome and Echo Canyon an unusual look.

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Weather

s

Weather plays a pivotal role in shaping the landforms and determining which plants and animals will thrive at Enchanted Rock SNA. If you were placed atop one of the domes of Enchanted Rock SNA without traveling through the surrounding Texas Hill Country, you might at first think you were in a desert or possibly even an alpine setting. Cactus, lichen, scattered stunted trees, grasses, and in-season flowers are found at the top of the mostly bald domes. Often there is not a cloud in the sky. Summertime high humidity levels and hot temperatures are a giveaway that you are neither in a desert nor in an alpine zone. In fact, Enchanted Rock SNA receives around 30 inches of rain a year. Ample rainfall intermixed with regular, extended periods of drought supports an interesting juxtaposition of Great Plains, subtropical, eastern woodland, coastal, and desert plants and animals. The frequency and size of rain events, along with the hot (but moderately so) subtropical weather and mild winters strongly influence what plants and animals are present, and when. Long-term weather patterns spanning months or even years greatly affect Central Texas weather. The patterns are caused by

large-scale regional or global phenomena that develop and then persist in the atmosphere. Some phenomena such as El Niño or La Niña have only recently been studied with enough rigor to begin to understand their effects on Central Texas. The end effects are regular extremes of weather, including frequent extended droughts, long periods of blistering heat, and occasional epic amounts of rainfall.

Temperature, Precipitation, Humidity and Heat Index Temperature Temperatures at Enchanted Rock SNA range from cool to stinkin’ hot. In general throughout the year, it is warm to hot in the daytime and pleasant to warm at night. From April through October, the average high remains above 80°F. July and August will typically see high temperatures above 90°F every day, and some days (many days in some years) exceed 100°F. Many animals, including most mammals, avoid the hottest part of the day. Others, such as reptiles, thrive in the hot temperatures. Summer nighttime temperatures may themselves be considered hot. It may be

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Temperature (Monthly): The average high and low temperatures, along with the record high and low temperatures, are charted for each month at Fredericksburg and at Llano, Texas. Keep in mind that average temperatures smooth out, and therefore hide, extremes.

90°F well after sunset on a July or August evening, with temperatures drifting down into the lower 80s or upper 70s after midnight, bottoming out in the wee hours overnight. It is rarely cold, but that depends on your definition of cold. Temperatures uncommonly fall to the freezing mark in the winter months. After passage of a cold front, temperatures may drop into the high 20s. Blasts of arctic air a few times a year plunge temperatures into the upper teens for a short time. Hard freezes at least once a year prevent truly tropical plants from thriving in the Llano Region. Normally, temperatures rise above the freezing mark during the daytime, but a strong cold front may keep daytime temperatures below freezing for a day or two. Temperature transitions above and below the freezing mark encourage weathering through the freeze-thaw cycle, breaking granite and other rock types down into their constituent parts. On the other hand, some winter days may seem hot, especially for visitors from

up north. It is possible to hit the 90°F mark in any month of the year, even in the coldest month, January; but most winter days have extremely pleasant daytime temperatures in the 50s to 70s.

Fall Color: The cooler weather in late fall triggers the plants at the park to display some fall color. In addition to the virginia creeper in this photograph, many trees, like the flameleaf sumac, cedar elm, and blackjack oak, show reasonable color, especially if an early freeze occurs in October.

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Precipitation Enchanted Rock SNA is on many days sunny and dry. Sitting not far from the northeastern edge of the Chihuahuan Desert (the Edwards Plateau transitions into the Chihuahuan Desert west of the Pecos River), the park has sunny conditions an average of 65 percent of the time. The percentage of sunshine steadily increases as you travel west through Texas away from the Gulf of Mexico. As you would expect, rainfall across the state shows a similar pattern, quickly tapering off to the west. West Texas receives less than one-quarter of the rainfall that falls on the coast, which can receive upwards of 50 inches annually. Rainfall at Enchanted Rock SNA and across the Llano Region may be triggered

Sunshine Percentage: The percentage of possible sunshine received increases across Texas from east to west. Enchanted Rock SNA receives an average of 65 percent of its possible sunshine annually.

by a number of causes, including cold fronts, dry lines, upper air disturbances and mid-level troughs, tropical systems, and outflow boundaries. Nearby Fredericksburg receives an average of 31.7 inches of precipitation a year— hardly a desert. That is more rain than most of the Central Midwest receives. For comparison, St. Paul, Minnesota, receives only 29.4 inches a year, but the plant life around the Twin Cities could not be more different from that found at Enchanted Rock SNA. Since the two locations receive essentially the same rainfall per year, the differences must be caused by other factors, like maximum and minimum temperature, frequency of rainfall, and other conditions. It is interesting to compare the temperatures and precipitation at Fredericksburg, Texas, with Llano, Texas. The cities are only 40 miles apart. Llano, which sits at the center of the Llano Region, receives on average only 27.3 inches of rain, nearly 4 inches less per year than Fredericksburg. Temperatures are also more extreme at Llano than at Fredericksburg. The difference is primarily a result of the lower elevations within the Llano Basin; Fredericksburg is almost 700 feet higher than Llano. The monthly precipitation chart shows two wet seasons. The bulk of the rain arrives from late March through June as cold fronts, the dry line, and the jet stream all bring strong storms to the area. Another wet season occurs in the fall as cold fronts once again pass through. Irregular tropical systems, including storms that move onshore from the Gulf of Mexico or moisture from storms in the eastern Pacific Ocean, help lift fall rainfall averages. Wintertime whistory eat her

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Precipitation and Evaporation: Precipitation gradually tapers off from east to west across Texas, indicated here by changes in color. Lines and red labels indicate annual evaporation in increments of 4 inches. Enchanted Rock SNA is still quite wet but suffers from frequent periods of extended drought. Conditions are generally xeric. Notice the finger of higher precipitation extending to Fredericksburg but tapering off toward Llano. Though the cities are separated by only 40 miles, Llano’s average annual rainfall is 4 inches less than Fredericksburg’s.

brings frequent and steady light rain and drizzle, but overall accumulations are low. The immediate result of rainfall at Enchanted Rock SNA is lots of wet granite, full vernal pools, and water flowing down the channels on the flanks of the domes and into the intermittent streams that feed Sandy Creek and Walnut Springs Creek. Large rain events will cause Sandy Creek to fill suddenly. Within a couple of hours, the creek level drops, but it continues to flow for weeks or months. Small creeks within the park flow

during and right after a rainfall, but most stop within days after the rain has ceased. Vernal pools, Sandy Creek, Walnut Springs Creek, and a few other wet areas help bridge the gap between rainfalls by retaining water for plants and animals during the dry spells. Channels stop flowing within days, hours, or even minutes. Within days, or weeks at best, vernal pools dry up. Water may flow between exfoliation sheets for many weeks after a large rainfall. As the park is near the headwaters of Sandy Creek and Walnut Springs Creek, they frequently

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dry up completely, except for short stretches downstream of small springs. Those isolated locations may be the only surface water available in the middle of the summer. In the summertime, intervals of 30 days up to even 60 days or more without any rainfall are not that uncommon. Frequent summer daytime temperatures above 90°F and warm evening temperatures lead to rapid evaporation. The annual evaporation rate around Enchanted Rock SNA has been calculated to be about 40 inches, exceeding the annual rainfall and leading to xeric conditions. Large gaps between rainfall events create great stress on plants and animals. To survive, plants must either go dormant or somehow retain water. Cacti, yucca, and succulents store water in their leaves. Many plants flower in the spring or fall and dry up by midsummer. Others, including most grasses, defer flowering until late summer

to late fall or into the winter months. Trees in thin grus are stunted, as the soil is unable to hold much moisture. Trees that do survive have sent roots down into fractures in the granite. Some trees, like the Texas buckeye, go dormant in the summer. Many plants react rapidly to rainfall. For example, showy eveningstar and Drummond's rain lily bloom a few days after it rains (if there was a prior period without rain). Rainfall at just the right time in the spring brings a beautiful display of cactus flowers. Many other plants depend on a large rainfall to complete their yearly cycle. Fairy shrimp quickly lay their eggs in grus before the water dries up. The eggs can survive for months in dry grus. When rainfall does arrive, it often comes in buckets, sometimes with more than 3 inches from a single thunderstorm. Large floods are relatively common, occurring every few years somewhere within

Rainfall (Monthly): A chart of average monthly rainfall at Fredericksburg and at Llano, Texas, reveals the two wet seasons in the park area, one from April to June and the other in the early fall. The averages shown on the chart can be deceiving, however, as any month can be the wettest in a given year.

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soil is present, runoff is quite rapid, exacerbating the flash flood risk. Flooding scours the limestone-lined creeks throughout the Edwards Plateau, leading to (geologically) rapid erosion, exposing deeper, older rocks. Snow is an irregular visitor to Enchanted Rock SNA, with trace amounts occurring on average once per year. Sleet and freezing rain are more frequent, on average hitting the area a few times each winter. Any threat of winter precipitation keeps Central Texas residents safely burrowed in their homes.

Humidity and Heat Index Sandy Creek Drought: During an extended drought, Sandy Creek (and Walnut Springs Creek) dry up, except for some short stretches fed by springs.

the Edwards Plateau. Rainfalls greater than 30 inches, when they occur, lead to awesome flooding. Within the Llano Region, the Llano River may fluctuate from a few feet to 20 or 30 feet over the course of a few hours after a heavy rain event in its watershed. The Pedernales River in Pedernales State Park to the east of Fredericksburg has a flood warning system because the river can rise so quickly from heavy rainfall. Besides the destructive effects on people and animals living along streams during floods, flooding has other, longer lasting effects. Stream banks are attacked, the streambed and floodplain are scoured, and large boulders are rearranged with ease by the power of the water. Deposition occurs at other locations, depending on the flow of the water. Sometimes the streambed is relocated. In the Edwards Plateau, where little

Central Texas frequently experiences uncomfortable humidity, especially in the late spring through early fall. A check of the relative humidity, the measurement most familiar to the public, would provide a misleading view of why conditions are so miserable. The relative humidity may be low, but it is still thick outside. The problem is that relative humidity is not a good measure of how humans perceive heat and humidity (in other words, what feels miserable). A better measure is the dew point. The dew point (or dew point temperature) is the temperature at which a parcel of air is saturated, meaning that it can contain no more water vapor. The maximum amount of water vapor that a parcel of air may contain is determined by air temperature and pressure, and it reaches a little above 3 percent at the hottest temperatures near sea level on Earth. Air at a temperature of 86°F (30°C) may coexist with more than three times as much water vapor as air at 50°F (10°C). Condensation occurs when

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the air is saturated, leading to dew (or frost if temperatures are below freezing). Fog may also form under certain circumstances. Dew points in the mid to upper 60s and higher make the air feel humid, and that makes us uncomfortable by preventing sweat from evaporating from our skin. Relative humidity measures the relationship between the air temperature and the dew point. If the relative humidity is 100 percent, the air temperature is equal to the dew point temperature, and the air is saturated with water vapor. High relative humidity levels mean dew, frost, or fog, but they do not necessarily correlate to uncomfortable conditions. Another measurement important in the summertime is the heat index, which, like the relative humidity, is calculated using the air temperature and the dew point to give a measure of what the air temperature feels like. Higher temperatures and humidity drive the heat index upward. Heat indices over 105°F are considered dangerous. A very hot summer day may have a dew point in the mid-60s and an air temperature near 100°F. The relative humidity may be quite low, but the conditions will be quite uncomfortable. At night, the dew

point may be in the low 70s and the air temperature in the mid to upper 70s. To a visitor, that means a hot, somewhat sticky day and a warm, very steamy night. A winter day with drizzle may have high relative humidity, near 100 percent, but conditions may seem pleasant as the dew point is in the 40s or 50s. Dew point temperatures often rise at night and drop during the daytime. The daytime drop often comes from infiltration of dry air as a result of daytime heating or with passage of the dry line. With sunset, moist air from the Gulf of Mexico reasserts itself.

Seasons Summer Summers at Enchanted Rock SNA are hot and humid. Highs typically reach 90°F to 100°F every day. The average high temperature in July is 93°F. Evening summer temperatures remain in the upper 80s to low 90s well after sunset. At 10 pm, the temperature often stubbornly remains well into the upper 80s. Low temperatures in the upper 60s to upper 70s occur toward sunrise.

Interaction of Heat and Humidity at Enchanted Rock SNA Typical conditions and how they are perceived by humans

Air Temperature

Winter evening, cold night to follow

Winter evening, humid

Winter day, Summer cool and evening, pleasant sticky

Fall day, warm but pleasant

Summer day, steamy and dangerous heat index

Fall day, hot but pleasant away from midday sun

Summer day, hot dry air

30°F

30°F

50°F

80°F

80°F

95°F

95°F

100°F

Dew Point Temperature 18°F

29°F

29°F

76°F

50°F

75°F

45°F

62°F

Relative Humidity

61%

96%

44%

88%

35%

52%

18%

29%

Heat Index

N/A

N/A

N/A

85°F

80°F

107°F

91°F

102°F

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During the summer, Enchanted Rock SNA may have unbearable, near-tropical humidity, or near-desert humidity levels, depending on what air mass is in place over the park. When a Gulf of Mexico air mass is in place, dew points are in the 60s or 70s. If dry desert air dominates, dew points may be in the 30s to 50s. A higher dew point means more steamy conditions. It also means that temperature changes will be slower coming. With higher dew points, daytime temperatures are moderated (reaching only the upper 80s or low 90s), and nighttime temperatures remain in the mid to upper 70s. Lower dew points mean less steamy conditions and a heat index closer to the air temperature. Daytime temperatures may exceed 100°F, but then drop down into the upper 60s at night. High humidity levels give blue skies a milky white appearance. Physical exertion is difficult from 10 am through sunset, with the combination of high temperatures and dew points driving the heat index over 100°F. After midnight, air temperatures drop to near the rising dew point, often triggering low clouds or fog to form from the early morning until the sun burns them off. Cloudy mornings give some respite from the heat, keeping temperatures from rising too rapidly for a little while. Forget about summer relief from cold fronts with their associated rain and cooler temperatures. In most years the summer pattern becomes entrenched starting in mid-June, with average rainfall tapering off quite rapidly, and remains in place until mid to late September, when another wet spell begins. Stalled upper air disturbances, however, with associated rainfall, can bring

summer relief. An unusual rainy summer day keeps the highs down into the middle 80s. Once the rain stops, though, conditions resemble a steamy Houston bayou. A squeegee may be required to keep the sweat off your body. The temperatures will quickly climb back into the 90s if the sun comes out. Temperatures fluctuate the least in the summertime, with little variation from one day's high or low temperature to the next.

Fall Arrival of the first strong cold front sometime from mid-September to early October brings welcome, if at first slight, relief from the brutal summer. Thunderstorms, higher winds, lower dew points, and cooler temperatures arrive. Finally, high temperatures only make it into the 80s or lower 90s, followed by nighttime lows in the 50s or 60s. Some days remain very summerlike, with hot, stifling, humid air. Others are downright pleasant. You may even need a sleeping bag if you are camping. Fall may bring occasional tropical systems from the Gulf of Mexico or the Pacific Ocean. Remnants of tropical systems affect Enchanted Rock SNA once or twice a decade. The greatest effects on the park from Gulf storms are due to rain bands, which bring very heavy rains until the storm disintegrates or moves out of the area. Another possible source of moisture is tropical storms originating in the Pacific Ocean to the west of the Baja Peninsula. Although the Sierra Madres strip out lowlevel moisture, an arc of mid- and upperlevel moisture may make it into Texas,

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Moon over Boundary Rocks: The clear skies, relatively dry air, and remoteness from large cities make for good conditions to view the stars and other astronomical objects. Bring your binoculars, telescope, or just a lawn chair to enjoy the dark skies.

bringing widespread heavy rainfall for days at a time. By November or December, daytime highs are very pleasant, and the evening temperatures are great for cool-weather camping. Tropical storms are no longer a threat. Lower humidity levels bring beautiful blue skies and excellent star watching conditions. Finally, the nights are cool enough for a roaring campfire at the park, and you don't have to hide from the sun in the daytime. Late fall can bring a condition known as overrunning, when the subtropical jet stream carries warm, moist air into Texas. If a cold front has passed through the area, cold dry air establishes itself at the surface.

Warm air from the Gulf of Mexico or the Pacific Ocean rides over the top of the cold air in place at the surface, triggering dreary Seattle-like weather, with cool temperatures and light rains or drizzle. Under these conditions, the rainfall is usually not heavy, but it stubbornly continues for days at a time.

Winter The winter season at Enchanted Rock SNA should be renamed to something like "cool fall." It is rarely cold during wintertime, unless you are comparing it with the weather in the Rio Grande Valley. The average daytime temperatures are pleasant,

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Winter at Enchanted Rock: Sleet and snow cover Enchanted Rock Dome in the distance, with Little Rock Dome in the foreground. At least a trace amount of frozen precipitation falls on the park roughly once a year. It presents a lovely sight, but only for the lucky few who are already at the park before it begins, as winter precipitation usually melts in less than a few hours.

with highs in the 50s through 70s. Evening temperatures typically drop down into the 30s or 40s. November, December, January, and February are the only months that have not seen 100°F temperatures. All months have seen temperatures in the 90s. Highs at or above 80°F are easily achievable any winter month. If visiting in the winter, pack your shorts, T-shirts, sunglasses, and large water bottles, along with your raingear, winter jacket, gloves, sweatshirt, and warm hat. That should cover the possible weather conditions. Strong cold fronts that pass through the area in the winter are known as blue northers. Only the passage of a blue norther creates what could be considered proper winter conditions. The most likely

precipitation in this case is freezing rain or sleet, but snow may also fall, rarely. If you are hoping to see snow at Enchanted Rock SNA, you may have a long wait. Accumulation in any amount occurs on average once per year. Snow seldom lasts beyond the first few hours of sunshine after a nighttime snowfall. Many ambitious forecasts of snow are dashed as an advancing arctic air mass encounters Gulf air. More likely is a line of rain showers and thunderstorms associated with a front. Similar to the late fall, overrunning may lead to days of drizzle as warm air from the Gulf flows over the cold air at the ground. Sunshine and cool, pleasant temperatures return once the overrunning condition breaks down.

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Spring

Air Masses and the Jet Stream

Most early spring days are pleasant, with highs in the 70s or 80s. Evenings are cool, with lows in the 30s through 50s. As the spring season progresses, the temperatures steadily increase, until highs are in the upper 80s or 90s and lows in the 60s or even 70s. Rainfall is greatest in the late spring, as the subtropical jet stream spins off upper air disturbances, surface lows and associated cold fronts, and the dry line on occasion passes through the area. Individual thunderstorms may produce more than 3 inches of rainfall. Hail or high winds associated with a storm can wreak havoc on campers. On the other hand, if the summer pattern establishes itself early, the intervals between rainfalls may be measured in weeks. The frequent and heavy rains trigger an explosion of plant growth. By mid to late March, dry weathering pits turn into vernal pools, supporting rock quillwort, sedum, fairy shrimp, and other plants and animals. Wildflowers bloom throughout the park. Butterflies and birds proliferate and take advantage of the flowers and plant growth. By late spring, the subtropical jet stream has migrated north of Central Texas, and warm, humid Gulf air settles in, setting up conditions for a long, hot summer. Temperatures begin to get quite summerlike by mid-May. There are increasingly shorter periods of relatively cooler temperatures until mid-June, when the summer pattern typically firmly establishes itself.

What makes the weather do what it does over Central Texas? Proximity to the Gulf of Mexico, the Chihuahuan Desert, the center of the North American continent, and even the Pacific Ocean all influence the weather. The park’s fairly southern location, around 30° north latitude, is also quite important. Three air masses have the largest influence on the weather in Central Texas: maritime tropical, continental tropical, and continental polar. Continental arctic air sits over the North Pole but penetrates into Central Texas once or twice each winter, bringing the coldest temperatures of the year. Maritime polar air infrequently makes its way to the area, but the air mass is typically stripped of its moisture by the Rocky Mountains. These air masses are not static entities; they are dynamic, changing bodies that ebb and flow over the continent. The time of year has a high correlation to the size and location of the various air masses. Collision between the air masses is one of the main causes of precipitation and stormy weather. The most dominant air masses over Central Texas are maritime tropical, one originating over the warm waters of the Gulf of Mexico and extending eastward into the Atlantic Ocean, the other over the Pacific Ocean west of Mexico. Both are warm and moist, and their presence brings ample precipitation, flood events, and high humidity that affect Central Texas. The continental tropical air mass consists of warm to hot and dry air from the deserts of the southwestern United States.

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Air Masses: Large air masses greatly affect the weather at Enchanted Rock SNA. They ebb and flow across the continent, and their influence changes with the seasons. The Bermuda high typically drives moist maritime tropical air into the central United States, but a blocking ridge of high pressure (not shown) over Central Texas keeps rainfall away throughout the summer months. From fall through spring, occasional cold fronts bring cold and dry continental air to the area, along with precipitation as the fronts pass. In the springtime, dry lines work their way east across Texas, bringing hot, dry continental tropical air and occasional severe storms.

It plays a large role in Texas weather in the spring through fall. Infiltration of this air into the region brings lower dew points but higher temperatures and possibly drought conditions, if it remains in place for an extended period of time. The continental polar air mass is cold, dense, stable (it tends to settle, not rise) continental air that carries little moisture. It is often associated with high-pressure systems, and its encroachment into Central Texas often corresponds to cool or cold temperatures, lower dew points, and winter precipitation events. The rotation of the earth, along with differential solar heating at the equator compared with the poles, creates global-scale circulation in the atmosphere. Hadley, Ferrel, and Polar cells equalize temperatures across the globe.

High-speed rivers of air known as jet streams run at the boundaries of the cells. The subtropical jet stream runs at the boundary between the Hadley and Ferrel cells, and the polar jet stream runs at the boundary between the Ferrel and Polar cells. South of the subtropical jet stream is maritime or continental tropical air; north of it is continental polar air. The polar jet stream separates polar from arctic air. It typically remains well to the north of Central Texas, but its presence in Central Texas corresponds to the presence of bitter arctic air. A jet stream pattern relatively flat from west to east (zonal flow) brings fewer storms. A jet stream pattern with more curves brings increased changes and storms, as air masses are thrust into one another. A ridge of high pressure is present east of where the jet stream curves

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Circulation Cells: Hadley, Ferrel, and Polar cells are global rotational units in the earth’s atmosphere. They form as a result of the rotation of the earth and through differential heating of the atmosphere from the tropics to the arctic. Jet streams run between the cells. General precipitation and surface winds for a given latitude result from the location of the cells and the jet streams. The subtropical jet stream, typically flowing over Texas in late fall through early spring, is one mechanism for triggering rainfall in Central Texas.

northward. A trough of low pressure occurs west of where the jet stream cuts southward. The boundary between circulation cells drifts north and south with the seasons. In the summertime, the subtropical and polar jet streams are usually far north of Enchanted Rock SNA in the Great Plains and Canada, respectively, locking maritime or continental tropical air into Central Texas. In late fall through early spring, the subtropical jet stream frequently extends out from the Gulf of California, across Mexico, and continues across Central or North Texas bringing rapidly changing weather and increased precipitation chances. Smaller-scale clockwise and counterclockwise twists at various levels of the atmosphere also form. Clockwise twists at the surface, known as high-pressure systems in the northern hemisphere, are places where air piles up and sinks, leading

to higher pressures and a generally less stormy pattern. In counterclockwise twists, known as low-pressure systems, air rises up and out, leading to lower pressures and a generally increased chance of storms. Eddies, currents, and kinks higher up in the jet stream lead to the generation of upper air disturbances, which are lowpressure areas 20,000–30,000 feet up in the atmosphere. They often contribute to the development of high- and low-pressure features on the surface.

Air Stability and Clouds Abstract units of air known as air parcels are said to be in equilibrium when they are the same temperature as surrounding air parcels. Air parcels that become warmer than surrounding air parcels are not in equilibrium; they tend to rise. whistory eat her

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Stable and Unstable Air: In stable air (shown on the left), rising air parcels are or quickly become cooler than the surrounding air parcels, and they sink back down. Clouds form if air cools to the condensation level. Note how the air parcels cool at a slower rate above the condensation level. In the situation on the right, the air parcels are stable below 4,000 meters, but above that altitude, conditions become unstable as rising air parcels encounter a layer of cooler air and, as a result, tend to keep rising.

Lifting processes, such as variations in the landscape (orthographic variations), heating by sunshine, or wedging of one air mass by another, can cause air parcels to rise. Rising air parcels experience reduced pressure, with a corresponding expansion and adiabatic cooling of the air parcel. Once the temperature of the rising air matches the temperature of the air at a given altitude, the rising air reaches equilibrium and stops rising. A stable air mass is one in which air parcels tend to sink or reach thermal equilibrium quickly. In an unstable air mass, air parcels tend to rise quite a bit before equilibrium is reached. If in the course of rising, air parcels reach the dew point or condensation level, clouds form. The cloud types that form depend on the air masses present, the stability

or instability of the air, and the dew point and air temperatures. Layers of clouds may form at different altitudes. Air parcels can continue to rise after reaching the dew point temperature, but the cooling (lapse) rate is lower.1 One type of cloud, the fair-weather cumulus (those white clouds that look like cotton), forms as rising parcels of air are heated by sunshine, leading to expansion and cooling until the dew point is reached and the clouds form. On most days, the cloud growth is checked as a warmer layer of air is reached. Sunset removes the warming effect on the ground, and the clouds quickly dissipate. Boundaries between air masses, or fronts, introduce instability if one air mass is pushed under or over another one. The various types of clouds formed as a result are too numerous to list here.

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Bermuda High and Sea Breeze During summertime, extensive sunshine over the subtropical Atlantic Ocean creates a temperature differential between the subtropics and the midlatitudes. Large-scale circulations such as the Hadley, Ferrel, and Polar cells help reduce the differential (that is, they attempt to restore thermal equilibrium) by circulating warm air away from the tropics. Nearer the surface is the Bermuda high, a clockwise flow of maritime tropical air over the Gulf of Mexico that extends out into the Atlantic Ocean.2 Clockwise rotation around the Bermuda high drives moist, humid air from the Gulf of Mexico into Central Texas and up into the Midwest. The steady low- and midlevel flow is the primary source of precipitation in North America during the spring and summer. Without the Bermuda high, North America might resemble the dry savannas of eastern Africa. In a typical summer, by mid-June the Bermuda high establishes itself across the Gulf of Mexico, lasting until midSeptember. The Texas coast sees an influx of low- and mid-level maritime tropical air, which finds its way into Central Texas and develops into a ridge of moist but sinking air, suppressing the influence of the other air masses in Central Texas. The so-called summer pattern develops, with hot and humid conditions but little rainfall. Near the Texas coast, onshore flow of low-level moist air is forced upward as it moves over the coast, creating what is known as the sea breeze. Thunderstorms often form at the coast from the rising

moist, warm air. These storms are pushed west as the day progresses. Unfortunately for Enchanted Rock SNA, the storms typically dissipate as they approach Austin and the corridor of Interstate Highway 35, well to the east of the park. Nightfall removes the solar energy source for sea-breeze storms, and they quickly fade away. If you check out the weather radar in midsummer, you may notice how rainfall seems to spin clockwise around the borders of Texas, with Enchanted Rock SNA roughly at the center of circulation. To the west, rain associated with the monsoonal flow stays in far West Texas and New Mexico. Rainfall from fronts rarely penetrates farther than North Texas. The sea-breeze storms never make it to the Llano Region. In late fall through early spring, less sunshine on the subtropics weakens the Bermuda high, and its influence retreats across the Atlantic Ocean (where it is then referred to as the Azores high). As its impact ebbs in Central Texas, the summer pattern breaks down. Gulf air continues to find its way into Central Texas, playing an important role in triggering large rain events, but it no longer piles up into the blocking ridge that keeps other air masses out. More reliable rainfall returns as air masses once again clash over Central Texas.

Surface Lows and Highs, Cold Fronts, Warm Fronts Counterclockwise eddies form along the jet stream, leading to the development of surface low-pressure systems (surface lows). As the surface low winds up, it pulls air in,

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up, and out of the low-pressure area, reducing the pressure. On the leading east edge of the surface low, maritime tropical air is pulled in from the south and east. From the north and west comes continental polar (or arctic) air. Continental tropical air can also be pulled into the surface low from the southwest. The stronger the surface low, the stronger the wind. The direction to the center of a low-pressure system relative to your location can be determined by the wind direction. A strong surface high can also accentuate the pressure gradient and therefore the wind. The influx of air masses into a surface low creates boundaries between the air masses, known as fronts. The boundary between in-place continental polar air and incoming warm air is known as a warm front; it is shown on surface maps as a

curved line with red half-circles. After a warm front passes through an area, temperatures and humidity levels generally rise. Advancing tropical air, typically from the Gulf of Mexico, rides over the top of denser polar air, causing the warm front at higher altitudes to be much in advance of the front at ground level, sometimes by hundreds of miles. A slowly thickening cloud deck (with a sequence of different cloud types) is often indicative of an approaching warm front. Warm fronts are more common in the center of the United States than they are in Central Texas, but they do occasionally play a role in the late winter through early spring. The lowering cloud deck frequently leads to drizzle or widespread rain as the front approaches. The boundary between an approaching continental polar (or arctic) air mass and

Fronts and Dry Line: In this surface map from a spring day, two low-pressure systems help accentuate the boundaries between the in-place continental polar air (cP), the maritime tropical air (mT), and the continental tropical air (cT). The front is stationary over Kansas. A warm front drives up through Illinois and other midwestern states. Through New Mexico and the Panhandle of Texas is a cold front. And a dry line approaches Central Texas. Precipitation is triggered by the clash of air masses near the fronts. Green indicates rain, white snow, and yellow fog.

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Warm Front Cross Section: A warm front is the boundary between maritime tropical air (mT) and in-place continental polar air (cP). The front, at ground level, trails far behind the air mass boundary at altitude. Warm fronts have thickening cloud decks with different types of clouds overhead as the front approaches. Moderate rain may fall ahead of the passage of the front.

Cold Front Cross Section: A cold front is a wedge of dense continental polar air (cP) or arctic air (cA) that displaces the warm unstable maritime tropical air (mT) up and over the cold air as it advances. As unstable warm air is forced upward, cells of severe thunderstorms may form squall lines, especially if the maritime tropical air is unstable. With stable maritime tropical air (not shown), rain and showers may develop, but the threat of thunderstorms is mitigated.

maritime tropical air is known as a cold front. Its location is represented as a curved line with blue triangles. The vertical profile of a cold front looks very different from a warm front. Cold, dry, but dense air wedges under the warm moist tropical air, creating a sharp contrast at the surface and trailing behind. When the cold front passes, temperatures drop rapidly and humidity levels drop. As noted previously, strong cold fronts in the winter are known as blue northers. A strong cold front that displaces

unstable tropical air leads to the formation of squall lines of thunderstorms ahead of the front. Across the front, where the incoming polar air pushes ahead faster, bow echoes (named after their appearance on radar) act as focal points for the strongest winds and most severe storms. Cold fronts that displace stable tropical air lead to less violent storms near or ahead of the front, and more widespread rainfall after passage of the front. Many pressure lows have both warm

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and cold fronts. Cold fronts traveling faster than warm fronts can catch up to the warm front. The result is an occluded front, with a complex mix of in-place dry polar air, incoming dry and colder polar air, and warm moist tropical air at various levels of the atmosphere. A stationary front may occur when a front is stalled over an area. Such a front is shown with a combination of red half-circles and blue diamonds. Stationary fronts may produce prodigious amounts of rainfall if there is moisture to tap from the Gulf. Some of the heaviest winter rain events in Central Texas involve the presence of a nearby stationary front. As cold fronts move across Texas, ample tropical air nearer its source slows the progress of the cold front. If the front stalls, it becomes a stationary front. If the front reverses in direction, it becomes a warm front. In the summertime, cold fronts typically never make it to Central Texas, but in other seasons, the tropical air mass is not as strong, and the cold front may be able to advance to the coast and beyond. Unless the cold front is quite strong, however, it is modified as it advances, becoming thinner as mixing occurs. Warm tropical air rides over the top of the polar air, leading to a condition known as overrunning. Overrunning creates a layer of stratus clouds with associated drizzle or light rain. If surface temperatures are below freezing, the falling rain freezes on contact with the ground, and freezing rain results. If the cold layer is thicker, falling rain freezes on the way down, leading to sleet. Snow occurs only if the wedge of cold air is deep enough to displace warm tropical air, preventing it from rising over the top of the cold polar air.

The topography across the Edwards Plateau contributes to the modification of cold fronts. The denser polar air hugs the ground, and the lowering elevation to the east and south across Central Texas allows warm air to overrun approaching fronts more easily. As a result, sleet and freezing rain are much more common in Central Texas than snow.

Dry Line The continental tropical air mass is created as air from the Pacific Ocean passes over the Rocky Mountains in northern Mexico and the southwestern United States, stripping the moisture out. The resulting dry air descends the eastern slopes of the Rocky Mountains. Dew points within a continental tropical air mass may be as much as 50°F lower than those within a maritime tropical. Dry continental air is more easily heated than moisture-laden maritime air, so the same amount of sunshine applied to a continental and to a maritime air mass will heat the continental air more than the maritime air. Temperatures at the Texas coast are moderated lower during the summer compared with those found in West Texas (but higher elevations help to keep temperatures down in many West Texas locations). Differential daytime heating and subsequent expansion help drive a continental tropical air mass into a maritime tropical air mass. The boundary between the two air masses, which sharpens as the day progresses, is known as the dry line (or dew point front). The dry line is shown on surface maps as a dashed line with half-circles. To the west of the dry line is hot, dry

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Dry Line Cross Section: With a strong flow of moisture from the Gulf of Mexico, a wedge of warm, humid maritime tropical air (mT) extends across Texas, getting thinner toward the west. With daytime heating and a strong flow of dry continental tropical air (cT) from the west at the mid-levels, mixing of the moist air with the much larger dry air mass advances the dry line to the east as the day progresses. A capping inversion typically resides above the warm moist mT air, checking the development of thunderstorms. If the cap is breached, watch out for large thunderstorms, possibly with tornadoes.

continental air, and to the east is warm, moist maritime air. It will be quite obvious which side of the dry line you are on. Maritime tropical air is humid and murky, with visibility limited to 10–20 miles. Low morning clouds in the maritime air mass burn off by midmorning. Continental air is dry and hot, with beautiful blue skies (assuming no other weather effects are influencing the situation) and visibility of 20, 40, even 60 miles. The two air masses mix at the boundary, where the maritime air dries out and incorporates into the continental air mass. As maritime air dries out, the dry line pushes to the east, sometimes initially moving quite rapidly through the thinner layer of maritime tropical air present in Central Texas or the western Great Plains.3 As the dry line progresses east, it encounters thicker maritime air and progress slows. Warm, moist maritime air is denser than continental air. As the dry line pushes east, the hot dry continental air overrides

the warm moist maritime air mass (or the maritime air wedges under the expanding continental air mass). The mixing zone of continental and maritime tropical air at a few thousand feet above ground level may be well east of the mixing zone at the surface, where the dry line is located. Within the maritime tropical air mass, adiabatic cooling leads to formation of scattered, ragged cumulus clouds. Mixing with the continental air mass overhead dries out the air, the promising cumulus clouds dissipate, and the dry line progresses to the east. Extension of the continental air mass over the top of the maritime air mass leads to a condition known as the capping inversion (or just “the cap”). Sunshine on the ground where the maritime air mass is present leads to rising parcels of air, adiabatic cooling, and formation of ragged cumulus clouds. With higher temperatures above the cap, rising parcels of maritime air reach equilibrium before they are mixed whistory eat her

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with expanding continental air. Once mixed, the clouds dissipate and the dry line advances. When the cap is thin and ample sunshine and unstable maritime air is present, rising maritime air can breach the cap, especially later in the afternoon. Explosive growth of large thunderstorms can occur as the maritime air parcels rise unchecked. Sometimes the resulting storms can rise to 50,000 feet in a matter of 10 minutes. Surface winds, especially if associated with a nearby cold front, may contribute to the development of bulges along the dry line, which serve as a focal point of uplift energy, leading to some of the most severe storms that form across the central United States. Ironically, stronger onshore flow of maritime air from an upper air disturbance, low-pressure system, or other feature may help prevent the cap from forming, leading to widespread heavy rainfall but no severe thunderstorm development. Supercells are compact thunderstorm complexes with hail and tornadoes that may last for many hours. They require that key ingredients be in place, including the presence of a nearby dry line. The dry line rarely reaches the coast. In the early springtime, it often reaches a point somewhere near or east of Austin before it stalls. Once daytime heating has subsided after sunset, the continental air mass cools more quickly than the maritime air mass, mixing subsides, and the dry line migrates to the west as the maritime air dominates. As the continental air mass retreats, storm formation moves to the west, too. Once the sharpness of the boundary

between the continental and maritime air masses is reduced, thunderstorms dissipate until the next day. By summertime, the Bermuda high and its associated high-pressure ridge are strong enough to keep the dry line well to the west or north of Enchanted Rock SNA. The dry line thunderstorm action moves northward across the United States throughout the summer and does not return to the Central Texas area until fall.

Upper-Level Disturbances Weather phenomena at the upper levels (and mid-levels) of the atmosphere make a critical contribution to rainfall received in Central Texas. The proximity of the Gulf of Mexico, in conjunction with these phenomena, can lead to very heavy rainfall for days at a time. In some events, the rainfall amount may be comparable to that brought in by hurricanes; some of them are among the most impressive rainfall events in the United States. An upper air disturbance is just a counterclockwise eddy spinning off of the subtropical jet stream at 20,000–35,000 feet. Such eddies often form over New Mexico or the Panhandle of Texas and then track east and north. Additionally, troughs and ridges can develop not only at the surface but also at the mid and upper levels of the troposphere, where they can be referred to as a mid-level trough or mid-level ridge. They are not shown on surface maps, but meteorologists track them quite closely. When upper air disturbances are in certain locations, such as the Texas Panhandle or along the Rio Grande, they may pull

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huge amounts of warm, moist, unstable, and, most important, deep maritime tropical air from the Gulf of Mexico into Central Texas. Widespread thunderstorms will result. A mid-level trough located to the west of Central Texas can have a similar effect, pulling Gulf moisture and, subsequently, thunderstorms into Central Texas. If this deep moisture is pulled inland over the Balcones Escarpment and west across the Edwards Plateau, the topography can lead to extremely heavy rainfall; some of these events approach the limits of rainfall intensity. A series of back-to-back upper air disturbances or a stalled upper air disturbance can lead to days of tropical rainfall as impressive as any hurricane can produce. Some of the largest flooding events in Central Texas history are associated with a series of upper air disturbances interacting with a stationary front in just the right place, helping to concentrate rainfall over the same area again and again.

Tropical Systems Enchanted Rock SNA is too far inland to see the direct effects of a tropical system, such as storm surge or hurricane-force winds. Only every few years or so does Central Texas see large rainfall events from the remnants of tropical storms or hurricanes. Tropical systems approach Central Texas from two general sources, the Gulf of Mexico and the Pacific Ocean. When one does, its rain bands can deliver widespread rain; it is not unheard of to get rainfalls of more than 30 inches in small areas. On

the other hand, a hurricane tracking into East Texas may bring a beautiful, peaceful sunny day to Enchanted Rock SNA. Such was the case with the powerful Hurricane Rita in 2005. Pacific Ocean tropical systems approaching western Mexico or the Baja Peninsula can also affect Central Texas. The storm itself may or may not make it to Texas, but moisture from the storm can get caught up in the subtropical jet stream and carried into Central Texas, where it can bring ample rainfall across the area. Flooding from tropical systems is a major factor in the mass removal of material from the Edwards Plateau, leading to the continued relatively rapid erosion of the plateau.

Outflow Boundaries The final mechanism that triggers rainfall across Central Texas is known as an outflow boundary. Thunderstorms have miniature circulation systems that have inflow and updraft, bringing air into the developing cell and pushing it to high altitudes. The air is then pushed out, down, and away from the cell, creating a pressure wave that travels down and away from the storm. The effect is noticeable when a cool, strong wind suddenly picks up just before the thunderstorm cell arrives. These winds are known as straight-line winds; if they are strong enough, they may produce as much damage as a small tornado, but with a different pattern since there is no rotation. The pressure wave may travel outward dozens of miles from a thunderstorm cell, sometimes 100 miles or more. The outflow

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boundary itself is often strong enough to trigger the formation of further thunderstorms well away from the original thunderstorm. A collapsing thunderstorm may produce a similar effect, when the updraft within the cell fails and air rushes outward, away from the cell.

El Niño, La Niña, and the Southern Oscillation All of the previously described weather phenomena are short-lived and operate on medium to small scales on the earth. El Niño and La Niña, however, are part of a global weather pattern associated with the Southern Oscillation. The Southern Oscillation involves a change in ocean surface temperatures, along with a shifting of air masses from the eastern Pacific Ocean to the western Pacific Ocean over a period of a few years, influencing the path and intensity of storms from the Indian Ocean to North America. During El Niño years, the westwardblowing trade winds weaken across the Pacific Ocean, and a large body of warm water makes its way to the west coast of South America. The warm water greatly influences the weather across North America. The intensity of storms increases on the west coast of the United States, extending across the southern United States into Texas, as maritime tropical air from the Pacific Ocean finds its way more frequently into Central Texas, often via the subtropical jet stream. Many of the wettest years and most catastrophic flood events in history can be correlated to El Niño years. In the opposite condition, known as La

Niña, the waters off the west coast of South America are cool, and drought conditions often prevail across Central Texas. Lower dew points can lead to higher summer temperatures, as the continental tropical air mass becomes dominant. Winter temperatures may also be warmer. In years that are neither El Niño nor La Niña, conditions appear to be more favorable for hurricane formation in the Gulf of Mexico, as was the case in 2005 when the National Weather Service ran out of hurricane names. That was the year that Hurricane Katrina devastated New Orleans, Hurricane Rita ravaged East Texas, and there was a hurricane at the end of December. El Niño and La Niña patterns both tend to last for a couple of years before breaking down. During the transition between the two conditions, the weather is more normal in Central Texas, with moderate temperatures and precipitation near the long-term normals for the area.

Historical and Extreme Weather We don’t have to look far back to find extreme weather years in Central Texas. The years 2006 and 2007 are great examples of the wide range of conditions that can be encountered. Indeed, these two years demonstrate how apparently normal years, according to statistical records, can in reality be quite extreme. In 2006, a multiyear drought was affecting much of Texas, Central Texas being no exception. Rainfall that year in Fredericksburg and Llano was 24.88 and 21.32 inches, respectively. The annual rainfall, however,

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does not indicate the stress caused by extended periods without rain. The spring, summer, and fall seasons all saw weeks on end without any precipitation. The surface flow of Sandy Creek through Enchanted Rock SNA was absent. The only surface water sources within the park were at Moss Lake, Frog Pond, and a couple of small spring-fed areas along Sandy Creek, the spring along Walnut Springs Creek, and a small pool of water along North Walnut Springs Creek. Fish, frogs, dragonflies, and other water-dependent creatures were heavily concentrated in very small pools of water. As pools dried up, only fish bones remained. The isolated springs in Sandy Creek saw amazing numbers of frogs concentrated around the water sources. Not a turtle or toad was seen by the author the entire year. Many trees died, and plants remained dormant until sporadic rainfall triggered their blooming, somewhat out of their normal seasons. The year 2007 started out completely differently. The La Niña conditions appeared to be breaking down. An active jet stream pattern and multiple upper air disturbances during the springtime brought regular and ample rainfall throughout. Then, in the late spring and early summer, an unusually relentless series of stalled upper air disturbances brought huge amounts of rainfall over much of Texas, Oklahoma, and Kansas, including more than 19 inches at Marble Falls in 24 hours. Lake Travis, the flood-control lake on the Lower Colorado River near Austin, went from 660 feet to 700 feet in a matter of days. Sandy Creek and Walnut Springs Creek filled their banks numerous times, much to the

distress of the park staff, who continually had to rebuild trails and unclog the vehicular bridge over Sandy Creek. Remnants of Tropical Storm Erin brought another round of heavy rain, measured in feet in some Central Texas locations. By late summer, the drought over all of Texas was declared over. The effect on plants and animals was significant. A most amazing burst of wildflowers continued from early spring through the summer. In early August, the park was still quite verdant, and flowers typically associated with the springtime were still to be found. Sandy Creek and Walnut Springs Creek continued to flow throughout, along with numerous minor waterways. Even Campside Creek filled its banks several times and would have been dangerous to cross on those occasions. Waterfalls appeared at numerous locations in Enchanted Rock SNA during heavy rainfall events. High temperatures remained in the 80s for most of the summer, thanks to the increased cloud cover, rainfall, and moisture content in the ground and air. Then in September, La Niña reasserted itself and drought conditions slowly returned. By the end of 2007, the park was very dry, and Frog Pond completely dried up, something that had not happened in 2006. Even with the drought conditions at the beginning and end of the year, Fredericksburg received 50.66 inches and Llano 34.74 inches of rainfall. The drought continued into 2008, when this book went to the publisher. Similar climatic events have occurred in the past, when multiyear droughts brought ruin to farmers and ranchers, and

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Sandy Creek Flood: Sandy Creek fills its banks after a very heavy rainfall in 2006, making the bridge crossing in the park impassable.

Waterfall on Enchanted Rock: Heavy rains bring a waterfall to the south side of Enchanted Rock Dome (visible at left). Campside Creek, at the bottom of the image, is flowing fast enough to be dangerous.

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droughts were frequently broken by the other extreme of heavy rainfall leading to extensive flooding downstream of the park along the Pedernales, Llano, and Lower Colorado rivers. The drought ending in 2007 was nothing compared with the one that occurred during the early and middle 1950s, which affected much of Texas. Other serious multiyear droughts have occurred before that. Many periods of drought seem to end with a flood year. In an area subject to weather extremes, like Central Texas, the monthly precipitation chart is not a good indicator of the variation in annual rainfall. Any month can be completely dry and any month can be the wettest for a given year. A look at the annual rainfall over a number of years gives a better indication of the variability. The drought of 1951–1956, which affected all of Texas, produced only 12 inches of rainfall at Llano in 1954 and 1956. The years 1908–1911 were similarly dry, averaging only 11 inches of rainfall. At the other extreme, 1919 brought roughly 50 inches of rainfall. Even a year with average or above-average precipitation may see stress from drought, depending on the timing of rainfall. The world record for rainfall in an 18hour period was set in 1921 at Thrall, Texas, just north of Austin, when 36.4 inches of rain fell as a result of a hurricane remnant. In 1954, heavy rainfall caused the discharge from the lower Pecos River (sometimes completely dry in the summer months) into the Rio Grande to exceed the flow at the mouth of the Mississippi River. In August 1978, the remnants of Tropical Storm Amelia dumped more than 48 inches of

rainfall near Medina, Texas, in three days, a U.S. record. During that storm, the Guadalupe River went over the top of the U.S. Highway 281 bridge, which stands 53 feet above the river bed. Probably the largest and most destructive flood occurred in 1869, when heavy, widespread rainfall over the Lower Colorado River watershed led to destructive flooding of Austin and many other locations across the Texas Hill Country. Another rainfall event in Medina County near D’Hanis, on May 31, 1935, released more than 22 inches of rainfall in 2 hours 45 minutes, another world record for the time period. Dams at the same location in Austin failed repeatedly—in 1900, 1915, and 1935—before the latest dam was built in 1938 and the dam forming Lake Travis was built in 1937–1941 to protect Austin from regular flooding of the Lower Colorado River. In December 1991, heavy rainfall in the Lower Colorado River watershed caused Lake Travis to rise to a height of 710 feet, 4 feet below the spillways. That particular event was preceded by a wet year, and although the rainfall was widespread and heavy, it was not epic. Unlike the seemingly regular flooding across the Edwards Plateau, large snowfalls are not at all common, but they have occurred in the past. A snowstorm on January 12, 1985, produced as much as 13 inches of snow a couple of counties southeast of Llano County, with around 8 inches of snow around Enchanted Rock SNA. Longer-term climatic changes are also occurring. Certainly the area has been drying out since the peak of the most recent glacial period, about 20,000 years ago,

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Annual Rainfall at Llano, Texas (1900–2007): Plotting the area’s rain over more than 100 years highlights the extremes of rainfall and their seemingly cyclical nature. The extreme drought around the 1910s had less annual precipitation than even the devastating drought period in the 1950s.

Selected Historic Floods Along Balcones Escarpment: Even though the map plots only a subset of the flood events over the past 100 years, Central Texas is plastered with the footprints of numerous large floods. Each flood event is shown in a different color scheme, with dates and rainfall totals.

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when ice reached down from the North Pole as far south as Iowa. Central Texas temperatures would have been much cooler and precipitation higher then. As the climate warmed and dried out, the range of many plants was reduced, sometimes retreating north, south, or some other direction. In other cases, some plant species became stranded in little islands where microclimates still supported them. One example at Enchanted Rock SNA is the hammock fern, which is isolated from its home range in the mountains of northern Mexico. Looking to the future, it is not clear what effect global warming may have on small areas such as the Llano Region. Will there be warmer temperatures? Higher precipitation? Increased cloudiness? Weather at Enchanted Rock SNA allows

it to support animals at the extremes of their range. Eastern rainfall rates, fronts, coastal and tropical warmth and humidity, plentiful rainfall, and long periods of desertlike dryness bring together plants and animals that survive together in interesting juxtaposition.

Notes

1. The dry lapse rate, which applies when air parcels are warmer than the dew point temperature, is higher than the wet lapse rate, which applies once air parcels reach the dew point. 2. Another smaller-scale phenomenon that helps to reduce the temperature differential between the subtropics and midlatitudes is the hurricane. 3. Toward the west, the maritime tropical air mass gets thinner as the Edwards Plateau rises higher above sea level.

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Fairy Swords on Granite Flanks: This small clump of fairy swords exemplifies the sometimes tenuous hold plantlife has on the granite. The boulders behind the ferns slow down the flow of water, extending to days the time it flows. A small collection of grus has been trapped by the weathered boulder next to the ferns. The ferns survive dry spells by going dormant, only to green up when rain returns.

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Flora and Fauna

s

The Llano Region supports an interesting juxtaposition of plants and wildlife associated with a wide variety of environments, such as forests, deserts, plains, and the tropics. The subtropics are not far to the south; the Chihuahuan Desert is relatively close to the west; the Great Plains, running through the middle of the United States, terminate at the Edwards Plateau; and the deciduous forests of the eastern United States fade out just to the northeast. As long-term climate change made Central Texas hotter and drier over the last 10,000 years, remnant populations of some plant species in Central Texas became isolated away from their subtropical, forest, or High Plains ranges. This has left Central Texas with a great diversity of plants and animals. In all, some 2,300 species of plants can be found across the Edwards Plateau. Many species are endemic to the Edwards Plateau, with a subset endemic to the Llano Region. Granite-derived soil is acidic, unlike the highly alkaline soil produced by limestone, supporting plants within the Llano Region that do not thrive outside it. Central Texas is positioned along a major flyway for birds traveling south to their wintering grounds and returning north in

the spring. It also serves as the wintering grounds for many bird species. Monarch butterflies migrate through the area in the fall on their way to overwinter in Mexico. Other isolated populations of subtropical butterflies in some years stray northward during the summer months. Because of the great diversity of plants and animals across the Edwards Plateau and Llano Region, it is quite challenging to create a guide to all the species that could be encountered. The species covered in this chapter are those encountered at Enchanted Rock SNA, but all should be found across the Llano Region. Additional species that are not found at Enchanted Rock SNA may be found in the Llano Region, but they are not included here.

Regions Scientists are always attempting to organize and classify the natural world. Geologists, botanists, ecologists, climatologists, and scientists from other disciplines create classification systems to delineate land areas into units known as regions. Many of these classification systems are multitiered, with the region being the middle unit in a hierarchy of three or more levels.

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Physiographic Regions: Physiographic regions, as originally defined by Fenneman, are delineated using geomorphology, that is, physical characteristics and the history of the land. In this system, Enchanted Rock is in section 13j, the Edwards Plateau section. The age of rocks is shown by color. Divisions are bounded by thicker dark lines, regions are labeled by number, and sections are labeled by letter and outlined in white.

Physiographic Regions Work by Nevin Fenneman in the 1930s used geomorphology (the geological origin of rocks, their evolution, and the processes that shaped them) to delineate physiographic regions. Under his three-tiered system, the United States is partitioned into eight divisions: Canadian Shield, Atlantic Plain, Appalachian Highlands, Interior Plains, Interior Highlands, Rocky Mountain System, Intermontane Plateaus, and Pacific Mountain System. The divisions are subdivided into 25 provinces, which are 124 fl ora a n d fau na

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further subdivided into 86 sections. The Great Plains Province, running up through the middle of the United States, is one of two physiographic provinces making up the Interior Plains Division, the other being the Central Lowland Province. The Edwards Plateau Section and Central Texas Section are categorized as the two southernmost sections within the Great Plains Province.

Natural Regions Natural regions use ad hoc characteristics to delineate land areas based not only on geomorphology but also on soils, vegeta-

tion, hydrological systems, climate, or other natural factors. One natural region system, defined by research through the Lyndon B. Johnson School of Public Affairs in 1978, breaks Texas up into eleven natural regions: Piney Woods, Oak Woods, Blackland Prairie, Gulf Coast Prairie, Coastal Sand Plain, Brush Country, Edwards Plateau, Llano Uplift, Rolling Plains, High Plains, and Trans-Pecos. The Edwards Plateau region was divided into the Live Oak–Mesquite Savanna, Balcones Canyonlands, and Lampasas Cut Plain subregions, all of which are adjacent to the Llano Uplift region.

Natural Regions of Texas: Large-scale regions that have a distinctive combination of rock, soil, plant, animal, and weather conditions are known as natural regions. In this work, by the LBJ School of Public Affairs, regions are numbered and outlined in white, and letters indicate subregions. Enchanted Rock is within the Llano Uplift natural region.

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Vegetative Types Other systems examine the physiognomic and floristic characteristics of dominant cover plants to determine the boundaries of vegetative types. Physiognomic characteristics include the structure (height and spacing) and growth form (gross morphology and growth aspect) of the predominant plant species and its associated leaf characteristics (seasonality, shape, phenology, duration, size, texture). Physiognomic systems allow for vegetative generalizations at broad geographic scales. They label a community based on the dominant plant type at the uppermost stratum (the cover plant) of an area, which is typically a species of tree or shrub. Floristic systems examine species composition or species groups, often with a holistic treatment of plant associations or the relationship between soils and plant associations. One difficulty with vegetative classifications is accounting for disturbances, whether natural or man-made. For example, if all of the trees in a community of live oaks and mesquites are burned or cut down, does the land still deserve its classification as live oak–mesquite park? Ranching also has a profound effect on a plant community. Some researchers separate natural from cultivated (crop) plant communities. Others attempt to take into account the potential of a natural community. One vegetative study, completed in 1984 by the Texas Parks and Wildlife Department, identified 47 vegetative types across Texas. The dominant vegetative types in and around the Llano Region were live oak–mesquite parks, with smaller areas of

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Vegetative Cover: The dominant vegetative cover across the Llano Region is oak savanna, determined by examining the dominant, top stratum of plants for a given area, as shown in this work by the Texas Parks and Wildlife Department.

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live oak–Ashe juniper parks and live oak– mesquite–Ashe juniper parks. Scale has to be taken into account in studies like this. There certainly are more communities present within the Llano Region if the scale is reduced. For example, riparian plant communities along streams are often excluded from larger-scale studies. An effort by the Nature Conservancy attempts to normalize the methods and terminology of vegetative classifications. Adopted in a study of the national parks, it is known as the National Vegetation Classification System. It has seven levels of classification: system, class, subclass, group, formation, alliance, and association. The first five levels use physiognomic characteristics; the last two levels use floristic characteristics. “System” refers to the hydrological regime (e.g., terrestrial or aquatic). The class is determined by the spacing and height of the dominant form (e.g., woodland). The subclass is based on morphological and phenological characteristics (e.g., evergreen woodland). The group qualifies the designation using climate or latitude, growth form, and leaf form (e.g., temperate evergreen needle-leaved woodland). The formation represents mappable units. For the floristic characteristics, the alliance indicates the dominant species cover type (e.g., subalpine fir forest). Finally, the association lists any subdominant or associated species in the community (e.g., Abies lasiocarpa and Vaccinium scoparium).

Ecoregions A more integrated approach to delineating regions is based on ecology, which is the

study of the distribution and abundance of living organisms and the interaction between the organisms and the environment. Ecoregions (also called biotic provinces) base delineations on (1) the commonality of a large majority of plant and animal species, (2) sharing of similar environmental conditions, and (3) species interaction with each other and the nonliving physical factors. Ecoregions often additionally take into account geomorphology, soils, climate, or other natural factors. As with many regional classification systems, ecoregions are part of a multitiered system. At the top level are large landmasses known as ecozones. North America is in the Nearctic ecozone. Ecoregions, the middle tier, are further divided into communities, often plant communities but not exclusively so. Transitions between communities, which are not necessarily sharp, are known as ecotones. One common practice that defines the boundaries is to examine the food web (also food chain or food network). A food web is, to put it simply, the hierarchy of who eats whom. Seral stages are used to explain the maturation of a community through its intermediate stages in an ecological succession. Primary succession is the process by which a plant community (a pioneer community) occupies a previously unoccupied space; secondary succession occurs when one plant community occupies a space as a result of a disturbance (man-made or natural). A climax community is a stable plant community that is self-perpetuating and in equilibrium with its environment. An early seral stage would be one in which succession has taken place and the community

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is establishing itself. A late seral stage would be one in which the community has matured. Some researchers also define a postseral stage, where some members of the plant community begin to die out and equilibrium is lost. One important study defining ecoregion systems was done by Frank Blair in 1950. He defined seven biotic provinces within Texas: Kansan, Navahonian, Chihuahuan, Tamaulipan, Austroriparian, Texan, and Balconian. The Balconian Province encompasses the Edwards Plateau and Llano Region. A more recent ecoregion system, defined by Frank Gould in 1975, divided Texas into ten biotic provinces. Later work in 1987 by Jim Omernik defined socalled Level III ecoregions quite similar to

Ecoregions: Two systems of ecoregions are shown, one by Blair (green boundaries and labels) and the other by Omernik, known as Level III Ecoregions (colorful backgrounds with white labels), which are similar to the ecoregions defined by Gould. Enchanted Rock is in the Balconian or Edwards Plateau ecoregion, depending on the system. Notice the small differences in the boundaries of the Edwards Plateau.

the boundaries delineated by Gould, but Omernik added two additional provinces (for a total of twelve) and adjusted the boundaries of the Gould biotic provinces. In both the Gould and the Level III ecoregions, the Edwards Plateau and Llano Region are grouped together in the Edwards Plateau ecoregion, although with slightly different boundaries. Various studies have included or excluded the Llano Region, the Lampasas Cut Plain, and the Stockton Plateau as part of the Balconian (or Edwards Plateau) Province. There is not necessarily a correct interpretation.

Plant Associations at Enchanted Rock SNA The first systematic study of plant life specifically at Enchanted Rock was done in the early 1930s by Eula Whitehouse. That study described four plant communities present at Enchanted Rock: granite outcrop, oak savanna, riparian, and mesquite grassland. The study paid particular attention to the seral stages of plant succession on granite outcrops. It described how pioneer species such as lichens invade an area and establish conditions for other plants at a later seral stage of development. Succession through the seral stages continues until the environment stabilizes and climax conditions develop. The granite outcrop community was divided into two succession groups, the xerosere and the hydrosere. The xerosere related to plant successions under xeric conditions. The hydrosere consists of a plant succession in wet conditions, that is, within weathering pits.

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Yellow Stonecrop: Yellow stonecrop grows in certain shallow weathering pits, often as a monoculture. Enchanted Rock Dome is in the background.

The xerosere includes three successions, called crevice, gravel, and rock surface. The crevice succession progresses as follows: crustose lichens → foliose lichens → mosses → spike moss → annuals → perennials → oak-hickory. Crustose lichens are the pioneer species. They accelerate the weathering of the rock, leading to the formation of loose grus, a primitive, acidic protosoil. Foliose lichens thrive on more protected rock faces already attacked by weathering. They typically require a rougher face on the rock to es-

tablish a foothold. Mosses require at least a thin soil and water. As small quantities of grus deepen and stabilize, mosses and later spike moss grab a foothold where water is semireliable. With more soil development, deeper grus, and reliable water, annuals take hold. Perennials take advantage of increased stability. Finally, the soil becomes deep enough to support trees such as plateau live oak, Texas hickory, blackjack oak, or even post oak. The gravel succession progresses from spike moss → sedum → annuals → perennials → shrubs → oak-hickory.

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The rock surface succession progresses from crustose lichens → foliose lichens → mosses → spike moss → annuals → bluestem grassland. The hydrosere, consisting of plants requiring wet conditions to thrive, includes the rock pool succession, from algae–quillwort → liverwort–pygmyweed → sedges → annuals → bluestem grassland. A 1979 study by Mary Butterwick, part of a survey of the future park, reiterated the four plant associations. Oak savanna (or oak woodlands) is common across the Hill Country. A savanna is defined as a land area where small stands of trees (known as parks) are separated by areas of grass, preventing the canopy of trees from closing. Within the Texas Hill Country, where soils derived from limestone are prevalent, the dominant oak species is usually plateau live oak. In areas with sandy or gravelly soils, such as those within the Llano Region, the post oak and blackjack oak are prevalent. The plant community is known as the post oak savanna. Post oak and blackjack oaks also thrive farther to the northeast in Texas, where post oak savanna is more widespread. The mesquite grassland association is found in clay-dominated soils, such as those derived from Packsaddle schist. The dominant plant is the honey mesquite tree, scattered among a ground cover of tall grasses. Plateau live oak, cedar elm, and other trees 130

are also present. Mesquite grassland is highly susceptible to disturbance, and the effects of grazing and fire suppression have favored woody and unpalatable plants, such as honey mesquite, prickly pear, and pencil cactus to the detriment of little bluestem and other tall grass species. Today, mesquite grassland is often an impenetrable thicket of shrubby, sharp, nasty plants. The riparian association is found in the complex alluvial soils in and along creeks. Deeper soils and more reliable water support tall trees and other water-loving plants. The character of the riparian association differs depending on the type of soils and rock present. For example, within limestone areas, sycamore, cottonwood, and other water-loving trees may be the dominant trees. In soils derived from granite, a complex mix of black willow, pecan, buttonbush, and other plants may be present. Many plants, such as black willow, monkeyflower, and others requiring wet feet are found directly in creek beds. On the banks along the first terrace, deep, rich soils support tall trees and a rich variety of plants. Periodic flooding replenishes the soil and removes the weaker plants. Outward from the first terrace is a slow transition to whatever plant community is present in the surrounding area.

Plant Communities at Enchanted Rock SNA The mappable coverage area of a plant community is referred to as a plant zone. The zones correlate quite closely to the plant association boundaries defined by Whitehouse and reiterated by Butterwick. The zones are labeled granite, riparian, oak sa-

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Plant Zones at Enchanted Rock SNA: Plant zones within the park correspond to the associations defined by Whitehouse and refined by Butterwick.

vanna, and mesquite grassland. Some zones are further split into subzones to describe the conditions and plants more precisely.

Granite Zone The granite zone provides Enchanted Rock SNA with its unique character. It is found where granite is exposed on domes, tors, and outcrops. This chapter divides the zone into three subzones, each of which has different characteristics and therefore supports a different group of plants.

Granite top Zone: The granite top zone is found where exposed granite is relatively level, a condition most prevalent at the top of many but not all exfoliation domes. Boulders, especially large ones, are less common, as exfoliation sheets are typically thinner at the top of exfoliation domes. At first glance, these areas appear to be mostly barren; however, rock surfaces are covered by species of the almost black Verrucaria genus of crustose lichens, darkening the appearance of the pink granite considerably. Other colorful crustose lichens in

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Granite Top Zone: Where granite is fairly level, water collects in the natural variations in the surface. Over time, the acidic standing water makes the pit deeper and wider. Grus and eventually organic matter collect in the bottom of the pit, supporting a range of plant and animal life, especially when water is present.

shades of green, red, yellow, gray, and white have been identified as species of the Acarospora, Buellia, Caloplaca, Haematomma, Lecanora, and Xanthoria genera. They are found especially on the faces of boulders, sometimes presenting interesting and colorful displays. Foliose lichens are present on the more sheltered and weathered faces of boulders. Days after rainfall fills the weathering pits, they become vernal pools as they burst with life. Weathering pits with lessdeveloped soil support quillwort, yellow stonecrop, or perhaps no plant life. Weathering pits with deeper or more complex soil support a range of plants from edge to center. At the edge, American tripogon,

dense-tuft hair sedge, or Riddell’s spike moss can be found. Farther in, look for Canada wild onion, crow poison, prairie rain lily, and Texas wintergrass. Toward the center, where the soil is deepest, you can find little bluestem, bushy bluestem, Vasey grass, Lindheimer’s prickly pear cactus, basin sneezeweed, rock coreopsis, and an occasional pencil cactus. Small stands of plateau live oaks grow in the most established weathering pits. As for animals, the lack of shelter and plant diversity keeps their numbers low. Fairy shrimp from the Branchinecta genus hatch and twitch around in the vernal pools soon after they fill with water. A healthy number of butterflies, bees, and

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Granite Flank Zone: Thick blocks (the South American Boulders) are the remnants of an exfoliation sheet, which was quite thick here. The boulders trap grus and water and create sheltered areas where plants, including shrubs and trees, find a foothold and thrive.

hummingbirds work the flowers throughout springtime. The hummingbirds are fun to watch as they zoom in from points below and drink from prickly pear flowers in May. The few boulders at the top may support a small community of lizards. Some exfoliation dome tops, such as Freshman Mountain, are not bald but are vegetated with trees, specifically plateau live oak. Further study is required to understand how trees have gained a substantial foothold there. A seldom-visited outcrop of Packsaddle schist at the far eastern end of the park has good examples of weathering pits, albeit with slightly different characteristics from those on granite.

Granite Flank Zone: The granite flank zone has a number of differences from the granite top zone. Most important is the flow of water down the flanks; water does not stand to form weathering pits. Large boulders provide sheltered areas where grus is trapped and plants can take hold. Water is also trapped, supplying the plants with moisture. Finally, shade, slight as it may be, also aids the plants. Water is directed down the slopes via systems of channels. The channels have the effect of concentrating water collected from the top of the exfoliation dome into narrow bands along the flanks and then focusing that water into small areas at the base of the dome. The accelerated and sometimes

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substantial flow through the channels is also able to transport grus broken from boulders and the surface of the exfoliation domes into weathering pits, to the base of the dome, or eventually into the streams below. Dikes and fractures play a role similar to that of the channels. Along dikes and fractures, look for scratch daisy, slender snakecotton, orangegrass, nits-and-lice, little bluestem, lace cactus, and an occasional hedgehog cactus that has grabbed a tenuous foothold. Channels typically are scoured of grus, but life is concentrated where they flow into weathering pits. Gravel around the base of small boulders supports yellow stonecrop, Riddell’s spike moss, Wright’s spike moss, fairy swords, wooly lipferns, and wavy scaly cloakfern. Where there is more water, Kaulfuss’ lipfern may also be present. Zigzag cliff brake fern and Wright’s cliff brake fern prefer a little shelter from the sun and are often tucked between boulders, along with common woodsia, a fern that prefers shelter and water. Besides ferns, more sheltered areas with more or larger boulders support a rich set of woody plants. Trees and shrubs include plateau live oak, Texas hickory, post oak, blackjack oak, American pokeweed, Texas persimmon, Mexican buckeye, flameleaf sumac, evergreen sumac, netleaf hackberry, shrubby boneset, catclaw mimosa, and red mulberry. Vines and other decumbent plants are common, including Virginia creeper, saw greenbrier, Carolina snailseed, common ivy treebine, poison ivy, net-vein milkvine, netleaf clematis, globeberry, cotton morning glory, yellow passionflower,

and Lindheimer’s morning glory. Welldrained locations support Texas sacahuista, Lindheimer’s senna, Buckley’s yucca, white lace cactus, claret-cup cactus, pencil cactus, Texas prickly pear, plains prickly pear, and hedgehog cactus. Grasses include Texas wintergrass, little bluestem, tanglehead, switchgrass, and many others. Where water fans out on exposed granite, it supports mats of dry rock moss, Riddell’s spike moss, Wright’s spike moss, rock coreopsis, basin sneezeweed, Canada wild onion, prairie rain lily, western yarrow, crow poison, spiderwort, Texas star, and others. Unlike the unsheltered granite top zone, the granite flank zone provides innumerable places for mammals, reptiles, and birds to thrive. Canyon wrens often sing on top of large boulders. Roadrunners hunt around the boulders looking for lizards. White-tailed deer come up to drink and browse. Turkey and black vultures often perch on the larger granite boulders, sometimes in great numbers. A rarely sighted red fox may slink away if approached. Rock squirrels scamper in and around boulders. Blanchard’s cricket frogs congregate around seemingly minuscule pools of water. Tree, crevice spiny, and eastern collared lizards sun themselves on boulders. Western diamond-backed rattlesnakes come out to hunt at dusk. Granite perimeter Zone: A transition from a vertical environment to a horizontal one occurs at the base of granite domes and tors. In a few small locations within the park, well-sheltered sanctuaries from the heat have been created by the shade of tall

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Granite Perimeter Zone: In a few sheltered areas near granite domes, where deeper grus has accumulated and water is regularly available, taller stands of trees grow, such as these post oak and blackjack oak trees.

trees and the proximity to steep granite walls. Here, water slows and often flows along the perimeter of the dome or tor for a time. Grus accumulates, allowing larger trees to grow. These areas have been designated the granite perimeter zone. In these small areas are found many of the same plants that inhabit the granite flank zone. The difference is that the trees grow in small stands approaching the size of woods, often with a primitive understory of Texas persimmon, gum elastic, common beebush, poison ivy, and other woody plants. The most visited of these granite perimeter zones is Echo Canyon, the sheltered

area between Enchanted Rock Dome and Little Rock Dome. Echo Creek runs through this canyon, providing a strip of the minor riparian zone and increasing its diversity. The northern side of Enchanted Rock Dome, where the climbers try out their traditional climbing techniques, is another example. Other smaller examples are found in a few other locations.

Riparian Zone The riparian zone at Enchanted Rock SNA is found along streams. The riparian zone was broken down into two subzones, the

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Riparian Zone: Water from Sandy Creek and rich alluvial deposits support a diverse set of plants on the creek bed and on the first terrace where floods occasionally occur.

major riparian zone and the minor riparian zone. The major riparian zone is found along Sandy Creek, Walnut Springs Creek, and a small portion of North Walnut Springs Creek. The major riparian zone has three parts, the streambed, the first terrace, and the transition area (which may consist of additional terraces). The streambeds of Sandy Creek, Walnut Springs Creek, and North Walnut Springs Creek are all filled with grus. During ordinary stream flow and more so during

major riparian Zone:

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flooding, the grus has often been sorted by size, with coarser grus in the current main channel and finer, more rounded and weathered grus farther outward. The streams are often braided, with multiple small channels of water threading through the bed, helping to sort out particles by size. The path of the main channel changes frequently as a result of heavy rain events. Streams in the vast majority of the Edwards Plateau flow through limestone, where little soil is present and water flow is directly on top of bedrock. In the streams within Enchanted Rock, during periods of low water flow, water flow is under the surface. Even

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in places where granite is exposed, there may be no surface water flow. To thrive in the streambed, plants must be anchored solidly enough to withstand regular flooding. Look for black willow, cottonwood, Roosevelt weed, buttonbush, Johnsongrass, Lindheimer’s muhly, Indiangrass, switchgrass, eastern gramagrass, purpletop, monkeyflower, Texas bluebonnet, mustang grape, cattail, and various species of sedge and rush. When stream flow ceases, green algae blooms choke the remaining pools of standing water until they dry. Blanchard’s cricket frogs and Rio Grande leopard frogs congregate where water is present, sometimes in impressive concentrations if water levels are low. Diamond-backed water snakes and ribbon snakes work in or right along the water. Schools of small fish and tadpoles live in the pools, dependent on the rainfall to keep the stream flowing before their pool dries up. Dragonflies and damselflies hang close to the water, catching insects and depositing eggs in stagnant water. Water strider bugs float on the surface of the water. Butterflies (like the red admiral and goatweed leafwing), honey bees, and wasps (such as the yellow-kneed) visit damp spots to drink. Nocturnal mammals such as whitetailed deer and raccoons visit at dusk. Birds work the bushes and trees. A few birds, like the great gray heron, find a pool to fish in. Just outside and away from the streambed is the first terrace. Unlike the streambed, where grus is the primary soil, the terrace has richer, more complex alluvial soil, made up not only from the breakdown of granite but also consisting of plant mat-

ter and even material from upstream rock types. Trees, shrubs, grasses, and flowering plants thrive. The trees grow quite tall in some areas, especially where a minor waterway comes into the larger stream. The first terrace extends away from the stream, sometimes for as much as hundreds of feet. Most notably absent from the first terrace are the black willow trees, cattail, sedges and rush, and monkeyflower, which must have a reliable source of water. Woody plants include pecan, Texas buckeye, rough nama, Texas persimmon, sugar hackberry, red mulberry, cedar elm, American elm, Texas hickory, plateau live oak, gum elastic, buttonbush, beebush, mustang grape, and greenbrier. Flowers include snow-on-the-mountain, goldeneye phlox, cowpen daisy, buffalo gourd, frostweed, silverleaf nightshade, western horse nettle, buffalobur, Texas vervain, Texas thistle, Texas prickly poppy, lantana, Texas bluebonnet, Mexican hat, gumweed, late boneset, various crotons, southern dewberry, Indian paintbrush, fleabane, and others. Grasses are similar to those well-rooted species found in the streambed but now include species like silver bluestem, threeawn, sideoats grama, needle grama, Texas grama, King Ranch bluestem, bristlegrass, common sandbur, hooded windmillgrass, tumble windmillgrass, paspalum, Canada and Virginia wild rye, various lovegrass species, and many others. The first terrace is the domain of the grasshopper, where members of the Melanoplus, Schistocerca, and Mermiria genera can be found in the grasses along the banks. Butterflies appreciate the rich selection of flowers, especially the cowpen

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Cedar Elm Color: In early to mid-December, the leaves of tall cedar elm trees in the Major Riparian Zone along Sandy Creek often turn a pleasant yellow.

daisies and frostweed, which bloom later in the summer and early fall. At that time, expect to find an amazing concentration and diversity of butterflies, including queen, monarch, hackberry, common buckeye, leafwing, variegated and gulf fritillary, question mark, various sulphurs, checkered skipper, sachem, fiery skipper, American and painted lady, red admiral, and others too numerous to mention. Both Sandy Creek and Walnut Springs Creek lack an extensive upstream watershed. The consequences of this are many. First, both streams tend to lose their surface flow quickly. On the other hand, heavy rains do bring flooding to the streams, but

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the streams do not often leave their banks. The lack of flooding outside the streambed limits the creek’s ability to build a second terrace. A number of springs within the park provide a critical lifeline to animals during droughts, as there may be no other standing water present in the park. Farther away from the stream, with its alluvial soil, periodic flooding, and availability of water, the major riparian zone shows increasing characteristics of whatever plant association the stream cuts through. While traveling through Enchanted Rock SNA, Sandy Creek flows through a mesquite grassland zone on one side and an oak savanna or granite zone on

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the other bank. Walnut Springs Creek cuts through oak savanna. Minor waterways play an important role in supporting plants and animals. Because they are so important to the diversity of life within the park, they are designated herein as their own narrow zones, the minor riparian zone. The minor riparian zone consists of narrow waterways that drain the higher elevations of granite domes and outcrops. The zone is typically no more than 10–20 feet on either side of the waterway. The plant species are heavily intermixed with plants from whatever plant community the waterway runs through. None of these waterways is officially named, but names have been assigned to them within this work. Examples are along Echo Canyon Creek, Moss Creek, Campside Creek, North Creek, Freshman Mountain Creek, and North Walnut Springs Creek. Minor streams are at best intermittent. Their flow quickly ends after rains, but some do retain stream flow many weeks after periods of sustained rains. The most reliable locations for water along their short courses are where the water pools. The two ponds within the park, Moss Lake and Frog Pond, also demonstrate riparian characteristics. Both are man-made tanks created by small earthen berms. The small ponds, which supply permanent water except in the most prolonged droughts, provide an environment where waterloving plants and animals can be found. Many interesting plants are more commonly found in or along minor streams than along Sandy Creek or Walnut Springs

minor riparian Zone:

Creek. These include the basin bellflower, Venus looking-glass, Drummond’s and egg-leaf skullcap, ten-petal thimbleweed, common least daisy, yarrow, and others. Near pools of standing water, grasses like switchgrass, Johnsongrass, and bushy bluestem are common. Pools can also support trees and shrubs that would normally be found on the first terrace of the major riparian zone, such as American elm, buttonbush, Texas buckeye, and others. The minor riparian zone does not support plants normally found in the streambed part of the major riparian zone, such as black willow, cottonwood, and other plants that require fairly constant moisture. The minor riparian zone also supports water-loving insects such as grasshoppers (in the grasses), damselflies, and dragonflies. Around the tanks, look for smooth water primrose, rough cocklebur, various sedges, Rio Grande leopard frogs, and turtles.

Oak Savanna Zone Enchanted Rock SNA sits at the extreme southeastern edge of the Enchanted Rock Batholith. Within the park, Sandy Creek runs along the boundary of the batholith, separating Packsaddle schist from granite. Clay-rich soils derived from Packsaddle schist to the south and east of Sandy Creek differ from the loose, potassium-rich soils derived from granite to the north and west of Sandy Creek. Oak savannas consist of small stands of trees separated from other tree clumps by grassy areas. A 1984 Texas Parks study of

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Oak Savanna Zone: Post oak parks consist of small stands of medium-sized post oak trees with a scattering of other trees, broken up by areas of grass.

vegetation types defines such an area as a park consisting of “Woody plants mostly equal to or greater than nine feet tall generally dominant and growing as clusters, or as scattered individuals within continuous grass or forbs (11 to 70 percent woody canopy cover overall).” The gravelly nature of the soil, with a correspondingly lower waterholding capacity (compared with the mesquite grassland zone), reduces the overall plant coverage. In general, walking through the oak savanna is easy going and pleasant. The trees are not overly tall, and they frequently lack a developed understory. The Edwards Plateau supports numerous plant associations in savanna and woods configurations, many dominated by either plateau live oak or Ashe juniper. Within the Llano Region, where granite-derived soils

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are present, the dominant trees are the post oak and blackjack oak. Parks dominated by plateau live oaks are also found on granitederived soils, including at Enchanted Rock SNA. It is often difficult to delineate the boundaries, but in general the plateau live oaks prefer ridges and the post oaks and blackjack oaks are in the valleys, taking advantage of the slightly higher availability of water. You may also find Ashe juniper, Texas hickory, small cedar elms, Texas persimmon, agarito, and saw greenbrier. Grasses include little bluestem, silver bluestem, hairy grama, Texas wintergrass, sideoats grama, various threeawn species, and others. Cactus species include the Texas and brown-spined prickly pear, nipple cactus, and pencil cactus. With the increased cover, flowering plants are less prevalent

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Mesquite Grassland Zone: The mesquite grassland zone has open areas of grass interspersed with prickly pear, pencil cactus, and other plants, with sparse stands of honey mesquite trees.

than in other zones, but include the common least daisy, western yarrow, and others. The large gray bird grasshopper flies into trees when disturbed. The massive wrinkled grasshopper, obscure grasshopper, and various species of the Melanoplus, Arphia, and Orphulella genera are present in the open grasses. Butterflies such as Reakirt’s blue and western pygmy blue, question mark, monarch, Arizona sister, red admiral, and lyside sulphur are present. A wide variety of birds can also be found. The sound of cicadas may be deafening at times.

Mesquite Grassland Zone The mesquite grassland zone is found on clay soils derived from Packsaddle schist to the south and east of Sandy Creek, ex-

tending outside the park boundary across Highway 965. The mesquite grassland zone near Enchanted Rock SNA appears to indicate extensive disturbance. What was probably originally a landscape dominated by large areas of grassland, including little bluestem, silver bluestem, and other tall grasses with scattered honey mesquite trees, is now a sometimes impenetrable thicket of nasty, sharp plants all out to get you. The clay soil’s ability to retain moisture leads to high levels of plant coverage, in comparison with the oak savanna zone. Walking through the mesquite grassland zone can be an exercise in masochism, and it should not be attempted without hiking shoes and long, heavy pants. Besides the shrubby honey mesquite trees, with their

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long spikes on the branches, the pencil cactus is quite vicious. If the pencil cactus doesn’t get you, the Texas prickly pear or brown-spined prickly pear will. Grasses include hairy grama, silver bluestem, sideoats grama, various species of threeawn, and others. Scattered, stunted plateau live oak, cedar elm, and Texas persimmon trees are also present. Other plants include Buckley’s yucca, Texas thistle, silverleaf nightshade, Texas vervain, rock coreopsis, and basin sneezeweed. White-tailed deer are somehow able to pick their way through the vegetation. An ample supply of fire ants rounds out the nasty creature lineup.

Man-made and Climate-Based Vegetation Changes The climate has been warming up and drying out since the end of the last glacial period. Roughly 15,000 years ago, species such as birch, ash, maple, and basswood in a woodland setting were more widespread in Central Texas. By 10,000 years ago, the drying climate began to favor grasses over woodlands, and by 5,000 years ago, open savanna was the dominant climax vegetation in much of the Edwards Plateau. The steady drying out led to widespread xeric conditions, where evaporation exceeds precipitation, creating a moisture deficit. Xeric conditions support western species with desert affinities, such as Lindheimer’s prickly pear, white lace cactus, and hedgehog cactus. On the other hand, ample precipitation supports trees and plants with eastern affinities, such as the post oak and blackjack oak. At the end of the eighteenth century,

large herds of bison migrated to the Edwards Plateau, and they, along with antelope, grazed on the grasses. Fires, started by lightning but also for intentional burning by Native Americans, were a regular occurrence. The combination of the bison, antelope, and fires kept the land mostly grassland, with a great diversity of forbs. By the middle to late nineteenth century, the bison herds had been eliminated, as had most of the antelope and any large game such as bears, wolves, and mountain lions. Ranching, with cattle, goats, and sheep, became widespread, and fires were suppressed. The result was a loss of grassland in favor of brushland and woods, including a dramatic increase in coverage of Ashe juniper. The grass mix changed, with little bluestem and other medium or tall prairie grasses giving way to shorter grasses. Other plants unpalatable to livestock, such as prickly pears and honey mesquite, also proliferated. Honey mesquite, once more restricted, readily spread across the Hill Country. The white-tailed deer population also exploded. Central Texas today supports some of the densest of whitetailed deer populations in the United States. Areas that are heavily affected by white-tailed deer have a distinctive browse line, where deer have eaten the leaves and tender twigs of woody plants below about 4 feet. Cattle no longer graze within Enchanted Rock SNA, since its establishment in 1979, allowing a slow recovery to take place. Little bluestem and a wide variety of other tall native grasses are once again present, growing above waist-level on the west end of the park. In the 1930s study

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of Enchanted Rock, only a single post oak tree was found; today, that population seems to have recovered nicely. On the other hand, Styrax platanifolius was noted then but now appears to have been expunged from the park. Threats continue today, including from collectors, the introduction of invasive species, and overgrazing by white-tailed deer. Enchanted Rock SNA is a relatively small footprint in the wider Llano Region and Edwards Plateau, which still deals with the pressures of ranching.

Endemic and Unusual Flora at Enchanted Rock SNA Texas has within its borders roughly 400 endemic species of plants (species found only within Texas), and the Edwards Plateau supports 100 endemic species. The highest density of endemics is found in counties along the Balcones Escarpment. Some endemic species like the Texas bluebonnet have very large ranges. Others, like the basin bellflower, found only in the Llano Region, may have a very small range. The Llano Region also supports plants that are outside their ordinary range. A good example is the hammock fern, found at Enchanted Rock SNA and nowhere else in Texas. The hammock fern’s normal range occurs in the mountains of northern Mexico, and it is found in a few isolated locations in states along the Gulf Coast. The hammock fern is not, therefore, endemic to Texas, but it still qualifies as unusual. A sampling of endemic or otherwise unusual species found within the Llano Region can be found in Appendix B.

Flora and Fauna Identification The remainder of this chapter is focused on identification of the plants and animals found specifically at Enchanted Rock SNA. The flora and fauna species lists are restricted to organisms found by the author within the park boundaries. The park is a large, less disturbed, and publicly accessible piece of land. Also, more and better studies have been conducted in the park than in most other areas, and plant lists from previous surveys were available. The most thorough studies of Enchanted Rock SNA’s plant and animal life were done in 1931 and 1979; the 1979 survey was done in conjunction with the transfer of the park to state ownership. The plant list was supplemented and updated in 1990. Other species have been added based on observations in the course of the author’s visits to the park. Birds, mammals, reptiles, butterflies, dragonflies, and damselflies are fairly well studied, but except for birds and mammals, the exact range of species may still not be fully understood. Most other insect species have not been systematically surveyed. Enchanted Rock SNA alone supports more than 500 plant species. Within Llano, Gillespie, and Mason counties, there are at least 170 bird species, 113 dragonfly and damselfly species, and hundreds of other types of animals and insects. The total number of species that could be found at Enchanted Rock SNA is easily in the thousands. There are certainly more species present in the Llano Region than are included here. Varying conditions created by different

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rock types, riparian zones, sheltered canyons, caves, and other localized landforms support additional and sometimes specialized species. Expanding beyond Enchanted Rock SNA to the greater Llano Region, however, complicates efforts to differentiate between Hill Country and Llano Uplift flora and fauna. Limestone, sandstone, and other more recent geological member layers are present in the Llano Uplift, greatly increasing the flora and fauna present. Therefore, the focus was kept strictly on Enchanted Rock SNA. As a book for casual observers, its organization of the plants and animals is not strictly along scientific lines. For example, a casual observer categorizes a honey mesquite tree as a tree, not as a member of the bean family to be grouped with the Texas bluebonnet. Nor is it consistent across the plants and animals. Flowers are grouped by color, then family, then species; moths by Hodges number; reptiles by family,

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then species. Species and genus names are included for the more experienced visitor. Remember that many plants and animals are visible only at a given time of the year. If you are visiting in the middle of winter, you may see lots of ferns, but not a single lizard or rock squirrel. Note that the species included are those found by the author. The Web site www.enchantedrock. com has more complete species lists, including species that should be in range and possibly present at the park. Good luck finding all the wildlife there is to see in this challenging and rewarding place. Enchanted Rock SNA has an incredible diversity of plants and animals for such a small area. Most visitors who only make the trek to the top of Enchanted Rock Dome never see this diversity. Hike the trails and see how well you can do spotting some of the interesting and beautiful life forms in the park.

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Plants

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Trees, Shrubs, and Vines Trees and Shrubs Trees and shrubs are upright, self-supporting plants with woody stems or trunks. A tree typically (but not always) has a single trunk and grows more than 10 feet tall. A shrub typically has multiple trunks at its base, and its height remains under 10 feet. If the plant is woody but not self-supporting, then it is classified as a vine (covered in the next section). Often, plants that are not woody but are decumbent, procumbent, or prostrate are also classified as vines. There are exceptions to these general rules. In Enchanted Rock SNA, deciduous trees leaf out starting in late February and continuing through early May. The earliest trees to leaf out and flower are the Mexican buckeyes and Texas buckeyes. The post oaks and blackjack oaks leaf out in March. The live oaks also leaf out in March, dropping last season’s leaves at that time. American elms and especially pecans are late to leaf out, with leaves emerging in late April.

Enchanted Rock SNA in some years has a touch of fall color starting in early November through early January. The best fall color occurs when there is an early hard freeze followed by prolonged cool temperatures. Most likely to be noticed for their fall color are the prairie flameleaf sumac (brilliant red). cedar elm (cheerful yellow or brown), or blackjack oak (dark red to orange). Make sure you do not collect the lovely red leaves of poison ivy! For many years, a plateau live oak lived atop Enchanted Rock in one of the larger weathering pits. Unfortunately, the mother tree died in the extended drought around 1999, but there are small trees growing around it today. The stunted mother tree’s age has not been determined. Since trees and shrubs cross numerous plant families, this collection includes the family along with the species name. Trees are sorted by family name, then species name.

anacardiaceae—Sumac Family

Rhus lanceolata, Prairie Flameleaf Sumac

Rhus virens, Evergreen Sumac

Toxicodendron radicans, Poison Ivy

Baccharis neglecta, Roosevelt Weed

Eupatorium havanense, Shrubby Boneset

aSteraceae—SunFlower Family

Toxicodendron radicans, Poison Ivy

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capriFoliaceae—honeySuckle Family

berberidaceae—barberry Family

Mahonia trifoliolata, Agarito

cupreSSaceae—cypreSS Family

Viburnum rufidulum, Rusty Blackhaw

ebenaceae—ebony Family

Juniperus ashei, Ashe Juniper

Diospyros texana, Texas Persimmon

Fabaceae—pea Family

Eysenhardtia texana, Texas Kidneywood

Mimosa aculeaticarpa var. biuncifera, Catclaw Mimosa

Prosopis glandulosa, Honey Mesquite

Quercus fusiformis, Plateau Live Oak

Quercus fusiformis, Plateau Live Oak

Quercus marilandica, Blackjack Oak

Quercus stellata, Post Oak

FaGaceae—beech Family

Styphnolobium affine, Eve’s Necklace

Quercus laceyi, Lacey Oak

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Quercus laceyi, Lacey Oak

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juGlandaceae—walnut Family

hippocaStanaceae— horSe cheStnut Family

Quercus stellata, Post Oak

Aesculus glabra var. arguta, Texas Buckeye

moraceae—mulberry Family

Carya illinoinensis, Pecan

Carya texana, Texas Hickory

Morus rubra, Red Mulberry

roSaceae—roSe Family

oleaceae—olive Family

(For Crataegus crus-galli, or Cockspur Hawthorn, see Flowers, White/Green)

Forestiera pubescens, Elbowbush

Fraxinus pennsylvanica, Green Ash

rubiaceae—madder Family

Malus sp., Crabapple genus

Cephalanthus occidentalis, Common Buttonbush

Prunus persica, Peach

rutaceae—rue Family

Salicaceae—willow Family

Ptelea trifoliata, Common Hoptree

Zanthoxylum hirsutum, Tickle-tongue

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Sapindaceae—Soapberry Family

Populus deltoides, Eastern Cottonwood

Ungnadia speciosa, Mexican Buckeye

Salix nigra, Black Willow

tamaricaceae—tamariSk Family

Sapotaceae—Sapodilla Family

Sideroxylon lanuginosum, Gum Elastic

Tamarix sp., Salt Cedar

ulmaceae—elm Family

Celtis laevigata, Sugar Hackberry

Celtis laevigata var. reticulata, Netleaf Hackberry

Ulmus americana, American Elm

verbenaceae—verbena Family (For Lantana urticoides, or Texas Lantana, see Flowers, Red/Orange)

Ulmus crassifolia, Cedar Elm

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Aloysia gratissima, Common Beebush

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Vines Vines are plants that are not self-supporting. Some definitions require that a vine be woody, others only that they be prostrate or decumbent. Both woody and nonwoody vines are included here, but in many cases the flower photograph for the vine is referenced. By far the most exciting vine or shrub you may encounter is poison ivy. It is not widespread, but it is found in enough locations to get you into trouble if you are sensitive to it (10 percent of the population has no reaction to poison ivy). Hope that you recognize it before it finds you, because once the oils have penetrated your skin, you will regret it. There is a large community of poison ivy in its shrub form near the top of Enchanted Rock Dome. Another vine that may cause problems, as some people are sensitive to it, is the ivy treebine, which like poison ivy also has “leaves of three.” Virginia creeper is common and provides

anacardiaceae—Sumac Family

(For Toxicodendron radicans, Poison Ivy, see Trees and Shrubs)

ariStolochiaceae—birthwort Family

(For Aristolochia coryi, Cory’s Dutchman’s Pipevine, see Flowers, Red/Orange)

convolvulaceae—morninG Glory Family

beautiful red fall color in November and December. Many of the vines in the park have amazingly beautiful leaves and flowers. Cory’s Dutchman’s pipevine, Lindheimer’s morning glory, yellow passionflower, purple leatherflower, butterfly pea, net-vein milkvine, cotton morning glory, and sensitive brier, just to name a few, all have very showy or intriguing flowers. Lindheimer’s globeberry presents beautiful red plum-sized fruits in late fall into winter. The net-vein milkvine has beautiful green flowers and strange-looking pods. Along Sandy Creek and Walnut Springs Creek, look for mustang grape vines, which climb up into trees, taking over their branches. You may find large saw greenbrier or Carolina snailseed along the granite flank zone or in other protected, wooded areas.

aSclepiadaceae—milkweed Family

(For Cynanchum barbigerum, Bearded Swallowwort; Cynanchum racemosum var. unifarium, Talayote; and Matelea reticulata, Net-vein Milkvine, see Flowers, White/ Green)

campanulaceae—bellFlower Family

(For Triodanis biflora or T. perfoliata, Small or Clasping Venus Looking-glass, and Triodanis leptocarpa, Slim-pod Venus Looking-glass, see Flowers, Pink/Purple/Blue)

cucurbitaceae—Gourd Family

(For Cyclanthera dissecta, Bur Cucumber, see Flowers, White/Green; for Ibervillea lindheimeri, Lindheimer’s Globeberry, see Flowers, Yellow, and Berries, Seeds, Pods, and Fruit)

(For Convolvulus equitans, Texas Bindweed, and Cuscuta sp., Dodder, see Flowers, White/ Green) (For Evolvulus alsinoides, Slender Dwarf Morning Glory; Ipomoea cordatotriloba var. torreyana, Cotton Morning Glory; and Ipomoea lindheimeri, Lindheimer’s Morning Glory, see Flowers, Pink/Purple/Blue. For Evolvulus sericeus, Silky Evolvulus, see Flowers, White/Green) Dichondra recurvata, Oakwoods Ponysfoot

Cucurbita foetidissima, Buffalo Gourd

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euphorbiaceae—SpurGe Family

Fabaceae—pea Family

krameriaceae—ratany Family

(For Astragalus nuttallianus var. austrinus, Small-flower Milk Vetch; Centrosema virginianum, Butterfly Pea; Mimosa hystricina, Bristly Sensitive Brier; Rhynchosia senna var. texana, Texas Snoutbean; Strophostyles helvola, Amberique Bean; Strophostyles leiosperma, Slickseed Fuzzy Bean; Vicia ludoviciana, Deer Pea Vetch; and Vicia minutiflora, Small-flower Vetch, see Flowers, Pink/Purple/Blue. For Strophostyles helvola, Amberique Bean, also see Berries, Seeds, Pods, and Fruit)

(For Krameria lanceolata, Trailing Krameria, see Flowers, Red/Orange)

paSSiFloraceae—paSSionFlower Family

ranunculaceae—buttercup Family

Tragia ramosa, Catnip Noseburn

meniSpermaceae—moonSeed Family

Cocculus carolinus, Carolina Snailseed

roSaceae—roSe Family

Smilacaceae—catbrier Family

Rubus trivialis, Southern Dewberry

Smilax bona-nox, Saw Greenbrier

vitaceae—Grape Family

Vitis mustangensis, Mustang Grape

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Cissus incisa, Ivy Treebine

Parthenocissus quinquefolia, Virginia Creeper

Vitis mustangensis, Mustang Grape

Vitis mustangensis, Mustang Grape

Vitis berlandieri, Spanish Grape

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Flowers The flower display is more subtle at Enchanted Rock SNA than that found in the larger Llano Region, where flowers often blanket the field. Flowers can be found in any season at Enchanted Rock SNA. The flowering season starts in late January or February when the ten-petal thimbleweed, tiny bluet, pink vervain, Drummond’s skullcap, fumewort, and shepherd’s purse begin to emerge, maintaining a small collection of butterflies. A few Hooker’s scratch daisies may still be present from the previous fall if there were no prolonged periods of freezing temperatures. The beautiful flowers of the Texas buckeye trees burst out in late February to mid-March, followed soon thereafter by the post oak, plateau live oak, and blackjack oak, attracting large numbers of emerging butterflies and moths. Flowering cedar elm trees can be heard from quite far away, as honey bees buzz while collecting pollen from their flowers. By late March, a veritable explosion of flowering occurs, even if rainfall has been poor. The red flowers of claret-cup cactus appear, along with crow poison, agarito, bladderpod, Drummond’s wild garlic, prairie rain lily, small-flower milk vetch, deer pea vetch, stiff-stem flax, white prickly poppy, hairy-fruit chervil, goldeneye phlox, large-flower buttercup, Mexican buckeye, rusty blackhaw, Texas bluebonnet, common least daisy, spiderwort, and many others too numerous to list. April brings another impressive list of flowers, including rock coreopsis, blue curls, Lindheimer’s morning glory, American germander, bracted pas-

sionflower, winecup, Texas bull nettle, common beebush, antelope horns, narrow-leaf yucca, sacahuista, basin sneezeweed, Canada wild onion, Texas persimmon, and many others still blooming from March. In late April going into May, Texas and plains prickly pear cacti are in bloom, bringing bursts of color throughout the park and attracting many hummingbirds. Many of the vines and flowers with woody stems start blooming in May through June. By late spring going into summer, the blooming begins to taper off, as heat and diminishing rainfall dry everything up. A few species continue blooming into the summer, including buttonbush, lantana, butterfly pea, leatherflower, various croton species, cotton morning glory, Texas skeleton plant, bristly sensitive brier, rough nama, Texas star, egg-leaf skullcap, silky evolvulus, slender snakecotton, annual wild buckwheat, poorjoe, snow-on-the-mountain, orangegrass, nits-andlice, and many others. Late summer into fall brings the final batch of flowers, including shrubby boneset, late boneset, frostweed, Hooker’s scratch daisy, Texas broomweed, curly-cup gumweed, Roosevelt weed, and cowpen daisy. Butterfly and bee activity around shrubby boneset is especially intense. Flowers are ordered first by color, then by family, then by species. Some flowers come in multiple colors. If you cannot find a flower, try looking under a different color; for example, many pink flowers may be almost white.

Pink/Purple/Blue AsterAceAe—sunflower fAmily

Carduus nutans, Musk Thistle

Carduus tenuflorus, Slender Bristle Thistle

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Cirsium texanum, Texas Thistle

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Liatris punctata, Dotted Blazing Star

Lygodesmia texana, Texas Skeleton Plant

Palafoxia callosa, Small Palafoxia

Symphyotrichum sp., Aster genus

CaCtaCeae—CaCtus Family

BrassiCaCeae—mustard Family

Arabis petiolaris, Brazos Rock Cress

Echinocereus reichenbachii ssp. reichenbachii, White Lace Cactus

CampanulaCeae—BellFlower Family

Mammillaria heyderi var. heyderi, Nipple Cactus

Campanula reverchonii, Basin Bellflower

Triodanis biflora or T. perfoliata, Small or Clasping Venus Looking-Glass

Commelina erecta var. angustifolia, Narrowleaf Dayflower

Tinantia anomala, False Dayflower

Tradescantia pedicellata, Edwards Plateau Spiderwort

Tradescantia pedicellata, Edwards Plateau Spiderwort

CommelinaCeae—spiderwort Family

Triodanis leptocarpa, Slim-pod Venus LookingGlass

Tradescantia gigantea or T. occideltalis, Giant or Prairie Spiderwort

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Tradescantia gigantea or T. occideltalis, Giant or Prairie Spiderwort

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convolvulaceae—morninG Glory Family

Convolvulus equitans, Texas Bindweed

Evolvulus alsinoides, Slender Dwarf Morning Glory

Fabaceae—pea Family

euphorbiaceae—SpurGe Family

Ipomoea lindheimeri, Lindheimer’s Morning Glory

Ipomoea cordatotriloba var. torreyana, Cotton Morning Glory

Chamaesyce prostrata, Spotted Spurge

Astragalus nuttallianus var. austrinus, Small-flower Milk Vetch

Centrosema virginianum, Butterfly Pea

Lespedeza stuevei, Tall Bush Clover

Lupinus texensis, Texas Bluebonnet

Mimosa hystricina, Bristly Sensitive Brier

Strophostyles helvola, Amberique Bean

Strophostyles leiosperma, Slickseed Fuzzy Bean

Vicia ludoviciana, Deer Pea Vetch

Gentianaceae—Gentian Family

Vicia minutiflora, Small-flower Vetch

Geraniaceae—Geranium Family

Sabatia campestris, Texas Star

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hydrophyllaceae—waterleaF Family

Erodium cicutarium, Pin Clover

Nama hispidum, Rough Nama

iridaceae—iriS Family

lamiaceae—mint Family

Sisyrinchium chilense, Swordleaf Blue-eyed Grass

Phacelia congesta, Blue Curls

Hedeoma acinoides, Slender Hedeoma

Nemophila phacelioides, Baby Blue Eyes

Hedeoma drummondii, Drummond’s False Pennyroyal

Lamium amplexicaule (leaves only), Henbit

Monarda citriodora, Lemon Beebalm

liliaceae—lily Family

Scutellaria drummondii, Drummond’s Skullcap

Scutellaria ovata, Egg-leaf Skullcap

Teucrium canadense, American Germander

malvaceae—mallow Family

Allium drummondii, Drummond’s Wild Garlic

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nyctaGinaceae—Four o’clock Family

Callirhoe involucrata, Winecup

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onaGraceae—eveninG primroSe Family

Boerhavia coccinea, Scarlet Spiderling

Mirabilis sp., Four-O’Clock genus

Mirabilis sp., Four-O’Clock genus

oxalidaceae—wood Sorrel Family

Gaura parviflora, Lizardtail Gaura

polemoniaceae—phlox Family

Oxalis drummondii, Drummond’s Oxalis

portulacaceae—purSlane Family

Giliastrum incisum, Split-leaf Gilia

Phlox drummondii var. mcallisteri, Drummond’s Phlox

Portulaca pilosa, Shaggy Portulaca

ranunculaceae—buttercup Family

Anemone berlandieri, Ten-petal Anemone

Talinum parviflorum, Dwarf Flameflower

Anemone berlandieri, Ten-petal Anemone

roSaceae—roSe Family

Anemone berlandieri, Ten-petal Anemone

Clematis pitcheri, Leatherflower

Clematis pitcheri, Leatherflower

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rubiaceae—madder Family

Malus sp., Crabapple genus

Prunus persica, Peach

Diodia teres, Poor-Joe

Sapindaceae—Soapberry Family

Houstonia pusilla, Tiny Bluet

Ungnadia speciosa, Mexican Buckeye

Stenaria nigricans var. nigricans, Prairie Bluet

Scrophulariaceae—FiGwort Family

Solanaceae—potato Family

Nuttallanthus texanus, Texas Toadflax

Veronica persica, Persian Speedwell

tamaricaceae—tamariSk Family

Solanum dimidiatum, Western Horse Nettle

Solanum elaeagnifolium, Silverleaf Nightshade

Tamarix sp., Salt Cedar genus

verbenaceae—verbena Family

Glandularia bipinnatifida var. bipinnatifida, Dakota Vervain

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Glandularia pumila, Pink Vervain

Verbena halei, Texas Vervain

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red/orange

aSteraceae—SunFlower Family

ariStolochiaceae—birthwort Family

Aristolochia coryi, Cory’s Dutchman’s Pipevine

Gaillardia pulchella, Indian Blanket

cactaceae—cactuS Family

Gaillardia pulchella, Indian Blanket

Ratibida columnifera, Mexican Hat

Echinocereus coccineus var. coccineus, Claret-cup Cactus

campanulaceae—bellFlower Family

Fabaceae—pea Family

Lobelia cardinalis, Cardinal Flower

Opuntia engelmannii var. lindheimeri, Texas Prickly Pear juGlandaceae—walnut Family

Pediomelum rhombifolium, Round-leaf Scurfpea

krameriaceae—ratany Family

Carya texana, Texas Hickory

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lamiaceae—mint Family

Krameria lanceolata, Trailing Krameria

Scrophulariaceae—FiGwort Family

Salvia coccinea, Texas Sage

Sterculiaceae—cacao Family

Castilleja indivisa, Indian Paintbrush

verbenaceae—verbena Family

Hermannia texana, Mexican Mallow

Lantana urticoides, Texas Lantana

white/green

aGavaceae—aGave Family

amaranthaceae—amaranth Family

Yucca constricta, Buckley’s Yucca

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Alternanthera caracasana, Mat-chaff Flower

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anacardiaceae—Sumac Family

Froelichia gracilis, Slender Snakecotton

Gossypianthus lanuginosus, Cotton-flower

Amaranthaceae, Amaranth flower

apiaceae—carrot Family

Rhus lanceolata, Prairie Flameleaf Sumac

Chaerophyllum tainturieri, Hairy Fruit Chervil

Hydrocotyle verticillata, Whorled Water Pennywort

Asclepias asperula, Antelope Horns

Asclepias oenotheroides, Hierba de Zizotes

aSclepiadaceae—milkweed Family

Torilis arvensis, Spreading Hedge Parsley

aSteraceae—SunFlower Family

Cynanchum barbigerum, Bearded Swallowwort

Cynanchum racemosum var. unifarium, Talayote

Matelea reticulata, Net-vein Milkvine

Achillea millefolium var. occidentalis, Western Yarrow

Aphanostephus skirrhobasis, Lazy Daisy

Aphanostephus skirrhobasis, Lazy Daisy

Artemisia ludoviciana, White Sagebrush

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Baccharis neglecta, Roosevelt Weed

Chaetopappa asteroides, Common Least Daisy

Erigeron sp., Fleabane

Eupatorium havanense, Shrubby Boneset

Eupatorium serotinum, Late Boneset

Hymenopappus scabiosaeus var. corymbosus, Old Plainsman

Pinaropappus roseus, Small Rock Lettuce

Symphyotrichum sp., Aster genus

boraGinaceae—boraGe Family

Verbesina virginica, Frostweed

Capsella bursa-pastoris, Shepherd’s Purse

braSSicaceae—muStard Family

Lappula occidentalis var. cupulata, Hairy Stickseed

Draba platycarpa, Broadpod Draba

buddlejaceae—butterFly buSh Family

Lepidium virginicum, Virginia Peppergrass

Nasturtium officinale, Watercress

capparaceae—caper Family

Polypremum procumbens, Juniperleaf

Polanisia dodecandra ssp. trachysperma, Sandyseed Clammyweed

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capriFoliaceae—honeySuckle Family

caryophyllaceae—pink Family

Viburnum rufidulum, Rusty Blackhaw

Cerastium glomeratum, Sticky Chickweed

chenopodiaceae—GooSeFoot Family

commelinaceae—Spiderwort Family

Chenopodium berlandieri, Pitseed Goosefoot

Stellaria media, Common Chickweed

convolvulaceae—morninG Glory Family

Tradescantia gigantea or T. occidentalis, Giant or Prairie Spiderwort

Convolvulus equitans, Texas Bindweed

cucurbitaceae—Gourd Family

cuScutaceae—dodder Family

Cyclanthera dissecta, Bur Cucumber

Evolvulus sericeus, Silky Evolvulus

ebenaceae—ebony Family

Cuscuta sp., Dodder genus

Convolvulus equitans, Texas Bindweed

euphorbiaceae—SpurGe Family

Diospyros texana, Texas Persimmon

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Acalypha gracilens, Slender Copperleaf

Acalypha gracilens, Slender Copperleaf

Acalypha ostryifolia, Hop-hornbeam Copperleaf

Chamaesyce maculata, Spotted Spurge

Chamaesyce nutans, Eyebane

Chamaesyce prostrata, Spotted Spurge

Cnidoscolus texanus, Texas Bull Nettle

Croton capitatus, Woolly Croton

Croton glandulosus, Tropic Croton

Croton lindheimerianus, Three-seed Croton

Croton monanthogynus, One-seed Croton

Croton texensis, Texas Croton

Euphorbia dentata, Toothed Spurge

Euphorbia marginata, Snow-on-the-Mountain

Euphorbia marginata, Snow-on-the-Mountain

Tragia ramosa, Catnip Noseburn

Eysenhardtia texana, Texas Kidneywood

Lupinus texensis, Texas Bluebonnet

Fabaceae—pea Family

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Mimosa aculeaticarpa var. biuncifera, Catclaw Mimosa

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hippocaStanaceae—horSe cheStnut Family

lamiaceae—mint Family

Aesculus glabra var. arguta, Texas Buckeye

Marrubium vulgare, Common Horehound

liliaceae—lily Family

Allium canadense var. fraseri, Canada Wild Onion

Cooperia drummondii, Drummond’s Rain Lily

Cooperia pedunculata, Prairie Rain Lily

meniSpermaceae—moonSeed Family

Nolina texana, Sacahuista

Cocculus carolinus, Carolina Snailseed

Nothoscordum bivalve, Crow Poison

moraceae—mulberry Family

papaveraceae—poppy Family

Morus rubra, Red Mulberry

phytolaccaceae—pokeweed Family

Argemone albiflora, White Prickly Poppy

plantaGinaceae—plantain Family

Phytolacca americana, American Pokeweed

Plantago virginica, Pale-seed Plantain

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polyGonaceae—buckwheat Family

Plantago wrightiana, Wright’s Plantain

Eriogonum annuum, Annual Wild Buckwheat

primulaceae—primroSe Family

Eriogonum tenellum var. ramosissimum, Tall Buckwheat ranunculaceae—buttercup Family

Samolus valerandi ssp. parviflorus, Thin-weed Brookweed

Polygonum punctatum, Dotted Smartweed

roSaceae—roSe Family

Anemone berlandieri, Ten-petal Anemone

Ranunculus pusillus, Weak Buttercup

Crataegus crus-galli, Cockspur Hawthorn

rubiaceae—madder Family

Rubus trivialis, Southern Dewberry

Cephalanthus occidentalis, Common Buttonbush

Galium texense, Texas Bedstraw

Ptelea trifoliata, Common Hoptree

Zanthoxylum hirsutum, Tickle-tongue

rutaceae—rue Family

Richardia tricocca, Prairie Buttonweed

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Salicaceae—willow Family

Sapotaceae—Sapodilla Family

Salix nigra, Black Willow

Sideroxylon lanuginosum, Gum Elastic

Scrophulariaceae—FiGwort Family

Solanaceae—potato Family

Bacopa monnieri, Coastal Water Hyssop

Lindernia dubia var. anagallidea, Clasping False Pimpernel ulmaceae—elm Family

Solanum ptychanthum, American Nightshade

Solanum triquetrum, Texas Nightshade

Celtis laevigata, Sugar Hackberry

urticaceae—nettle Family

Parietaria pensylvanica, Pennsylvania Pellitory

Ulmus crassifolia, Cedar Elm

verbenaceae—verbena Family

Urtica chamaedryoides, Stinging Nettle

vitaceae—Grape Family

Aloysia gratissima, Common Beebush

Phyla nodiflora, Frogfruit

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Vitis mustangensis, Mustang Grape

yellow

aSteraceae—SunFlower Family

(For Ambrosia psilostachya, Western Ragweed, see Berries, Seeds, Pods, and Fruit)

(For Tragopogon dubius, Goatsbeard, see Berries, Seeds, Pods, and Fruit)

Calyptocarpus vialis, Prostrate Lawnflower

Centaurea melitensis, Star Thistle

Coreopsis wrightii, Rock Coreopsis

Coreopsis wrightii, Rock Coreopsis

Croptilon hookerianum var. hookerianum, Hooker’s Scratch Daisy

Croptilon hookerianum var. hookerianum, Hooker’s Scratch Daisy

Engelmannia pinnatifida, Engelmann’s Daisy

Grindelia squarrosa, Curly-cup Gumweed

Gutierrezia texana, Texas Broomweed

Helenium badium, Basin Sneezeweed

Helenium badium, Basin Sneezeweed

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Heterotheca stenophylla, Narrow-leaf Gold Aster

Heterotheca subaxillaris, Camphorweed

Krigia occidentalis, Western Dwarf Dandelion

Lactuca ludoviciana, Western Wild Lettuce

Pseudognaphalium canescens Wright’s Cudweed

Pyrrhopappus pauciflorus, Texas Dandelion

Ratibida columnifera, Mexican Hat

Rudbeckia hirta, Black-eyed Susan

Senecio ampullaceus, Texas Groundsel

Sonchus asper, Prickly Sow Thistle

Taraxacum officinale, Common Dandelion

Thelesperma filifolium, Greenthread

Thymophylla tenuiloba var. tenuiloba, Bristleleaf Dyssodia

Verbesina encelioides, Cowpen Daisy

Wedelia hispida, Hairy Wedelia

Xanthisma texana ssp. drummondii, Texas Sleepy Daisy

berberidaceae—barberry Family

Xanthium strumarium var. canadense (leaves only), Cocklebur

braSSicaceae—muStard Family

Mahonia trifoliolata, Agarito

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cactaceae—cactuS Family

Descurainia pinnata, Western Tansy Mustard

Lesquerella sp., Bladderpod genus

Cylindropuntia leptocaulis, Pencil Cactus

ciStaceae—rockroSe Family

Opuntia engelmannii var. lindheimeri, Texas Prickly Pear

Helianthemum georgianum, Georgia Rockrose

Opuntia macrorhiza, Plains Prickly Pear

cluSiaceae—manGoSteen Family

Hypericum drummondii, Nits-and-Lice

craSSulaceae—Stonecrop Family

Hypericum gentianoides, Orangegrass

Hypericum mutilum, Dwarf St.-John’s-Wort

cucurbitaceae—Gourd Family

Sedum nuttallianum, Yellow Stonecrop

Cucurbita foetidissima, Buffalo Gourd

Fabaceae—pea Family

Ibervillea lindheimeri, Lindheimer’s Globeberry

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Medicago minima, Bur Clover

Prosopis glandulosa, Honey Mesquite

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Rhynchosia senna var. texana, Texas Snoutbean

Senna lindheimeriana, Lindheimer’s Senna

Trifolium campestre, Large Hop Clover

Zornia bracteata, Bracted Zornia

Quercus fusiformis, Plateau Live Oak

Quercus marilandica, Blackjack Oak

Quercus stellata, Post Oak

FaGaceae—beech Family

Fumariaceae—Fumitory Family

lentibulariaceae—bladderwort Family

Corydalis sp., Fumewort genus

linaceae—Flax Family

Utricularia cornuta, Horned Bladderwort

loaSaceae—loaSa Family

Linum hudsonioides, Texas Flax

Mentzelia oligosperma, Stickleaf

malvaceae—mallow Family

Abutilon fruticosum, Indian Mallow

Sida abutifolia, Spreading Sida

Sida lindheimeri, Lindheimer’s Sida

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oleaceae—olive Family

onaGraceae—eveninG primroSe Family

Forestiera pubescens, Elbowbush

Ludwigia peploides, Smooth Water Primrose

oxalidaceae—wood Sorrel Family

paSSiFloraceae—paSSionFlower Family

Oxalis dillenii, Dillen’s Oxalis

Oenothera laciniata, Cut-leaf Evening Primrose

portulacaceae—purSlane Family

Passiflora affinis, Bracted Passionflower

Portulaca oleracea, Common Purslane

ranunculaceae—buttercup Family

Scrophulariaceae—FiGwort Family

Ranunculus macranthus, Large-flower Buttercup

Portulaca umbraticola, Wing-pod Portulaca

Mimulus glabratus, Round-leaf Monkeyflower

Solanaceae—potato Family

Verbascum thapsus, Common Mullein

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Physalis cinerascens var. cinerascens, Beach Groundcherry

Solanum rostratum, Buffalobur Nightshade

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Cacti and Yuccas cacti Texas prickly pear, plains prickly pear, and pencil cactus are common throughout the park in all zones. The various species of prickly pear apparently hybridize quite readily, making identification more challenging. White lace and hedgehog cacti prefer well-drained flanks of granite, especially along small fractures where a thin layer of grus has collected. Clumps of claret-cup cactus can be found in protected areas on the granite flanks. Cacti are at their best in the spring, when impossibly beautiful flowers sprout from their spiny surfaces. Blooming is dependent on the timing of rainfall and may vary considerably from year to year. The first to bloom is the claret-cup cactus in

mid-March. The Texas and plains prickly pears, along with nipple cactus, bloom in April. The white lace cactus blooms in early June with amazing pink flowers. The fruits of the prickly pear are especially attractive; they can be found in the fall. Pencil cactus is particularly insidious. You may become acquainted with it if you hike off-trail without hiking boots, long pants, and thick socks, especially in the mesquite grassland zone. It has an amazing ability to blend into the grass. The plant has an irritant that helpfully reminds you of your close encounter for some time after the spines have been removed.

cactaceae—cactuS Family

Echinocereus reichenbachii ssp. reichenbachii, (mutation) White Lace Cactus

Cylindropuntia leptocaulis, Pencil Cactus

Echinocereus coccineus var. coccineus, Claretcup Cactus

Echinocereus reichenbachii ssp. reichenbachii, White Lace Cactus

Mammillaria heyderi var. heyderi, Nipple Cactus

Opuntia engelmannii var. lindheimeri, Texas Prickly Pear

Opuntia engelmannii var. lindheimeri, Texas Prickly Pear

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Opuntia engelmannii var. lindheimeri (mutation), Texas Prickly Pear

Opuntia macrorhiza, Plains Prickly Pear

Thelocactus setispinus, Hedgehog Cactus

yuccas the white threads coming off the leaves. Although The yucca that you are most likely to see is Buckley’s yucca. This species is quite common through- twisted-leaf yucca is common in the Texas Hill out the park, except directly in creek beds. Look for Country, only one specimen was found at the park.

aGavaceae—aGave Family

Yucca constricta, Buckley’s Yucca

Yucca rupicola, Twisted-leaf Yucca

ferns

Ferns The acidic grus soil at Enchanted Rock SNA creates ideal conditions for a number of fern species. Two of them, the hammock fern and Kaulfuss’ lipfern, are well outside their home ranges in northern Mexico. The granite flank zone supports the greatest diversity of ferns. All of the ferns present in the park can be found here. Some ferns, like the grayish green fairy swords, may be out in the open at the base of a large boulder where grus has accumulated. Others, like the wooly lipfern, prefer more sheltered locations. 174

Two ferns, the blunt-lobed woodsia and the Alabama lipfern, may be found along shaded stream banks where water is frequently present. Interestingly, there are almost no ferns in the wooded areas away from the granite. You will find blunt-lobed woodsia and Alabama lipfern only along sheltered creek banks with regular water. Note: Spike moss, closely related to ferns, is covered in the Spike Mosses, Lichens, Mosses, Liverworts, and Algae section.

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blechnaceae—chain Fern Family

dryopteridaceae—wood Fern Family

Blechnum occidentale, Hammock Fern

Woodsia obtusa, Blunt-lobed Woodsia

pteridaceae—maidenhair Fern Family

Astrolepus sinuata, Wavy Scaly Cloakfern

Cheilanthes alabamensis, Alabama Lipfern

Cheilanthes alabamensis, Alabama Lipfern

Cheilanthes kaulfussii, Kaulfuss’ Lipfern

Cheilanthes kaulfussii, Kaulfuss’ Lipfern

Cheilanthes kaulfussii, Kaulfuss’ Lipfern

Cheilanthes lindheimeri, Fairy Swords

Cheilanthes lindheimeri, Fairy Swords

Cheilanthes tomentosa, Wooly Lipfern

Cheilanthes tomentosa, Wooly Lipfern

Cheilanthes tomentosa, Wooly Lipfern

Cheilanthes tomentosa, Wooly Lipfern

Cheilanthes tomentosa, Wooly Lipfern

Pellaea ovata, Ovate-leaf Cliff Brake Fern

Pellaea wrightiana, Wright’s Cliff Brake Fern

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Grasses, Grasslike Plants, Sedges, and Rushes grasses There are many grasses found at Enchanted Rock SNA. Grasses are a little tricky to identify, because of the number of species that look very much like other species. The best mechanism for identifying grasses is to examine the inflorescence. There

still can be difficulties for the nonexpert, especially with the threeawn, panicum, and lovegrass species. Note that grass-like plants, such as sacahuista and cattail, are included in this section.

Poaceae—Grass Family

Andropogon glomeratus, Bushy Bluestem

Aristida sp., Threeawn genus

Avena fatua, Wild Oat

Bothriochloa ischaemum var. songarica, King Ranch Bluestem

Bothriochloa saccharoides var. torreyana, Silver Bluestem

Bothriochloa saccharoides var. torreyana, Silver Bluestem

Bothriochloa saccharoides var. torreyana, Silver Bluestem

Bouteloua aristidoides, Needle Grama

Bouteloua curtipendula, Sideoats Grama

Bouteloua curtipendula, Sideoats Grama

Bouteloua hirsuta, Hairy Grama

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Bouteloua rigidiseta, Texas Grama

Bromus catharticus, Rescuegrass

Bromus japonicus, Japanese Brome

Buchloe dactyloides, Buffalograss

Cenchrus spinifex, Common Sandbur

Chloris cucullata, Hooded Windmillgrass

Chloris verticillata, Tumble Windmillgrass

Dichanthelium acuminatum var. lindheimeri, Lindheimer’s Panicgrass

Digitaria californica, California Cottontop

Digitaria ciliaris, Southern Crabgrass

Echinochloa colona, Jungle Rice

Elymus canadensis, Canada Wild Rye

Elymus virginicus, Virginia Wild Rye

Eragrostis sp., Lovegrass genus

Eragrostis sp., Lovegrass genus

Eragrostis secundiflora, Red Lovegrass

Eragrostis superba, Wilman’s Lovegrass

Erioneuron pilosum, Hairy Tridens

Heteropogon contortus, Tanglehead

Heteropogon contortus, Tanglehead

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Hordeum pusillum, Little Barley

Leptochloa dubia, Green Sprangletop

Limnodea arkansana, Ozark Grass

Lolium perenne, Perennial Ryegrass

Lolium perenne, Perennial Ryegrass

Melica nitens, Three-flower Melic

Muhlenbergia lindheimeri, Lindheimer’s Muhly

Muhlenbergia lindheimeri, Lindheimer’s Muhly

Nassella leucotricha, Texas Wintergrass

Panicum virgatum, Switchgrass

Paspalum pubiflorum, Hairy Paspalum

Paspalum setaceum, Thin Paspalum

Paspalum urvillei, Vasey Grass

Phalaris caroliniana, Carolina Canarygrass

Polypogon monspeliensis, Annual Rabbit’s Foot Grass

Schizachyrium scoparium, Little Bluestem

Setaria leucopila, Plains Bristlegrass

Setaria parviflora, Knotroot Bristlegrass

Setaria scheelei, Southwestern Bristlegrass

Sorghastrum nutans, Indiangrass

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Sorghastrum nutans, Indiangrass

Sorghum halepense, Johnsongrass

Sporobolus cryptandrus, Sand Dropseed

Steinchisma hians, Gaping Panicum

Tridens albescens, White Tridens

Tridens flavus, Purpletop

Tripogon spicatus, American Tripogon

Tripogon spicatus, American Tripogon

Tripsacum dactyloides, Eastern Gamagrass

Vulpia octoflora, Common Six-weeks Grass

grasslike plants Sacahuista, cattail, and quillwort look somewhat like grasses, but they belong to other families. They are included here for ease of identification. Quillwort typically grows as a monoculture in shallow vernal pools with muddy bottoms. Care should be taken to avoid confusing it with

Canada wild onion, Drummond’s wild garlic, crow poison, American tripogon, or other larger plants. There are two species of quillwort at Enchanted Rock SNA; one, the black-footed quillwort, is endemic to the vernal pools of the Llano Region.

fauna g ras se s, g rassl ik e pl a nts, sedf lgora es, aannddrushes

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iSoetaceae—Quillwort Family

liliaceae—lily Family

Isoetes sp., Quillwort genus

Isoetes sp., Quillwort genus

typhaceae—cattail Family

Nolina texana, Sacahuista

Typha sp., Cattail genus

sedges and rushes Sedge and rush species can be quite difficult to identify, especially from photographs. They occupy

similar habitats, which increases the difficulty of distinguishing some rush species from the sedges.

cyperaceae—SedGe Family

Carex cephalophora, Smallhead Sedge

180

Bulbostylis capillaris, Dense-tuft Hair Sedge

Bulbostylis capillaris, Dense-tuft Hair Sedge

Carex cephalophora, Smallhead Sedge

Carex muhlenbergii, Muhlenberg’s Sedge

Cyperus acuminatus, Taper-leaf Flat Sedge

Cyperus echinatus, Cylinder Flat Sedge

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Cyperus esculentus, Yellow Nut Sedge

Cyperus haspan, Sheathed Flat Sedge

Cyperus odoratus, Fragrant Flat Sedge

Cyperus odoratus, Fragrant Flat Sedge

Cyperus retroflexus, One-flower Flat Sedge

Cyperus retrorsus, Pine Barren Sedge

Cyperus rotundus, Nut Grass

Cyperus squarrosus, Bearded Flat Sedge

Cyperus strigosus, False Nut Grass

Eleocharis obtusa, Blunt Spike Rush

Eleocharis parvula, Dwarf Spike Rush

Eleocharis parvula, Dwarf Spike Rush

Juncaceae—Rush Family

Fuirena simplex, Umbrella Sedge

Schoenoplectus saximontanus, Rocky Mountain Bulrush

Juncus marginatus, Grass-leaf Rush

Juncus torreyi, Torrey’s Rush

Juncus diffusissimus, Slim-pod Rush

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Berries, Seeds, Pods, and Fruit Berries, seeds, pods, and fruit are, like flowers, another useful mechanism for identifying a wide

variety of plants. A few common flower buds prior to opening are also included here.

anacardIaceae—sumac FamIly

Rhus lanceolata, Prairie Flameleaf Sumac

Rhus lanceolata, Prairie Flameleaf Sumac

Rhus virens, Evergreen Sumac

Daucus pusillus, Rattlesnake Weed

Torilis arvensis, Spreading Hedge Parsley

Asclepias asperula, Antelope Horns

Asclepias asperula, Antelope Horns

Matelea reticulata, Net-vein Milkvine

Ambrosia psilostachya, Western Ragweed

Baccharis neglecta, Roosevelt Weed

Cirsium texanum, Texas Thistle

apIaceae—carrot FamIly

Toxicodendron radicans Poison Ivy

asclepIadaceae—mIlkweed FamIly

asteraceae—sunFlower FamIly

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Cirsium texanum, Texas Thistle

Coreopsis wrightii, Rock Coreopsis

Gaillardia pulchella Indian Blanket

Gamochaeta purpurea, Purple Cudweed

Grindelia squarrosa, Curly-cup Gumweed

Helenium badium, Basin Sneezeweed

Krigia occidentalis, Western Dwarf Dandelion

Lygodesmia texana, Texas Skeleton Plant

Pseudognaphalium canescens, Wright’s Cudweed

Pyrrhopappus pauciflorus, Texas Dandelion

Ratibida columnifera, Mexican Hat

Senecio ampullaceus, Texas Groundsel

BerBerIdaceae—BarBerry FamIly

Taraxacum officinale, Common Dandelion

Tragopogon dubius, Goatsbeard

Xanthium strumarium var. canadense, Cocklebur BrassIcaceae—mustard FamIly

(For Descurainia pinnata, Western Tansy Mustard, see Flowers, Yellow; for Draba platycarpa, Broadpod Draba, see Flowers, White)

Mahonia trifoliolata, Agarito

Mahonia trifoliolata, Agarito

Arabis petiolaris, Brazos Rock Cress

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Arabis petiolaris, Brazos Rock Cress

Capsella bursa-pastoris, Shepherd’s Purse

Lepidium virginicum, Virginia Peppergrass

Lesquerella sp., Bladderpod genus

Mammillaria heyderi var. heyderi, Nipple Cactus

Opuntia engelmannii var. lindheimeri, Texas Prickly Pear

Opuntia macrorhiza, Plains Prickly Pear

cactaceae—cactI FamIly

For Cylindropuntia leptocaulis, Pencil Cactus, see Cacti)

caryophyllaceae—pInk FamIly

cucurBItaceae—gourd FamIly

Silene antirrhina, Sleepy Catchfly

Cucurbita foetidissima, Buffalo Gourd

cupressaceae—cypress FamIly

Cyclanthera dissecta, Bur Cucumber

Juniperus ashei, Ashe Juniper

Ibervillea lindheimeri, Lindheimer’s Globeberry

eBenaceae—eBony FamIly

euphorBIaceae—spurge FamIly

(For Euphorbia dentata, Toothed Spurge, see Flowers, White)

Diospyros texana, Texas Persimmon

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Chamaesyce sp., Spurge genus

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Cnidoscolus texanus, Texas Bull Nettle

Cnidoscolus texanus, Texas Bull Nettle

Croton monanthogynus, One-seed Croton

Euphorbia marginata, Snow-on-the-Mountain

Astragalus nuttallianus var. austrinus, Smallflower Milk Vetch

Dalea nana, Dwarf Nana

Eysenhardtia texana, Texas Kidneywood

Lupinus texensis, Texas Bluebonnet

Medicago minima, Bur Clover

Mimosa aculeaticarpa var. biuncifera, Catclaw Mimosa

Prosopis glandulosa, Honey Mesquite

Senna lindheimeriana, Lindheimer’s Senna

Senna lindheimeriana, Lindheimer’s Senna

Strophostyles helvola, Amberique Bean

Strophostyles helvola, Amberique Bean

Quercus fusiformis, Plateau Live Oak

Quercus marilandica, Blackjack Oak

FaBaceae—pea FamIly

(For Rhynchosia senna var. texana, Texas Snoutbean, see Flowers, Yellow) (For Styphnolobium affine, Eve’s Necklace, see Trees, Shrubs, and Vines)

Fagaceae—Beech FamIly

(For Quercus fusiformis, Plateau Live Oak, see Trees, Shrubs, and Vines)

Vicia ludoviciana, Deer Pea Vetch

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hIppocastanaceae—horse chestnut FamIly

Quercus stellata, Post Oak

Aesculus glabra var. arguta, Texas Buckeye

Juglandaceae—walnut FamIly

Aesculus glabra var. arguta, Texas Buckeye

lIlIaceae—lIly FamIly

Carya illinoinensis, Pecan

Carya texana, Texas Hickory

menIspermaceae—moonseed FamIly

Allium canadense var. fraseri, Canada Wild Onion

Allium canadense var. fraseri, Canada Wild Onion

Cooperia pedunculata, Prairie Rain Lily

moraceae—mulBerry FamIly

Cocculus carolinus, Carolina Snailseed

oleaceae—olIve FamIly

Morus rubra, Red Mulberry

passIFloraceae—passIonFlower FamIly

Forestiera pubescens, Elbowbush

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Fraxinus pennsylvanica, Green Ash

Passiflora affinis, Bracted Passionflower

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phytolaccaceae—pokeweed FamIly

polygonaceae—Buckwheat FamIly

Phytolacca americana, American Pokeweed

portulacaceae—purslane FamIly

Rumex hastatulus, Heart-wing Sorrel

prImulaceae—prImrose FamIly

Portulaca pilosa, Shaggy Portulaca

Samolus valerandi ssp. parviflorus, Thin-weed Brookweed

ranunculaceae—Buttercup FamIly

Anemone berlandieri, Ten-petal Anemone

Clematis pitcheri, Leatherflower

Clematis pitcheri, Leatherflower

Malus sp., Crabapple genus

Prunus persica, Peach

Rubus trivialis, Southern Dewberry

rosaceae—rose FamIly

ruBIaceae—madder FamIly

rutaceae—rue FamIly

Cephalanthus occidentalis, Common Buttonbush

Zanthoxylum hirsutum, Tickle-tongue

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salIcaceae—wIllow FamIly

sapIndaceae—soapBerry FamIly

Populus deltoides, Eastern Cottonwood

Salix nigra, Black Willow

sapotaceae—sapodIlla FamIly

Ungnadia speciosa, Mexican Buckeye

smIlacaceae—catBrIer FamIly

Sideroxylon lanuginosum, Gum Elastic

solanaceae—potato FamIly

Smilax bona-nox, Saw Greenbrier

Solanum elaeagnifolium, Silverleaf Nightshade

Solanum elaeagnifolium, Silverleaf Nightshade

Physalis cinerascens var. cinerascens, Beach Groundcherry

Solanum dimidiatum, Western Horse Nettle

Solanum ptychanthum, American Nightshade

Solanum ptychanthum, American Nightshade

styracaceae—storax FamIly

typhaceae—cattaIl FamIly

(For Hermannia texana, Mexican Mallow, see Flowers, Red)

Solanum rostratum, Buffalobur Nightshade

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Solanum triquetrum, Texas Nightshade

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ulmaceae—elm FamIly

Typha sp., Cattail genus

Celtis laevigata, Sugar Hackberry

Celtis laevigata, Sugar Hackberry

verBenaceae—verBena FamIly

Celtis laevigata var. reticulata, Netleaf Hackberry

Celtis laevigata var. reticulata, Netleaf Hackberry

Ulmus crassifolia, Cedar Elm

vItaceae—grape FamIly

Lantana urticoides, Texas Lantana

Parthenocissus quinquefolia, Virginia Creeper

Vitis mustangensis, Mustang Grape

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Other Plants Botanists would not group this wide variety of plants together. They are collected here as they do not easily fit into the other categories.

spike mosses Spike moss is most typically found in and around (wet) granite boulders in the granite flank zone or granite top zone near vernal pools. The plants

Selaginella arenicola ssp. riddellii, Riddell’s Spike Moss

are very low-growing, and they go dormant in dry conditions. Spike mosses are related to ferns.

Selaginella wrightii, Wright’s Spike Moss

ball moss and mistletoe Ball moss is not a moss at all but instead is a type of flowering plant. Look for it in trees, particularly cedar elm and plateau live oak. Mistletoe is also a

BromelIaceae—BromelIad FamIly

flowering plant, found frequently in honey mesquite trees.

vIscaceae—mIstletoe FamIly

Tillandsia recurvata, Ball Moss

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Phoradendron tomentosum, Mistletoe

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lichens Lichen is formed by a symbiotic relationship between a fungi and a partner, either an alga or a cyanobacterium. The alga or bacterium produces food for the fungus. The fungus provides water, minerals, and shelter for the alga. Lichen species grow on rocks, but they can also grow on trees, concrete, and other substrates. Often, a species is particular about its host, preferring granite over limestone, wood over concrete, twigs over the trunk, and so on. The presence of lichen accelerates weathering of granite in two ways. First, the lichen forms carbon

dioxide, which helps accelerate chemical weathering. Second, the thalloid tissue in the lichen swells when moisture is present, leading to mechanical weathering. Lichens are categorized into three, four, or more forms, depending on the researcher. The four commonly recognized forms are crustose (crustlike or flat), foliose (leaflike), fruticose (stalked or branched), and squamulose (scalelike). The crustose form typically manifests itself as a grouping of small round polyps that are firmly attached, usually to rock.

Mosaic of Lichens

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Crustose lichens come in a wide variety of colors, including red, orange, yellow, green, black, and others. These lichens are sometimes subdivided by form into leprose, areolate, rimrose, lobed, and other categories.

Crustose Lichen

Crustose Lichen

Foliose Lichen

Foliose Lichen

Usnea sp., Fruticose Lichen

Telochistes sp., Fruticose Lichen

Foliose lichens appear to have small leaves. They often grow as an expanding circle, with some species growing one centimeter per year. Large foliose lichens are quite old. Lobed crustose lichens are very similar in appearance to foliose or some squamulose lichens.

Fruticose lichens have stemlike structures. One common species grows in cedar elm trees at the park.

Squamulose lichens have the appearance of a cross between crustose and foliose lichens.

Squamulose Lichen

The vast majority of lichens on the granite at Enchanted Rock SNA are in the crustose form, including most of the yellow, green, orange, gray, and white lichen species. Foliose lichen is also common. Although it would have been interesting to include a photographic record of the lichens at Enchanted Rock SNA, it is difficult for the nonexpert

to identify individual species of lichens. In fact, close examination of the spores and chemical analysis are required to establish the species definitively for most specimens, especially since the lichens at Enchanted Rock SNA have never been systematically studied. As collection of specimens was not part of this work, the species remain unidentified for future researchers.

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mosses Green, verdant moss grows in shaded, protected, moist areas around granite boulders and along creek beds.

Green Moss

Grimmia laevigata, Dry Rock Moss

Polytrichaceae, Moss family

Green Moss

liverworts Liverworts are found growing out of permanent or semipermanent water along Sandy Creek and Walnut Springs Creek. Riccia sp., Liverwort genus

algae Algae are most commonly found where pools of creek water are drying up, leaving behind mats of the stuff until the pond dries up completely.

Zygnemataceae—FIlamentous green algae FamIly

Spiragyra sp., Green alga genus

Spiragyra sp., Green alga genus

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mushrooms and other fungi Mushrooms are somewhat difficult to identify without close examination of the specimen. Some

representative specimens are illustrated, but no detailed list of the specimens present was created.

Mosaic of Fungi

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Animals (Except Bugs)

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Mammals Mammals are found throughout the park, but they are not as easy to find as one might expect. Most mammals are nocturnal, so observers have to be out at dusk or dawn to catch a glimpse of them. It is typically too dark away from the campground to see mammals in the dead of night, unless the moon is nearly full or flashlights are available. One mammal that is definitely easy to find is the white-tailed deer. Anytime around dawn or dusk near picnic areas or campgrounds, deer can be located. There are alarming numbers of deer at the park and in Central Texas, as their natural enemies are no longer present to keep a check on their populations. Hunting is allowed for a couple of weeks in the winter at Enchanted Rock SNA to cull the deer population. Some exotic deer species have been introduced in the area as well. Although none were spotted at the park, they were seen nearby. Remember that the deer are wild animals, and if you approach them too closely, you may find out how powerful their hooves are. The ubiquitous eastern fox squirrels (the grayish squirrels) can be found anywhere there are tall trees. The park’s picnic and camping areas are good places to find them. Rock squirrels are harder to locate. See if you can find them on the flanks of granite domes, especially where large boulders provide protection for them. They appear to be especially active in the fall and spring, but less so in the summer and not at all in the winter. It is highly unlikely that you will encounter coyotes at the park, but you have a good chance of cervIdae—true deer FamIly

hearing them or spotting their scat. Listen for their howls, especially around sunset. Nine-banded armadillos, which are not common at the park, use an interesting technique to forage for insects. An armadillo will push its body under a mat of tall grass, then bolt about under the grass, making a fair amount of racket with its movements and associated soft grunting sounds. If you are camping, you may wonder what all that noise is near your tent. They leave small holes in the ground as evidence of their nighttime work. Little creatures like mice and rats are present in the park but not commonly spotted, unless you leave a pack with food in it unattended on the ground. Skunks and raccoons work the campground for food after dusk. Keep food locked in your car. Raccoons can open some coolers, too. Red foxes are occasionally encountered and can be spotted if you are quiet. Eastern cottontail rabbits can be flushed out of their daytime hiding places. Various species of bats come out from their caves and shelters at dusk in the summertime. They are most easily seen from the parking lot of the picnic area or campground as the sky gets dark. In the course of preparing this book, I saw many mammals that I was unable to capture in photographs. Photographing mammals involves the study of their habits in the field, using blinds and other techniques that were not practical for this project. The unphotographed animals include the red fox, striped skunk, black-tailed jackrabbit, Virginia opossum, porcupine, raccoon, and unidentified species of bats. dasypodIdae—armadIllo FamIly

Odocoileus virginianus, White-tailed Deer

Dasypus novemcinctus, Nine-banded Armadillo

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FelIdae—cat FamIly

leporIdae—raBBIt FamIly

Felis domesticus, Domesticated Cat

molossIdae—Free-taIled Bat FamIly

Sylvilagus floridanus, Eastern Cottontail

procyonIdae—raccoon and rIngtaIl FamIly

Tadarida brasiliensis, Brazilian Free-tailed Bat

Procyon lotor, Raccoon

scIurIdae—sQuIrrel FamIly

Sciurus niger, Eastern Fox Squirrel

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Spermophilus variegatus, Rock Squirrel

Spermophilus variegatus, Rock Squirrel

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Birds Central Texas supports a wide variety of birds. No less than 419 species of birds have been verifiably spotted in the Edwards Plateau area, including at least 170 in and around Enchanted Rock SNA. The actual number of species that could be seen at Enchanted Rock SNA is likely much greater. Enchanted Rock SNA is along one of the primary flyways to more southern areas. Additionally, many birds overwinter in Central Texas. Therefore, many birds may be common in one season but not present at all in others. Before sunrise on a spring morning, birdsong fills the campground. The cacophony may get you out of your tent early to check on the commotion. If the day is overcast and gloomy, the birds may sing throughout the day. The most common birds you will see are black and turkey vultures. On any given day, you can find dozens of the birds riding the thermals as air temperature rises during the day. Near sunset they land en masse on granite outcrops. One good location to see lots of vultures is on the northwest side of Enchanted Rock Dome near sunset. At times, especially in the mornings, you may find an occasional hawk flying with the vultures. Although you probably will not see owls, you

may hear them, especially after sunset and before sunrise around the main campground. A number of screech owls and great horned owls live in the area. Mockingbirds, cardinals, canyon wrens, blackchinned hummingbirds, ladder-backed woodpeckers, and chipping sparrows are all common. The flashiest bird is the painted bunting, which can be found in the grasses near water in the summer. Look for hummingbirds feeding on purple leatherflower, Lindheimer’s prickly pear, and other flowers, depending on the season. Get out with your binoculars, spotting scope, or telephoto lens and see what you can find. Focus your efforts along Sandy Creek in the early morning, where the diversity of trees and shrubs maximizes the number of birds you may find, but don’t exclude other areas, as many birds specialize in their preferred habitat. A dedicated birder, especially one familiar with birdsong, should easily be able to identify more than the minimal list of birds photographed here. One group visiting in May 2008 spotted or heard 51 species, many of which are not included in this section, in just two days. The number was thought to be on the low side of what was possible. Birds are sorted by order, then family, then species name.

Turkey vultures fly over Enchanted Rock Dome.

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Anseriformes Order

Ciconiiformes Order

anatIdae—swan, goose, and duck FamIly

cathartIdae—amerIcan vulture FamIly

Cathartes aura, Turkey Vulture

Coragyps atratus, Black Vulture

Falconiformes Order

Charadriiformes Order

accIpItrIdae—Falcon and caracara FamIly

Dendrocygna autumnalis, Black-bellied Whistling Duck

charadrIIdae—plover FamIly

Buteo jamaicensis, Red-tailed Hawk

Columbiformes Order columBIdae—pIgeon and dove FamIly

Charadrius vociferus, Killdeer

Columbina inca, Inca Dove

Cuculiformes Order

Strigiformes Order

cuculIdae—cuckoo and anI FamIly

Columbina passerina, Common Ground Dove

strIgIdae—owl FamIly

Geococcyx californianus, Greater Road Runner

Megascops asio, Eastern Screech Owl

Trochiliformes Order trochIlIdae—hummIngBIrd FamIly

Archilochus alexandri (male), Black-chinned Hummingbird

Archilochus alexandri, Black-chinned Hummingbird

Archilochus alexandri, Black-chinned Hummingbird

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Piciformes Order pIcIdae—woodpecker FamIly

Archilochus alexandri (female) Black-chinned Hummingbird

Picoides scalaris (male), Ladder-backed Woodpecker

Picoides scalaris (female), Ladder-backed Woodpecker

Cardinalis cardinalis (male), Northern Cardinal

Cardinalis cardinalis (female) Northern Cardinal

Passerina ciris (male), Painted Bunting

Piranga rubra (male), Summer Tanager

Piranga rubra, Summer Tanager

Aimophila ruficeps, Rufous-crowned Sparrow

Chondestes grammacus, Lark Sparrow

Melospiza lincolnii, Lincoln’s Sparrow

Passerculus sandwichensis, Savannah Sparrow

Pipilo erythrophthalmus, Rufous-sided Towhee

Spizella passerina, Chipping Sparrow

Passeriformes Order cardInalIdae—cardInal FamIly

Sphyrapicus varius, Yellow-bellied Sapsucker

Passerina ciris (female), Painted Bunting

emBerIZIdae—warBler and sparrow FamIly

Melospiza melodia, Song Sparrow

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FrIngIllIdae—FInch FamIly

Spizella pusilla, Field Sparrow

Carduelis pinus, Pine Siskin

Carduelis tristis, American Finch

Icterus spurius, Orchard Oriole

Sturnella magna (or S. neglecta), Eastern Meadowlark

IcterIdae—BlackBIrd and orIole FamIly

Icterus spurius, Orchard Oriole

hIrundInIdae—swallow FamIly

mImIdae—mImIc thrush FamIly

Hirundo fulva, Cave Swallow

parIdae—tItmouse and chIckadee FamIly

Mimus polyglottos, Northern Mockingbird

polIoptIlIdae—gnatcatcher FamIly

Parus atricristatus, Black-crested Titmouse

Polioptila caerulea, Blue-gray Gnatcatcher

troglodytIdae—wren FamIly

Catherpes mexicanus (male), Canyon Wren

Catherpes mexicanus (female) Canyon Wren

Salpinctes obsoletus, Rock Wren

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tyrannIdae—Flycatcher FamIly

Thryomanes bewickii, Bewick’s Wren

Empidonax traillii, Willow Flycatcher

Sayornis phoebe, Eastern Phoebe

Myiarchus cinerascens, Ash-throated Flycatcher

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Reptiles, Amphibians, and Water Creatures Reptiles include lizards and whiptails, skinks, snakes, turtles, salamanders, and newts. The easiest reptiles to find at Enchanted Rock SNA are lizards,

if the day is warm. Spotting the other reptiles may take a little more effort and planning, or a little bit of luck.

lizards and whiptails It takes warm to hot temperatures to get the lizards active. Being cold-blooded, lizards (and other reptiles) hide during cold weather. Come late March, the lizards come out to play. Look around granite boulders and outcrops for tree, greater earless, Texas spotted whiptail, and Texas spiny lizards. Another good place to find lizards is along Sandy Creek, especially where there are larger boulders or crotaphytIdae—collared and leopard lIZard FamIly

granite outcrops nearby. Nocturnal Mediterranean geckos loiter around the campground restroom. If you surprise a lizard and it runs off, try holding still and see if it peeks back around a corner at you. They often run away and perch on top of a rock, keeping an eye on a person’s movements and intentions. Many lizards seem quite curious and may even charge toward you in the springtime. gekkonIdae—gecko lIZard FamIly

Crotaphytus collaris, Eastern Collared Lizard

Hemidactylus turcicus, Mediterranean Gecko

phrynosomatIdae—earless, spIny, tree, sIde-Blotched, horned lIZard FamIly

Sceloporus olivaceus, Texas Spiny Lizard

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Cophosaurus texanus, Greater Earless Lizard

Cophosaurus texanus, Greater Earless Lizard

Cophosaurus texanus, Greater Earless Lizard

Sceloporus poinsettii, Crevice Spiny Lizard

Urosaurus ornatus, Tree Lizard

Urosaurus ornatus, Tree Lizard

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teIIdae—whIptaIl lIZard FamIly

Cnemidophorus gularis, Texas Spotted Whiptail

snakes Snakes become active a little later than lizards. It isn’t until late May, when temperatures begin to warm, that park visitors start to encounter lots of snakes. One good place to find many species of snakes is near larger areas of water. Frog Pond and some parts of Sandy Creek support a good crop of plain-bellied water snakes and western ribbon snakes. Both of these snakes are active in the daytime. You are highly unlikely to encounter snakes near the top of a granite dome. The granite flanks and sheltered climbing areas may produce better results.

There are at least four poisonous snakes that may be present at the park. If you do not know your snakes, don’t mess with them. Keep your distance, observe their behavior, take photos, and move on. In general, rattlesnakes are not a common sight, even if you are looking for them. Western diamond-backed rattlesnakes appreciate pencil cactus thickets in the mesquite grassland areas and little rock nooks created by granite boulders. If you are lucky, you may find a rare coral snake along Sandy Creek.

coluBrIdae—coluBrId snake FamIly

elapIdae—coral snake FamIly

Nerodia erythrogaster, Plain-bellied Water Snake

Thamnophis proximus proximus Western Ribbon Snake

vIperIdae—pIt vIpers and vIpers FamIly

Micrurus tener, Texas Coral Snake

Crotalus atrox, Western Diamond-backed Rattlesnake

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turtles, salamanders, skinks, and newts No skinks, salamanders, or newts were encounthor’s first year of visiting the park, no turtles were tered at the park during the research for this book, encountered. In 2007, however, unidentified turtles although many species are in range. In 2006, the au- set up residence at Frog Pond and Moss Lake.

amphibians Little Blanchard’s cricket frogs can be found yearround, except when it is too cold for their metabolism to function. Anywhere there is a little puddle, these cricket frogs may gather, even near small pools of water such as vernal pools on the flanks of the granite domes. They are known as cricket frogs because of the chirping sound they make, more a combination of a cicada and cricket than a croak. By mid-April, tadpoles fill the pools along creeks, even in some of the vernal pools on the domes. Tadpoles, which you can distinguish from fish by the way they waddle when they swim and burrow in the sediment when frightened, go through a metamorphosis, transforming into frogs or toads. The largest tadpoles will transform into Rio Grande leopard frogs. Smaller ones are less mature leopard frog or cricket frog tadpoles. Frog season is somewhat dependent on rainfall, but typically it peaks in mid-June, when a wet Sandy Creek becomes Frog City and leopard frogs are everywhere. A prime spot may have a couple of dozen frogs hopping around. At one point, I

counted thirteen frogs within ten feet of one another holding perfectly still, daring me to find them. Another fifteen or so had hopped for cover. Frogs seem to have a few strategies to escape from enemies. In one strategy, frogs make for the bottom of a nearby pond and hide in the muck or vegetation. Another sees them cross the waterway and head for the grass-covered shoreline on the opposite bank. In a third, they hold completely still, blending in with the grass or rocks near the water. The fourth, used frequently by small cricket frogs, is to enter the water but immediately come back to shore on the same bank (maybe to avoid being eaten by a fish). Several examples of the frogs are included, as individuals of a single species may display a great variety of looks. Toads were quite difficult to find at the park. One possible reason for this may be the drought in 2006, which left little water in the area. Because toads hide during the daytime, they are also harder to find than frogs.

hylIdae—tree Frog FamIly

Acris crepitans blanchardi, Blanchard’s Cricket Frog

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Acris crepitans blanchardi, Blanchard’s Cricket Frog

Acris crepitans blanchardi, Blanchard’s Cricket Frog

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ranIdae—true Frog FamIly

Acris crepitans blanchardi, Blanchard’s Cricket Frog

Acris crepitans blanchardi, Blanchard’s Cricket Frog

Acris crepitans blanchardi, Blanchard’s Cricket Frog, transforming

Rana berlandieri, Rio Grande Leopard Frog

Rana berlandieri, Rio Grande Leopard Frog

Rana berlandieri, Rio Grande Leopard Frog

Rana berlandieri, Rio Grande Leopard Frog tadpole

BuFonIdae—toad FamIly

Bufo woodhousii woodhousii, Woodhouse’s Toad

fish and other water creatures The most fascinating water creatures found at Enchanted Rock SNA are fairy shrimp, which live in the vernal pools atop granite domes. Small crustaceans 1/2" to 1 1/2" in length, fairy shrimp belong to the genus Branchinecta. They may dart, float, or sit on the bottom of a pool, swimming upside down as they move. Fairy shrimp lay two types of eggs. A soft egg requires water until it hatches; a hard egg settles in mud or gravel and can survive extended dry conditions, such as those found at Enchanted Rock SNA, or through the winter. Once hatched, fairy shrimp complete one life cycle in as little as

sixteen days. Most medium to large vernal pools will last a few weeks after a heavy rainfall. The greatest threat to fairy shrimp is from people and dogs that disturb the grus at the bottom of their weathering pits. They are very small and were not photographed. Many species of fish live in Sandy Creek and Walnut Springs Creek. If the creeks are not flowing, the fish congregate in the remaining pools of water, where the remaining fish get fewer and larger. Fish that become stranded die if the water dries up completely, and you can find their bones in the dry

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streambed. Both Sandy Creek and Walnut Springs Creek have springs that create places of last resort during droughts for those fish that are fortunate enough to find their way to the spring-fed areas.

Crayfish can be found in creek beds, where they work the bottom of a pool of water, sparring with each other and in general providing entertainment for the patient observer.

Pool of Stranded Fish

Catfish

Bass

Crayfish

Snail Shell

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Bugs (Including Arachnids)

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Butterflies As with birds, Central Texas supports a wide variety of butterflies and moths. Many subtropical species are at their northern limit in Central Texas. The unique plants within the Llano Region support additional butterflies and moths. This all adds up to more than 80 species of butterflies with verified sightings in Llano, Gillespie, and Mason counties. Butterflies can be found year-round at Enchanted Rock SNA. In the wintertime, the few remaining scratch daisies, shepherd’s purse, and other small cool-weather flowers at isolated locations support a small community of dainty sulphurs, sleepy sulphurs, checkered whites, common buckeyes, and variegated fritillaries. Once the Texas buckeyes and other trees bloom in March, the butterfly (and moth) populations increase dramatically. Following close behind the buds are hoards of munching and chewing caterpillars. If you stand under a live oak tree in late March, you can actually hear the chewing and moving, along with the subtle noise of something small continually falling to the ground, like a very light rain; that’s the droppings of thousands of caterpillars eating fresh live oak leaves. Maybe an umbrella would be appropriate. By April, a rich diversity of butterflies is present. Plants such as the Mexican buckeye, Canada wild onion, and others support communities of black and pipevine swallowtails, common buckeyes,

dainty, orange, and dogface sulphurs, red admirals, checkered whites, question marks, monarchs, queens, gulf fritillaries, various skippers, and many others. Although the butterfly population thins in the summer, the remaining butterflies visit Texas thistle, snow-on-the-mountain, buttonbush, and other flowers. Normally tropical species, such as leafwing butterflies, are sometimes present in the heat of the summer. In the fall through midNovember, butterflies concentrate where cowpen daisy, scratch daisy, and shrubby boneset grow. At the same time, look for California sister flying in and around oak trees. Grasses such as tanglehead grass attract snout butterflies. Central Texas is located on the flyway for monarch butterflies making their way to their winter grounds in northern Mexico. Monarchs from the Midwest head south in the fall, ahead of strong cold fronts. In some years, you can find masses of them at Enchanted Rock SNA in mid-October. The reverse migration takes place in the spring but is less concentrated in flyways and is spread out over time. Butterflies are grouped first by general color, then sorted by species name. Some butterflies appear in more than one color group, either because of differences between the genders or because the upper and lower wing surfaces are different. Unfortunately, the caterpillars for the butterflies and moths could not be included here.

Monarch Butterfly Flyway: Monarch butterflies stop at Enchanted Rock SNA as they travel to Mexico in October. Other flyways have also been identified.

Monarchs on Flowers: Monarch butterflies make their way through the Enchanted Rock SNA area in October ahead of the first strong cold fronts of the fall on their way to foverwinter l ora ainnMexico. d fauna 211

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black/brown/gray/tan/blue

Achalarus casica, Desert Cloudywing

Achalarus casica, Desert Cloudywing

Anaea andria, Goatweed Leafwing

Atlides halesus, Great Purple Hairstreak

Battus philenor (male), Pipevine Swallowtail

Battus philenor (female), Pipevine Swallowtail

Brephidium exilis (female), Western Pygmy Blue

Brephidium exilis, Western Pygmy Blue

Callophrys gryneus, Juniper Hairstreak

Callophrys henrici, Henry’s Elfin

Cercyonis pegala, Common Wood Nymph

Erynnis funeralis, Funereal Duskywing

Erynnis horatius, Horace’s Duskywing

Erynnis horatius, Horace’s Duskywing

Euphyes vestris, Dun Skipper

Euphyes vestris, Dun Skipper

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Hemiargus isola (female), Reakirt’s Blue

Hemiargus isola, Reakirt’s Blue

Hemiargus isola (male), Reakirt’s Blue

Hemiargus isola, Reakirt’s Blue

Lerodea eufala, Eufala Skipper

Limenitis arthemis, Red-spotted Purple

Megathymus yuccae, Yucca Giant Skipper

Megisto rubricate, Red Satyr

Nymphalis antiopa, Mourning Cloak

Papilio cresphontes, Giant Swallowtail

Papilo polyxenes, Eastern Black Swallowtail

Polygonia interrogationis, Question Mark

Satyrium favonius, Southern Hairstreak

Strymon melinus, Gray Hairstreak

Strymon melinus, Gray Hairstreak

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yellow to orange

Abaeis nicippe, Sleepy Orange

Abaeis nicippe, Sleepy Orange

Abaeis nicippe, Sleepy Orange

Atalopedes campestris, Sachem

Atalopedes campestris, Sachem

Colias eurytheme, Orange Sulphur

Colias eurytheme, Orange Sulphur

Copaeodes aurantiaca, Orange Skipperling

Copaeodes aurantiaca, Orange Skipperling

Hylephila phyleus, Fiery Skipper

Hylephila phyleus, Fiery Skipper

Kricogonia lyside, Lyside Sulphur

Mestra amymone, Common Mestra

Nathalis iole, Dainty Sulphur

Nathalis iole, Dainty Sulphur

Papilio cresphontes, Giant Swallowtail

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Phoebis agarithe, Large Orange Sulphur

Pyrisitia lisa, Little Yellow

Zerene cesonia, Southern Dogface

Zerene cesonia, Southern Dogface

white

Anthocharis midea, Falcate Orangetip

Colias eurytheme, Orange Sulphur

Mestra amymone, Common Mestra

Pontia protodice, Checkered White

Pontia protodice, Checkered White

Pyrgus communis, Common Checkered Skipper

Pontia protodice, Checkered White

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red/orange/brown/patterned

Adelpha bredowii eulalia, Arizona Sister

Adelpha bredowii eulalia, Arizona Sister

Agraulis vanillae, Gulf Fritillary

Agraulis vanillae, Gulf Fritillary

Anaea andria, Goatweed Leafwing

Anaea troglodyta, Tropical Leafwing

Anthanassa texana, Texan Crescent

Asterocampa celtis, Hackberry Emperor

Asterocampa leilia, Empress Leilia (possibly A. celtis)

Chlosyne lacinia, Bordered Patch

Danaus gilippus, Queen

Danaus gilippus, Queen

Danaus plexippus, Monarch

Euptoieta claudia, Variegated Fritillary

Euptoieta claudia, Variegated Fritillary

Hesperia viridis, Green Skipper

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Junonia coenia, Common Buckeye

Junonia coenia, Common Buckeye

Libytheana carinenta, American Snout

Libytheana carinenta, American Snout

Limenitis archippus, Viceroy

Limenitis archippus, Viceroy

Megisto rubricate, Red Satyr

Nymphalis antiopa, Mourning Cloak

Phyciodes graphica, Graphic Crescent

Phyciodes graphica, Graphic Crescent

Phyciodes phaon, Phaon Crescent

Phyciodes phaon, Phaon Crescent

Polygonia interrogationis, Question Mark

Pyrgus communis, Common Checkered Skipper

Vanessa atalanta, Red Admiral

Vanessa atalanta, Red Admiral

Vanessa cardui, Painted Lady

Vanessa cardui, Painted Lady

Vanessa virginiensis, American Lady

Vanessa virginiensis, American Lady

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Moths Moths have not been surveyed, and the number of species present at Enchanted Rock SNA has not been determined. Many moth species are quite difficult to identify, as many of them look quite similar. The best resources to assist with moth identifications are online Web sites or a moth expert. As moths are typically nocturnal, they can be difficult to find in the daylight. Good places to see moths are around the restrooms in the campground or at the visitor center on a warm spring or summer evening. (Yes, that was me taking photographs of moths around the restroom windows well after dark.) In the daytime, moths hide on

trees (and walls) waiting for nighttime. You may also want to take note of flowers frequented by butterflies during the daytime and, using a flashlight, see what kinds of moths are feeding on them at night. In general, more observations will continue to generate many more species. This list is probably only scratching the surface of what is present at the park. Moths are sorted by Hodges number and then within their taxonomic families. The Hodges number originated from a detailed study of Lepidoptera by R. W. Hodges in 1983. A new numbering system is under development.

ELACHISTIDAE—GRASS MINER MOTH FAMILY (0855–1075)

COSSIDAE—CARPENTER AND LEOPARD MOTH FAMILY (2627–2700)

Ethmia semilugens, 0976

Ethmia apicipunctella, 0978

TORTRICIDAE—TORTRICID (LEAF ROLLER) MOTH FAMILY (2701–3863)

Givira theodori, 2662

Cudonigera houstonana, 3647, Juniper Budworm Moth LIMACODIDAE—SLUG CATERPILLAR MOTH FAMILY (4651–4702)

Sparganothis pettitana, 3719, Vine Leafroller Tortrix Moth

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Sparganothis sp., 3695–3731

CRAMBIDAE—CRAMBID SNOUT MOTH FAMILY (4703–5509)

Euclea delphinii, 4697, Spiny Oak Slug Moth

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Petrophila jaliscalis, 4775

Eustixia pupula, 4794, Spotted Peppergrass Moth

Uresiphita reversalis, 4992

Pyrausta tyralis, 5069, Coffee-loving Pyrausta Moth

Udea rubigalis, 5079, Celery Leaftier Moth

Samea baccatalis, 5152, Baccatalis Moth

Desmia funeralis, 5159, Grape Leafroller

Nomophila nearctica, 5156, Lucerne Moth

PYRALIDAE—PYRALID MOTH FAMILY (5510–6075)

Diathrausta harlequinalis, 5175, Harlequin Webworm Moth

Diastictis fracturalis, 5256, Diastictus Moth

Urola nivalis, 5464

PTEROPHORIDAE—PLUME MOTH FAMILY (6089–6234)

Parachma ochracealis, 5538, Parachma Moth

Galasa nigrinodis, 5552, Boxwood Leaftier

Pterophoridae, 6089–6234, Plume Moth

GEOMETROIDEA—GEOMETRID SUPERFAMILY (6256–7662)

Digrammia irrorata, 6395, Many-spotted Angle Moth

Digrammia cyda, 6415

Digrammia cyda, 6415

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Econista dislocaria, 6419

Glena quinquelinearia, 6454

Exelis ophiurus, 6480

Anacamptodes dataria, 6573

Iridopsis defectaria, 6586, Brown-shaded Gray Moth

Anavitrinella pampinaria, 6590, Common Gray Moth

Phigalia titea, 6658, Half Wing Moth

Paleacrita vernata, 6662, Spring Cankerworm

Euchlaena tigrinaria, 6737, Mottled Euchlaena Moth

Pero sp., 6752–6763, Pero Moth genus

Prochoerodes transversata, 6982, Large Maple Spanworm

Nematocampa resistaria, 7009, Horned Spanworm Moth

Nemoria zygotaria, 7040

Nemoria bistriaria, 7046, Red-fringed Emerald Moth

Lobocleta ossularia, 7094, Drab Brown Wave Moth

Lobocleta ossularia 7094, Drab Brown Wave Moth LASIOCAMPIDAE—LAPPET, TOLYPE, AND TENT CATERPILLAR MOTH FAMILY (7670–7702)

Idaea obfusaria, 7123, Rippled Wave Moth

Cyclophora nanaria, 7140, Dwarf Tawny Wave Moth

Hammaptera parinotata, 7314

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SATURNIIDAE—GIANT SILKMOTH FAMILY (7704–7770)

Phyllodesma americana, 7687, Lappet Moth

Malacosoma disstria, 7698, Forest Tent Caterpillar Moth

Syssphinx hubbardi, 7711, Hubbard’s Small Silkmoth

SPHINGIDAE—SPHINX, CLEARWING, AND HAWK MOTH FAMILY (7771–7894)

Manduca quinquemaculata, 7776, Five-spotted Hawk Moth

Laothoe juglandis, 7827, Walnut Sphinx

Erinnyis obscura, 7837, Obscure Sphinx Moth

Litodonta hydromeli, 7968

Heterocampa astarte, 7977, Astarte Prominent Moth

NOTODONTIDAE—PROMINENT AND DATANA MOTH FAMILY (7895–8032)

Hyles lineata, 7894, White-lined Sphinx

ARCTIIDAE—LICHEN AND TIGER MOTH FAMILY (8033–8288)

Heterocampa astarte, 7977, Astarte Prominent Moth

Heterocampa obliqua, 7983, Oblique Heterocampa Moth

Lochmaeus bilineata, 7999, Double-lined Prominent Moth NOCTUIDAE—OWLET MOTH FAMILY (8322–11233)

Cisthene tenuifascia, 8066, Three-banded Lichen Moth

Lycomorpha pholus, 8087, Black-and-Yellow Lichen Moth

Holomelina sp., 8114–8124, Homomelina Moth genus

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Sigela basipunctaria, 8434, Spotted Sigela Moth

Hypena scabra, 8465, Green Cloverworm Moth

Tathorhynchus exsiccatus, 8466

Panopoda carneicosta, 8588, Brown Panopoda Moth

Phoberia atomaris, 8591, Common Oak Moth

Melipotis indomita, 8600, Indomitable Melipotis Moth

Melipotis jucunda, 8607, Merry Melipotis Moth

Melipotis jucunda 8607, Merry Melipotis Moth

Bulia deducta, 8614, Bulia Moth

Drasteria howlandi, 8639,

Heteranassa mima, 8659, Heteranassa Moth

Heteranassa mima 8659, Heteranassa Moth

Zale lunata, 8689, Lunate Zale Moth

Zale edusina, 8693

Zale edusina, 8693

Eubolina impartialis, 8720

Caenurgina erechtea, 8739, Forage Looper

Caenurgina erechtea 8739, Forage Looper

Caenurgina erechtea 8739, Forage Looper

Aon noctuiformis, 8954

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Meganola sp., 8983–8988

Catocala maestosa, 8793, Sad Underwing

Cydosia aurivitta, 8999

Tarachidia binocular, 9089

Acontia aprica, 9136, Exposed Bird-dropping Moth

Acontia tetragona, 9143, Four-spotted Birddropping Moth

Alypia octomaculata, 9314, Eight-spotted Forester

Phosphila miselioides, 9619, Spotted Phosphila Moth

Galgula partita, 9688, Wedgling

Emarginea percara, 9718, Beloved Emarginea Moth

Stiriodes obtusa, 9725, Obtuse Yellow Moth

Catabena lineolata, 10033, Fine-lined Sallow Moth

Cucullia laetifica, 10191

Faronta diffusa, 10431, Wheat Head Armyworm Moth

Faronta rubripennis, 10434, Pink Streak

Leucania sp., 10439–10463 Wainscot Moth

Feltia subterranea, 10664, Subterranean Dart Moth

Hemieuxoa rudens, 10914

Schinia hulstia, 11193

Schinia citrinellus, 11204

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Dragonflies and Damselflies Dragonflies and their damselfly cousins come in a huge variety of dazzling colors. There are at least 89 species of dragonflies and 42 species of damselflies that may be in range in Llano, Gillespie, and Mason counties. Dragonflies are larger, with four wings perpendicular to the body, which they leave unfolded when at rest. Damselflies look more delicate, with wings that are typically folded over the body when at rest. A few species of damselflies keep their wings unfolded when at rest. Dragonfly and damselfly activity kicks off in early to mid-spring, with their numbers peaking in the late spring to early summer. Most prefer to have water nearby, where they can lay their eggs to complete their mating cycle. In some species, the male dragonfly drags the female of the species around by the neck as the female dips her tail in the water. The nymphs are hatched and grow in the water until they metamorphose into flying adults. Water also tends to concentrate their food supply of small flying insects, such as gnats or mosquitoes. Red saddlebags may be found in groups of a few dozen, flying in patterns farther away from water sources. Individuals of the Gomphidae and Aeshnidae families also range well away from water. A great place to watch dragonfly activity is at Frog Pond, where you can find many species of dragonflies and damselflies hunting bugs and each other. The small damselflies hide in the tall grass

to avoid larger damselflies and dragonflies. Small damselflies are hunted by larger ones, such as the Lestes genus. In turn, the damselflies are hunted by small (and large) dragonflies. At the top of the dragonfly food chain are the Tramea and Anax geneta, which constantly cruise over the water, engaging in dogfights with smaller species. Sandy Creek, Walnut Springs Creek, and Moss Lake also provide excellent Odonata habitat. Some species, such as the variegated meadowhawk, or roseate skimmer, if scared away from a stick perch, will return to it if you remain still. You can then get a good look at them. Other species, such as black saddlebags, prefer to keep on the wing, hunting relentlessly. In the field, dragonflies are easier to identify than damselflies because they are larger. Damselflies require a closer look, through either a photographic lens and camera or short-range binoculars. Even close up, some species can be quite difficult to distinguish from other species. Try to match patterns on the tail and thorax, body color, markings on the wings, and shape of the end of the tail. Damselflies may be even more challenging to identify, as a fair number of species come in a sky-blue model with subtle striping differences on the thorax. After molting, the fresh dragonfly or damselfly is said to be teneral, with a soft body that hardens, bringing out the beautiful colors.

odonata—dragonfly and damselfly order Anisoptera—Dragonfly Suborder AESHNIDAE—DARNER DRAGONFLY FAMILY

CORDULIIDAE—EMERALD DRAGONFLY FAMILY

Anax junius, Common Green Darner

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Epitheca princeps, Prince Baskettail (teneral)

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GOMPHIDAE—CLUBTAIL DRAGONFLY FAMILY

Erpetogomphus designatus, Eastern Ringtail

Gomphus militaris, Sulphur-tipped Clubtail

Phyllogomphoides stigmatus, Four-striped Leaftail

LIBELLULIDAE—SKIMMER DRAGONFLY FAMILY

Progomphus borealis, Gray Sanddragon

Progomphus obscurus, Common Sanddragon

Brechmorhoga mendax, Pale-faced Clubskimmer

Celithemis eponina, Halloween Pennant

Celithemis fasciata, Banded Pennant

Dythemis fugax, Checkered Setwing

Dythemis velox, Swift Setwing

Erythemis simplicicollis (male), Eastern Pondhawk

Erythemis simplicicollis (female), Eastern Pondhawk

Libellula comanche, Comanche Skimmer

Libellula croceipennis, Neon Skimmer

Libellula luctuosa, Widow Skimmer

Libellula luctuosa, Widow Skimmer

Libellula pulchella (male), Twelve-spotted Skimmer

Brachymesia furcata, Red-tailed Pennant

drag on f l ies falnora d daamnd selfauna f l ies

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Libellula pulchella (female), Twelve-spotted Skimmer

Orthemis ferruginea (male), Roseate Skimmer

Orthemis ferruginea (female), Roseate Skimmer

Pachydiplax longipennis, Blue Dasher

Plathemis lydia (male), Common Whitetail

Plathemis lydia (female), Common Whitetail

Sympetrum corruptum (male), Variegated Meadowhawk

Sympetrum corruptum, Variegated Meadowhawk

Sympetrum corruptum, Variegated Meadowhawk

Tramea lacerate, Black Saddlebags and unknown

Tramea lacerate, Black Saddlebags

Tramea onusta, Red Saddlebags

Tramea onusta, Red Saddlebags

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zygoptera—damselfly suborder

CALOPTERYGIDAE—BROAD-WINGED DAMSELFLY FAMILY

Hetaerina americana, American Rubyspot

Hetaerina americana, American Rubyspot

Hetaerina americana, American Rubyspot

Argia fumipennis violacea, Violet Dancer

Argia immunda (male), Kiowa Dancer

Argia immunda (female), Kiowa Dancer

Argia moesta, Powdered Dancer

Argia nahuana, Aztec Dancer

Argia plana (likely), Springwater Dancer

Argia sedula, Blue-ringed Dancer

Argia translata, Dusky Dancer

Enallagma basidens (male), Double-striped Bluet

Enallagma basidens (female), Double-striped Bluet

Enallagma civile (male), Familiar Bluet

COENAGRIONIDAE—NARROW-WINGED DAMSELFLY FAMILY

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Enallagma civile (female) Familiar Bluet

Ischnura hastata, Citrine Forktail

Telebasis salva (male), Desert Firetail

Telebasis salva (female) Desert Firetail

Archilestes grandis (male), Great Spreadwing

Archilestes grandis (female), Great Spreadwing

Archilestes grandis Great Spreadwing

LESTIDAE—SPREADWING DAMSELFLY FAMILY

Lestes alacer, Plateau Spreadwing

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Grasshoppers, Katydids, and Crickets Although grasshoppers can be found in any month, the better times to look are from March until the first hard freeze occurs. They peak in the late summer into fall, when the majority of grasses are at their peak. Identification of grasshoppers can be quite challenging, especially during the nymph phase. Experts often require specimens in hand to perform a proper ID, looking at the details on the outside and inside of the leg, exterior and interior wing pattern, pronotum, and genitalia.

One interesting species is the Aztec range grasshopper, which has coloration allowing it to blend in with granite. Katydids and crickets are mostly nocturnal, and more difficult to locate. You can certainly hear them, as they make various buzzing and clicking noises. Identification to the species level often requires hand inspection or listening to the call.

orthoptera—grasshopper, katydid, and cricket order Caelifera—Short-horned Grasshopper and Cricket Suborder ACRIDIDAE—SHORT-HORNED GRASSHOPPER FAMILY CYRTACANTHACRIDINAE—MIGRATORY BIRD LOCUST SUBFAMILY

Melanoplus differentialis, Differential Grasshopper

Melanoplus foedus, Striped Sand Grasshopper

Melanoplus glaucipes, Glaucous-legged Spur-throated Grasshopper

Melanoplus ponderosus, Ponderous Spur-throated Grasshopper

Melanoplus ponderosus, Ponderous Spur-throated Grasshopper

Melanoplus ponderosus, Ponderous Spur-throated Grasshopper

Schistocerca americana, American Bird Grasshopper

Schistocerca lineata, Spotted Bird Grasshopper

Schistocerca lineata, Spotted Bird Grasshopper

Schistocerca lineata, Spotted Bird Grasshopper

Schistocerca nitens, Gray Bird Grasshopper

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GOMPHOCERINAE—SLANT-FACED GRASSHOPPER SUBFAMILY

Amblytropidia mysteca, Brown Winter Grasshopper

Boopedon gracile, Graceful Range Grasshopper

Mermiria bivittata, Two-striped Mermiria Grasshopper

Mermiria bivittata, Two-striped Mermiria Grasshopper

Mermiria picta, Lively Mermiria Grasshopper

Opeia obscura, Obscure Grasshopper

Orphulella speciosa (likely), Pasture Grasshopper

Psoloessa texana, Texas Spotted Range Grasshopper

Syrbula admirabilis, Handsome Grasshopper

Syrbula admirabilis, Handsome Grasshopper

Syrbula admirabilis, Handsome Grasshopper

Arphia conspersa, Speckled Rangeland Grasshopper

Arphia conspersa, Speckled Rangeland Grasshopper

Arphia simplex, Plains Yellow-winged Grasshopper

Arphia simplex, Plains Yellow-winged Grasshopper

OEDIPODINAE—BAND-WINGED GRASSHOPPER SUBFAMILY

Syrbula montezuma, Montezuma Grasshopper

Arphia conspersa, Speckled Rangeland Grasshopper

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Arphia simplex, Plains Yellow-winged Grasshopper

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Arphia simplex, Plains Yellow-winged Grasshopper

Chortophaga viridifasciata, Northern Greenstriped Grasshopper

Chortophaga viridifasciata, Northern Greenstriped Grasshopper

Hippiscus ocelote, Wrinkled Grasshopper

Lactista azteca, Aztec Range Grasshopper

Lactista azteca, Aztec Range Grasshopper

Lactista azteca, Aztec Range Grasshopper

Spharagemon cristatum, Ridgeback Sand Grasshopper

Spharagemon equale, Say’s Grasshopper

Trimerotropis pallidipennis, Pallid-winged Grasshopper

Trimerotropis pallidipennis, Broad-banded Grasshopper

Trimerotropis pallidipennis, Broad-banded Grasshopper

Arethaea grallator (likely), Stilt-walker Katydid

Microcentrum rhombifolium, Greater Anglewing Katydid

Orchelimum bullatum (likely), Texas Meadow Katydid

Pediodectes haldemani, Haldeman’s Shieldbacked Katydid

Pediodectes stevensoni, Stevenson’s Shieldbacked Katydid

Scudderia furcata, Fork-tailed Bush Katydid

Ensifera—Long-Horned Cricket and Katydid Suborder TETTIGONIIDAE—KATYDID FAMILY

Pediodectes haldemani, Haldeman’s Shieldbacked Katydid

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Scudderia furcata, Fork-tailed Bush Katydid

Scudderia texensis (likely), Texas Bush Katydid

Scudderia sp. (nymph), Bush Katydid genus

GRYLLACRIDIDAE—RASPY CRICKET FAMILY

Scudderia sp. (nymph), Bush Katydid genus

GRYLLIDAE—TRUE CRICKET FAMILY

Gryllacrididae, Raspy Cricket

Scudderia sp. (nymph), Bush Katydid genus

Gryllus sp., Field Cricket genus

Gryllus sp., Field Cricket genus

Oecanthus sp., Tree Cricket genus

Oecanthus sp., Tree Cricket genus

Gryllus sp., Field Cricket genus

Gryllus sp., Field Cricket genus

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Bees, Wasps, Hornets, and Flies Bees include the common honey bee and many others. A number of flies mimic bees; careful inspection is necessary to tell them apart. Africanized killer bees are in range but do not necessarily pose a threat, as long as you do not mess with bee hives, which are often found in trees. There are many types of wasps in a variety of colors, such as red, purple, and black. Although wasps may check you out while hiking, they rarely sting unless their nest is disturbed. Nests are frequently found around buildings. Many species of wasps fly into grassy areas, looking for prey in which to lay their eggs. Large

black tarantula hawk wasps sting spiders and lay their eggs in them, making the future life of the spider rather difficult. Hornets are common around the park picnic area, where there are sweet liquids to be had in the trash bins. They may be a problem for picnickers who are not closely defending their lunches. Note that although ants are in the same order as bees and wasps, they are covered under “Other Insects.” There is much reorganization of the bees and wasps within superfamilies, families, and other taxonomic classifications.

diptera—fly order aSilidae—robber Fly Family

Diogmites sp., Hanging Thief genus

Efferia sp., Robber Fly genus

Efferia sp., Robber Fly genus

bombyliidae—bee Fly Family anthraCinae SubFamily exoproSopini tribe

Efferia sp., Robber Fly genus

Exoprosopa iota, Bee Fly

Promachus bastardii, Robber Fly

Villini tribe

Exoprosopa sp., Bee Fly genus

Hemipenthes sinuosa, Sinuous Bee Fly

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Neodsplocampta sp. Bee Fly

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eCliminae SubFamily

phthiriinae SubFamily

Lepidophora sp., Bee Fly genus

Poecilognathus sp., Bee Fly genus

Calliphoridae—blowFly Family

Cynomya cadaverina, Blowfly

Conopidae—thiCk-headed Fly Family

Cochliomyia macellaria, Secondary Screwworm

Lucilia sp., Blowfly genus

doliChopodidae—lonG-leGGed Fly Family

Physoconops sp., Thick-headed Fly

SarCophaGidae—FleSh Fly Family

Condylostylus sp. Long-legged Fly genus,

Stratiomyidae—Soldier Fly Family

Sarcophaga sp., Flesh Fly genus

Odontomyia sp., Soldier Fly genus

Syrphidae—Syrphid Fly Family

VoluCellini tribe

eriStalinae SubFamily eriStalini tribe

Eristalis sp., Hover Fly genus

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Eristalis sp., Hover Fly genus

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Syrphinae SubFamily Syrphini tribe

Copestylum mexicana, Mexican Cactus Fly

Allograpta sp., Hover Fly genus

Ocyptamus fascipennis, Hover Fly

tabanidae—horSe Fly Family

Ocyptamus fuscipennis, Hover Fly

Toxomerus sp., Hover Fly genus

Toxomerus marginatus, Hover Fly

taChinidae—taChinid Fly Family

Hybomitra sp. (or Tabanus), Horse Fly genus

Tachinidae, Tachinid Fly

Tachinidae, Tachinid Fly

Gymnoclytia sp., Tachinid Fly genus

Trichopoda sp., Tachinid Fly genus

phaSiinae SubFamily

Cylindromyia sp., Tachinid Fly genus

taChininae SubFamily

Trichopoda sp., Tachinid Fly genus

Tipula sp., Crane Fly genus

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hymenoptera—ant, bee, and wasp order

apoidea—bee and SpeCid waSp SuperFamily

bombini—bumble bee tribe

apidea—honey, bumble, Carpenter, and other beeS Family apinea—honey, bumble, StinGleSS, and other beeS SubFamily apini—honey bee tribe

Apis mellifera, Honey Bee

xyloCopinae—Carpenter bee SubFamily

Bombus pensylvanicus (likely), American Bumble Bee Crabronidae—waSp Family

Xylocopa virginica (likely), Eastern Carpenter Bee

Bicyrtes sp., Sand Wasp genus

haliCtidae—Sweat bee Family auGoChlorini tribe

Sphecius speciosus (likely), Cicada Killer

meGaChilidae—leaFCutter bee Family

SpheCidae—thread-waiSted waSp Family

Megachile sp., Leafcutter Bee genus

236

Augochloropsis sp., Sweat Bee genus

Steniolia sp., Sand Wasp genus

Ammophila sp., Mud Dauber Wasp genus

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Chalybion sp. (likely), Mud Dauber Wasp genus

Chalybion sp. (likely), Mud Dauber Wasp genus

Sceliphron caementarium, Black-and-Yellow Mud Dauber

Sceliphron caementarium (nest), Black-andYellow Mud Dauber

Disholcaspis cinerosa (likely), Mealy Oak Gall Wasp

Cynipidae (gall on catclaw mimosa), Gall Wasp

Cynipoidea—Gall and paraSitoid waSp SuperFamily Cynipidae—Gall waSp Family

Sphex ichneumoneus, Great Golden Digger Wasp iChneumonoidea—iChneumon waSp SuperFamily

VeSpoidea—waSp SuperFamily pompilidae—Spider waSp Family

iChneumonidae—iChneumon waSp Family

Ichneumonidae, Ichneumon Wasp

Ichneumonidae, Ichneumon Wasp

VeSpidae—yellowjaCket, hornet, potter, and paper waSp Family eumeninae—potter waSp SubFamily

Pepsis sp., Tarantula Hawk genus

Tachypompilus sp., Spider Wasp genus

Eumenes sp., Potter Wasp genus

poliStinae—paper waSp SubFamily

Eumeninae, Potter Wasp subfamily

Polistes annularis, Paper Wasp

Polistes carolina, Red Wasp

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Polistes carolina, Red Wasp

Polistes exclamans, Paper Wasp

Polistes sp., Paper Wasp genus

Vespula maculifrons, Eastern Yellowjacket

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Polistes fuscatus, Northern Paper Wasp

Polistes metricus, Yellow-kneed Wasp

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Other Insects The total number of insect species at Enchanted Rock SNA is not known. There have been no extensive surveys of insects in the area; however, representative species of your favorite bug type are probably present. Walking sticks and praying mantises, present throughout the park, may be spotted around the campground restrooms and the visitor center office on warm nights in late spring. More challenging is to find them on shrubs, trees, or other plants. Mosquito and gnat numbers increase with wet conditions in the spring. In most years, the mosquitoes and gnats have a short, intense period of activity following warm temperatures and ample

rainfall in late spring. They may be present in any month except the winter months, but in general they are not a serious source of annoyance. June bugs are those noisy, poor-flying, reddish brown beetles that taunt campers in the late spring to early summer. Attracted by camp lights, they come crashing into the area. They won’t hurt anything, but a collision with one can be quite shocking. Other bugs present at the park are too numerous to describe. The species included here are those encountered and successfully photographed. They are sorted by order, then family, and then other taxonomic units where appropriate. Many are identified only to the family level.

coleoptera—beetle order

Adephaga—Ground and Water Beetle Suborder Carabidae—Ground beetle Family

dytiSCidae—PredaCeouS divinG beetle Family

CiCindelinae—tiGer beetle SubFamily

Cicindela sp., Tiger Beetle genus

Dytiscidae, Predaceous Diving Beetle

Polyphaga—Water, Rove, Scarab, Long-horned, Leaf, and Snout Beetle Suborder buPreStidae—metalliC Wood-borinG beetle Family

CerambyCidae—lonG-horned beetle Family

Acmaeodera ornata, Metallic Wood-boring Beetle

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Cerambycidae, Long-horned Beetle

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CerambyCinae—lonG-horned beetle SubFamily

lamiinae—Flat-FaCed lonG-horned beetle SubFamily

Batyle ignicollis, Fire-necked Batyle Beetle

Prioninae—lonG-horned beetle SubFamily

Lamiinae, Flat-faced Long-horned Beetle subfamily ChrySomelidae—leaF beetle Family

Mallodon sp.

Diabrotica sp., Leaf Beetle genus

CoCCinellidae—ladybird beetle Family

Diabrotica undecimpunctata, Leaf Beetle

Harmonia axyridis, Multicolored Asian Lady Beetle

CurCulionidae—Snout and bark beetle Family

elateridae—CliCk beetle Family

Curculio sp., Nut Weevil genus

Elateridae, Click Beetle

GeotruPidae—earth-borinG dunG beetle Family

Elateridae, Wireworm

240

Harmonia axyridis, Multicolored Asian Lady Beetle

lyCidae—net-WinGed beetle Family

Geotrupes sp., Earth-boring Dung Beetle genus

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meloidae—bliSter beetle Family

Lycus sp., Net-winged Beetle genus

Epicauta sp., Blister Beetle genus

SCarabaeidae—SCarab beetle Family

Pyrota insulata, Yellow-crescent Blister Beetle

rutelinae—ShininG leaF ChaFer SubFamily

melolonthinae—may beetle and June buG SubFamily

Phyllophaga sp., June Bug genus

Phyllophaga sp., June Bug genus

tenebrionidae—darklinG beetle Family

oPatrinae—SubFamily

alleCulinae—Comb-ClaWed beetle SubFamily

Pelidnota punctata, Grapevine Beetle

Eleodes sp., Darkling Beetle genus

Alleculinae, Comb-clawed Beetle

Eleodes sp., Darkling Beetle genus

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dictyoptera—mantid and cockroach order

mantidae—PrayinG mantiS Family

eCtobiidae—roaCh Family

Ectobiidae, Cockroach

Mantidae (egg sac), Praying Mantis

Mantidae (egg sac), Praying Mantis

Mantidae, Praying Mantis

Brunneria borealis, Brunner’s Mantis

Oligonicella scudderi, Praying Mantis

ephemeroptera—mayfly order

ePhemeridae—Common burroWer mayFly Family

Hexagenia sp., Mayfly genus

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Hemiptera—true bug order

berytidae—Stilt buG Family

aPhididae—aPhid Family

Aphididae, Aphid

CerCoPidae—SPittlebuG Family

Jalysus sp., Stilt Bug genus

CiCadidae—CiCada Family

Cercopidae, Spittlebug

Tibicen dorsata, Cicada

Coreidae—leaF-Footed buG Family

Tibicen superba, Superb Cicada

Cicadidae (exoskeleton), Cicada

Acanthocephala terminalis, Leaf-footed Bug

Chelinidea vittiger (nymph), Cactus Coreid

Acanthocephala femorata, Leaf-footed Bug

Chelinidea vittiger (nymph), Cactus Coreid

Chelinidea vittiger, Cactus Coreid

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Gerridae—Water Strider Family

Leptoglossus phyllopus, Leaf-footed Bug

Mozena sp., Leaf-footed Bug genus

Narnia femorata, Cactus Bug

larGidae—bordered Plant buG Family

Gerris sp., Water Strider genus

Largus sp., Bordered Plant Bug genus

lyGaeidae—Seed buG Family

Largus sp., Bordered Plant Bug genus

miridae—Plant buG Family

Oncopeltus fasciatus, Large Milkweed Bug

Calocoris barberi, Plant Bug

Pentatomidae—Stink buG Family

Acrosternum hilare, Green Stink Bug

Brochymena sp., Stink Bug genus

Euschistus sp., Stink Bug genus

reduviidae—aSSaSSin buG Family

Euschistus sp., Stink Bug genus

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Thyanta sp., Stink Bug genus

Apiomerus sp., Assassin Bug genus

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Apiomerus sp., Assassin Bug genus

Arilus cristatus, Wheel Bug

Rasahus sp., Assassin Bug genus

Stenopoda cinerea, Assassin Bug

Triatoma gerstaeckeri, Bloodsucking Conenose

hymenoptera—ant, bee, and wasp order

FormiCidae—ant Family

Camponotus sp., Carpenter Ant genus

Pogonomyrmex sp., Harvester Ant genus

Solenopsis invicta, Fire Ant

mutillidae—velvet ant Family

Dasymutilla sp., Velvet Ant genus

ot her sects f l ora a ndinfauna

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isopoda—isopod order

ArmAdillidiidAe—Pill Bug FAmily

Armadillidium vulgare, Pillbug

neuroptera—antlion and lacewing order

AscAlAPhidAe—OwlFly FAmily

chrysOPidAe—green lAcewing FAmily

Ululodes hyalina, Owlfly

Chrysopidae, Green Lacewing

myrmeleOntidAe—AntliOn FAmily

Chrysopidae, Green Lacewing

Brachynemurus sp., Antlion genus

Myrmeleon sp., Antlion genus

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Phasmatodea—Walkingstick Superorder heterOnemiidAe—cOmmOn wAlking stick FAmily

Megaphasma dentricus, Giant Walking Stick

Megaphasma dentricus, Giant Walking Stick

Megaphasma dentricus, Giant Walking Stick

Megaphasma dentricus, Giant Walking Stick

spirobolida—millipede order

sPirOBOlidAe

Narceus sp., Millipede genus

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Arachnids Arachnids include spiders, scorpions, and other eight-legged creatures. Many spiders are for the most part nocturnal, so you are less likely to see them in the daytime. Look for the Z-shaped structure in the middle of the yellow and black Argiope garden spider. Wolf spiders can be found in the grass at night; the mothers are often seen carrying their babies on their backs. Many wasps go hunting for spiders in the grass during the daytime. It is interesting to watch the spiders maneuver in the grass to avoid the search pattern of the wasp. Giant lichen orb weaver spiders build huge webs between

trees, but they and their webs are not commonly seen. Harvestmen are not true spiders; they are frequently referred to as daddy longlegs (a name also given to a species of true spider). Scorpions come out at night, but during the day make sure you are not moving rocks or logs without checking on the ground and on the rock or log. Poisonous spiders that are in range at the park include the brown recluse, black widow, and tarantula. You are unlikely to be bitten by any of them unless you are looking for trouble.

Araneae—Spider Order AgelenidAe—Funnel weB sPider FAmily

Agelenidae, Funnel Web Spider

Agelenidae, Funnel Web Spider

Agelenidae, Funnel Web Spider

Araneus bicentenarius, Giant Lichen Orb Weaver

Araneus detrimentosus, Orb Weaver

Argiope aurantia, Black-and-Yellow Argiope

Argiope trifasciata, Banded Argiope

Argiope trifasciata, Banded Argiope

Argiope trifasciata, Banded Argiope

ArAneidAe—OrB weAver sPider FAmily

Argiope aurantia, Black-and-Yellow Argiope

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Gasteracantha cancriformis, Crablike Spiny Orb Weaver

Mangora gibberosa, Orb Weaver

Neoscona crucifera, Orb Weaver

Neoscona crucifera, Orb Weaver

FilistAtidAe—crevice weAver sPider FAmily

Araneidae, Orb Weaver

Kukulcania hibernalis, Southern House Spider

Araneidae, Orb Weaver

lycOsidAe—wOlF sPider FAmily

Rabidosa sp., Wolf Spider

Rabidosa sp., Wolf Spider

Lycosidae, Wolf Spider

OxyOPidAe—lynx sPider FAmily

Lycosidae, Wolf Spider

Peucetia viridans, Green Lynx Spider

Lycosidae, Wolf Spider

PisAuridAe—nursery weB sPider FAmily

Peucetia viridans, Green Lynx Spider

sAlticidAe—JumPing sPider FAmily

Dolomedes sp., Fishing Spider genus

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scytOdidAe—sPitting sPider FAmily

Phidippus audax, Daring Jumping Spider

Phidippus audax, Daring Jumping Spider

sicAriidAe—viOlin sPider FAmily

Scytodidae, Spitting Spider

tetrAgnAthidAe—lOng-JAwed OrB weAver sPider FAmily

Loxosceles reclusa, Brown Recluse

Tetragnathidae, Long-jawed Orb Weaver

thOmisidAe—crAB sPider FAmily

Thomisidae, Crab Spider

Thomisidae, Crab Spider

Thomisidae, Crab Spider

opiliones—harvestman order

Phalangiidae, Harvestman

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scorpiones—scorpion order

BUTHIDAE

Centruroides vittatus, Striped Bark Scorpion

f l ora a rachn nd fauna id s

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Historical Timeline

s Century

Century

Event

1500–1600

1519 First Spanish exploration of Texas coastline

1756 Miranda y Flores expedition possibly records Enchanted Rock as Cerro de Santiago

1527–1536 Shipwrecked Cabeza de Vaca travels across South and Central Texas to reach Spanish territory

1757 San Saba Mission and Presidio built 1758 San Saba Mission destroyed by Norteña

1500s–1600s Spanish claim North America from Florida to California 1539–1543 De Soto and Moscoso explore much of the future southeastern United States, including Central Texas 1600–1700

1769 San Saba Presidio abandoned 1800–1900

1600s–1700s Numerous Spanish entradas into Texas 1685 French establish Fort St. Louis 1690 insurrections in New Mexico pueblos drive Spanish out 1682 Spanish begin establishing missions in Texas

1700–1800

1803 Louisiana Purchase 1810–1821 Mexican War of Independence, Mexico breaks away from Spain 1821 Moses Austin wins land grant from Mexico, son Stephen F. Austin carries on after Moses’ death 1826–1827 Fredonia Rebellion 1829 Capt. Henry S. Brown explores Enchanted Rock on behalf of Stephen F. Austin

1718 Presidio San Antonio de Béjar and Mission San Antonio de Valero established

1829 Slavery outlawed in Mexico

Early 1700s Tonkawa displaced by Lipan Apache

1833 Santa Anna wins Mexican presidency

Middle 1700s Lipan Apache displaced by Comanche

1835–1836 Republic of Texas declares independence, wins against Mexicans

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Event

1830 Mexican law prohibits immigration from United States

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Century

Event 1838 Land including Enchanted Rock granted to Anavato Martinez 1841 Texas Ranger Capt. Jack Hays has gun battle atop Enchanted Rock with Comanche 1842 Mainzer Adelsverein established to purchase land in Texas 1843 D’Orvanne land grant expires 1844 Solms-Braunfels comes to Texas 1845 Fredericksburg established 1847 Extension of Fisher-Miller land grant expires 1847 Land including Enchanted Rock patented by Samuel Maverick 1850 Population of 1,213 in Gillespie County, 916 of European origin, mostly German 1856 Llano, Mason counties established

Century

Event 1861–1865 Civil War 1871–1878 Lungkwitz paints Enchanted Rock and Central Texas 1875 Last Native American hostilities in Central Texas 1890 Last Native American groups in Texas moved to Oklahoma

1900–present 1927 Private Enchanted Rock Park established 1979 Natural surveys around Enchanted Rock 1979 Nature Conservancy buys Enchanted Rock land from Moss Family 1984 Enchanted Rock State Natural Area opened 1984 Enchanted Rock placed on National Historic Register 1999 Visitation limited when park fills

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Endemic and Unusual Plants

s The following is a selection of endemic and unusual plants found within the Llano Uplift. (The data sources are the Texas A&M University Web site at www.csdl.tamu.edu/FLORA/ cgi/endemics_map_page2?all=yes and Diggs et al., Shinners and Mahler’s Illustrated Flora of North Central Texas, with nomenclature updates from http://plants.usda.gov.)

Blechnaceae Blechnum occidentale (hammock fern)—found in a sheltered area at Enchanted Rock SNA, well outside its home range in Mexican mountains. Also found in isolated locations in Louisiana, Georgia, and Florida

Acanthaceae

Boraginaceae

Ruellia drummondiana (Drummond’s ruellia)—endemic to Texas, found within and south of Llano Uplift

Cryptantha texana (Texas cryptantha)—endemic to Central and South Texas

Agavaceae

Brassicaceae

Aristolochia coryi (Cory’s Dutchman’s pipevine)—well outside its range in West Texas counties

Arabis petiolaris (Brazos rockcress)—endemic to Edwards Plateau, found in Llano Uplift and along Balcones Escarpment Lesquerella densiflora (dense-flower bladderpod)—endemic to Texas, found in Llano Uplift and in scattered counties to the north and east Lesquerella grandiflora (big-flower bladderpod)—endemic to Texas, found in Llano Uplift extending into South Texas Lesquerella recurvata (slender bladderpod)— endemic to Texas, found in eastern Edwards Plateau and to the northeast

Asteraceae

Campanulaceae

Verbesina lindheimeri (Lindheimer’s crownbeard)—endemic to Edwards Plateau, found in Llano Uplift and southeast Edwards Plateau

Campanula reverchonii (basin bellflower)— endemic to Llano Uplift and a couple of counties along Balcones Escarpment

Nolina lindheimeriana (devil’s shoestring)— endemic to southeast Edwards Plateau Yucca constricta (Buckley’s yucca)—endemic to Edwards Plateau and South Texas Yucca rupicola (twisted-leaf yucca)—endemic to eastern Edwards Plateau

Aristolochiaceae

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Cistaceae Lechea san-sabeana (San Saba pinweed)—endemic to Texas, found in Llano Uplift and in scattered counties throughout East Texas

Commelinaceae Tinantia anomala (false dayflower)—endemic to Edwards Plateau, especially along Balcones Escarpment Tradescantia edwardsiana (plateau spiderwort)—endemic to scattered counties extending from North to South Central Texas Tradescantia gigantea (giant spiderwort)— found in Llano Uplift and east past Balcones Escarpment. Also found in scattered counties in Louisiana Tradescantia pedicellata (Edwards Plateau spiderwort)—endemic to Llano Uplift, found only in Llano, Mason, McCulloch, Blanco, and Burnet counties Tradescantia subacaulis (stemless spiderwort)—endemic to Texas, found in Llano Uplift and East Texas

Convolvulaceae Dichondra recurvata (oakwoods ponysfoot)— endemic to Texas, found in eastern Edwards Plateau

Euphorbiaceae Chamaesyce angusta (black-foot euphorbia)— endemic to Edwards Plateau

Fabaceae Astragalus crassicarpus var. berlandieri (ground-plum)—endemic to eastern Edwards Plateau, extending across Balcones Escarpment Astragalus nuttallianus var. pleianthus (Edwards Plateau milkvetch)—endemic to Edwards Plateau and counties to the east and south Dalea tenuis (pink-globe prairie clover)— endemic to Central Texas Galactia heterophylla (Gray’s milkpea)—endemic to Llano County and in South Texas

Tephrosia lindheimeri (Lindheimer’s tephrosia)—endemic to Llano Uplift and South Texas

Fumariaceae Corydalis curvisiliqua ssp. curvisiliqua (curvepod corydalis)—endemic to western Texas

Isoetaceae Isoetes lithophila (rock quillwort)—endemic to Llano Uplift, found only in Llano, Gillespie, Mason, and Burnet counties

Juncaceae Juncus validus var. fascinatus (roundhead rush)—endemic to Texas, found in Llano County and eastern Edwards Plateau counties, also in scattered counties to the north and southeast

Liliaceae Allium elmendorfii (Elmendorf ’s onion)— endemic to Texas, found in Llano County and in other disjoint counties to the southeast

Marsileaceae Pilularia americana (American pillwort)— isolated populations in weathering pits atop granite domes, far from its home range in states to the north and west

Ophioglossaceae Ophioglossum crotalophoroides (Adder’s tongue)—the westernmost occurrence of this plant

Poaceae Tripogon spicatus (American tripogon)— endemic to Llano Uplift

Polemoniaceae Phlox pilosa ssp. latisepala (rough phlox)— endemic to Edwards Plateau

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Phlox roemeriana (Texas phlox)—endemic to Edwards Plateau

Polygonaceae Eriogonum tenellum var. ramosissimum (tall buckwheat)—endemic to Llano Uplift, found only in Llano, Gillespie, Mason, and Burnet counties

Eriocaulon koernickianum (smallhead pipewort)—an isolated population in Gillespie County. The plant exists in other Northeast Texas counties and in Georgia, Arkansas, and Oklahoma

Scrophulariaceae

Cheilanthes kaulfussii (Kaulfuss’ lipfern)—a population in Llano Uplift, far from its West Texas and Mexico home range

Penstemon guadalupensis (Guadalupe penstemon)—endemic to Edwards Plateau and scattered counties to the northwest Penstemon triflorus ssp. triflorus (Heller’s beardtongue)—endemic to counties on periphery of Llano Uplift within Edwards Plateau

Ranunculaceae

Styracaceae

Clematis texensis (scarlet leatherflower)— endemic to Llano Uplift and eastern Edwards Plateau

Styrax platanifolius (sycamore-leaf snowbell)— endemic to southern Edwards Plateau

Pteridaceae

Rosaceae Prunus serotina var. eximia (escarpment blackcherry)—endemic to Llano Uplift and south to boundary of Balcones Escarpment Prunus texana (peach bush)—endemic to Llano Uplift and to the southeast

Valerianaceae Valerianella texana (Edwards Plateau cornsalad)—endemic to Llano Uplift

Vitaceae Parthenocissus heptaphylla (seven-leaf creeper)—endemic to Central Texas

refleren ces endem ic a nd unusua pl a nts

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Enchanted Rock SNA Landmarks and Trails

s

At Enchanted Rock SNA, some granite domes, small creeks, and even trails do not have commonly accepted names. Given the popularity of the park, it is not clear why more of these features are not named. This book introduces names where necessary to help describe and identify locations. The following feature names have been introduced on the accompanying map: North Dome (west and east), West Little Rock Dome, Little Rock Dome Spur, Boundary Rocks, False Dome, Viewpoint Dome, Forgotten Dome, Lost Dome,

Echo Granite Outcrop, Campside Creek, Backside Creek, Moss Creek, Waterfall Creek, and North Walnut Springs Creek. Other introduced trail names are Backside, Frontside, Walnut Springs Loop, Buzzard’s Roost, and Lookout Spur. The major hiking trails are shown on the map in colors indicated in the legend. Find the trail that best suits your interest, time available, and level of exertion. Besides the Loop Trail, there are alternative loop options using the Echo Canyon and Turkey Pass trails.

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References

s

The following resources were consulted in some manner in the development of this book. The list is by no means exhaustive; an extensive body of research is available that is relevant to this work. A number of sources used in the research for this book were found in collections held at various libraries of the University of Texas, including the University of Texas Center for American History, the Perry-Castañeda Library Map Collection, and the Harry Ransom Center.

Printed Publications History and Archaeology Assad, C., and D. R. Potter. “An Intensive Archaeological Survey of Enchanted Rock State Natural Area, Gillespie and Llano Counties, Texas.” Center for Archaeological Research, Archaeological Survey Report 84. San Antonio: University of Texas, 1979. Biggers, Don. German Pioneers in Texas: A Brief History of Their Hardships, Struggles, and Achievements. Fredericksburg, Tex.: Fredericksburg Publishing Co., 1925; reprint, Austin: Eakin, 1983. Goetzmann, William, and Glyndwr Williams. The Atlas of North American Exploration. Austin: University of Texas, 1966. ———. The Atlas of North American Exploration. Norman: University of Oklahoma Press, 1992. Greer, J. W. “An Archaeological Reconnaissance of the Enchanted Rock Area of Llano and Gillespie Counties, Central Texas.” In

Enchanted Rock: A Natural Area Survey 14. Austin: Lyndon B. Johnson School of Public Affairs, University of Texas, 1979. Kotter, Steven M. Archeological Assessments at 41GL57 and 41GL91, Enchanted Rock State Natural Area, Gillespie County, Texas. Austin: Prewitt and Associates, 1980. Kowert, Nancy. Enchanted Rock: A Landmark on the Trail. Fredericksburg, Tex.: Fredericksburg Publishing Co., 1963. McGuire, James Patrick. Hermann Lungkwitz: Romantic Landscapist on the Texas Frontier. Austin: University of Texas Press, 1983. Moss, Charles, and Ruth Moss. Facts and Fiction About the Enchanted Rock. 1956. Reid, Samuel C. The Scouting Expeditions of McCulloch’s Texas Rangers. Philadelphia: J. E. Potter and Co., 1885. Rossman, Charles. Enchanted Rock: Views of a Texas Batholith. Austin: Duncan and Gladstone, 1985. Williams, John. On Your Way Up: A Trail Guide to the Top of Enchanted Rock. Austin: Texas Parks and Wildlife Dept., 1994.

Geology, Weathering and Erosion, and Weather Barnes, Virgil E., W. C. Bell, S. E. Calbaugh, P. E. Cloud Jr., R. V. McGehee, P. U. Rodda, and Keith Young. Geology of the Llano Region and Austin Area: Field Excursion, Guidebook 13. Austin: Bureau of Economic Geology, University of Texas, 1972. Bomar, George W. Texas Weather. Austin: University of Texas Press, 1995.

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ref erences

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Dalziel, Ian W., and Lisa M. Gahagan. The Making of Texas. Poster. Austin: Jackson School of Geosciences, University of Texas Institute for Geophysics, 1999. Dalziel, Ian W., Sharon Mosher, and Lisa M. Gahagan. “Laurentia-Kalahari Collision and the Assembly of Rodinia.” Journal of Geology 108, no. 9 (2000): 499–513. Ewing, Thomas E. The Tectonic Framework of Texas. Austin: Bureau of Economic Geology, University of Texas, 1991. ———. The Tectonic Map of Texas. Austin: Bureau of Economic Geology, University of Texas, 1991. Fenneman, N. M. Physiography of Western United States. New York: McGraw-Hill, 1931. Geological Society of America. “Guide to the Precambrian Geology of the Eastern Llano Uplift, Central Texas.” Field Trip Guide for the Geological Society of America 30. Austin: University of Texas, 1996. Hamblin, Kenneth W. The Earth’s Dynamic Systems, 4th ed. Minneapolis: Burgess Publishing, 1985. Hejl, H. R. Jr., Raymond M. Slade, Jr., and M. E. Jennings. “Floods in Central Texas, December 1991.” Water Resources Investigation Report 95-4289. U.S. Geological Survey, 1991. Hutchinson, Robert M. “Enchanted Rock Pluton, Llano and Gillespie Counties.” Dissertation, University of Texas at Austin, 1953. ———. Enchanted Rock Batholith (Map). Austin: Bureau of Economic Geology, University of Texas, 1956. Kastning, Ernst H. Jr. “Geological Environment of the Enchanted Rock Area.” In Enchanted Rock: A Natural Area Survey 14. Austin: Lyndon B. Johnson School of Public Affairs, University of Texas, 1979. Kious, J., and Robert I. Tilling. This Dynamic Earth. Washington, D.C.: U.S. Geological Survey, 1996. Long, Leon. Geology, 13th ed. Austin: Pearson Custom Publishing, 2007. Lutgens, Frederick K., Edward J. Tarbuck, and Dennis Tasa. The Atmosphere: An Introduction to Meteorology, 8th ed. New York: Prentice Hall, 2001.

262

Morton, J., and L. Long. “Rb-Sr Ages of Glauconite Recrystallization: Dating Times of Regional Emergence Above Sea Level.” Journal of Sedimentary Research 54, no. 2 (June 1984): 495–506. Mosher, Sharon. “Tectonic Evolution of the Southern Laurentian Grenville Orogenic Belt.” Geological Society of America Bulletin 110, no. 11 (Nov. 1998): 1357–1375. Petersen, James. Enchanted Rock State Natural Area: A Guide to the Landforms. San Marcos, Tex.: Terra Cognita Press, 1984. Reed, Robert. “Emplacement and Deformation of Late Syn-Orogenic, Grenville-age Granites in the Llano Uplift, Central Texas.” Thesis, University of Texas at Austin, 1999. Reese, Joseph F., and Sharon Mosher. “Kinematic Constraints on Rodinia Reconstructions from the Core of the Texas Grenville Orogen.” Journal of Geology 112 (2004): 185–205, 278–291. Reese, Joseph F., Sharon Mosher, James Connelly, and Robert Roback. “Mesoproterozoic Chronostratigraphy of the Southeastern Llano Uplift, Central Texas.” Geological Society of America Bulletin 112, no. 2 (Feb. 2002). Slade, Raymond M. Jr. “Large Rainstorms Along the Balcones Escarpment in Central Texas.” Pp. 15-20 in The Balcones Escarpment: Geology, Hydrology, Ecology, Patrick L. Abbott and C. M. Woodruff, eds. San Antonio: Geological Society of America, 1986. Spearing, Darwin. Roadside Geology of Texas. Missoula: Mountain Press Publishing Co., 1991. Texas Department of Economic Geology. Geological Map of Texas. Austin: University of Texas, 1992. United States Geological Survey. “Divisions of Geologic Time: Major Chronostratigraphic and Geochronologic Units, Fact Sheet.” USGS, 2007. Woodruff, C. M. Llano Uplift and Hill Country: A Geological Excursion into Central Texas. Guidebook, Sesquicentennial Geological Field Trip, C. M. Woodruff, 1985.

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Plants and Animals Abbott, John C. Dragonflies and Damselflies of Texas and the South-Central United States. Princeton, N.J.: Princeton University Press, 2005. Ajilvsgi, Geyata. Wildflowers of Texas. 2nd ed. Bryan, Tex.: Shearer Publishing, 2003. Behler, John L., and F. Wayne King. The Audubon Society of North America Field Guide to North American Reptiles and Amphibians. New York: Knopf, 1979. Blair, W. F. “The Biotic Provinces of Texas.” Texas Journal of Science 2, no. 1 (1950): 93–117. Brodo, Irwin M., Sylvia Duran Sharnoff, and Stephen Sharnoff. Lichens of North America. New Haven: Yale University Press, 2001. Bull, John, and John Farrand Jr. National Audubon Society Field Guide to North American Birds, Eastern Region. New York: Knopf, 1994. Butterwick, Mary. “A Survey of the Flora of Enchanted Rock and Vicinity, Llano and Gillespie Counties, Texas.” In Enchanted Rock: A Natural Area Survey 14. Austin: Lyndon B. Johnson School of Public Affairs, University of Texas, 1979. Capinera, John L., Ralph D. Scott, and Thomas J. Walker. Field Guide to the Grasshoppers, Katydids, and Crickets of the United States. Ithaca, N.Y.: Cornell University Press, 2006. Cox, Paul W., and Patty Leslie. Texas Trees: A Friendly Guide. San Antonio, Tex.: Corona Publishing Co., 1988. Diggs, George M., Barney L. Lipscomb, and Robert J. O’Kennon. Shinners and Mahler’s Illustrated Flora of North Central Texas. Fort Worth: Botanical Research Institute of Texas, 1999. Dixon, James R., and John E. Werler. Texas Snakes: A Field Guide. Austin: University of Texas Press, 2005. Dunn, Jon, and Jonathon Alderfer. Field Guide to the Birds of North America, 2nd ed. Washington, D.C.: National Geographic Society, 1996 Enquist, Marshall. Wildflowers of the Texas Hill Country. Austin: Lone Star Botanical, 1987.

Garrett, Howard, and C. Malcolm Beck. Texas Bug Book: The Good, the Bad, and the Ugly. Austin: University of Texas Press, 2005. Gould, Frank W. Common Texas Grasses: An Illustrated Guide. College Station: Texas A&M University Press, 1978. ———. Texas Plants: A Checklist and Ecological Summary. College Station: Texas Agricultural Experiment Station, Texas A&M University, 1975. Helfer, Jacques R. How to Know the Grasshoppers, Crickets, Cockroaches, and Their Allies. Dubuque, Iowa: Dover, 1963. Jackman, John. A Field Guide to Spiders and Scorpions of Texas. Houston: Gulf Publishing, 1997. Kutac, Edward A., and S. Christopher Caran. Birds and Other Wildlife of South Central Texas. Austin: University of Texas Press, 1994. Laessoe, Thomas, and Gary Lincoff. Mushrooms. New York: DK Adult, 1998. Levi, Herbert W., and Lorna R. Levi. Spiders and Their Kin. Golden Guide. New York: St. Martin’s Press, 2001. Little, Elbert L. The Audubon Society Field Guide to North American Trees, Eastern Edition. New York: Knopf, 1980. ———. The Audubon Society Field Guide to North American Trees, Western Edition. New York: Knopf, 1980. Lockwood, Mark W. Basic Texas Birds. Austin: University of Texas Press, 2007. ———. Birds of the Texas Hill Country. Austin: University of Texas Press, 2001. Loflin, Brian, and Shirley Loflin. Grasses of the Texas Hill Country. College Station: Texas A&M University Press, 2006. Loughmiller, Campbell, and Lynn Loughmiller. Texas Wildflowers. Revised ed. updated by Damon Waitt. Austin: University of Texas Press, 2006. Lyndon B. Johnson School of Public Affairs. Preserving Texas’ Natural Heritage. Policy Research Project Report 31. Austin: University of Texas, 1978. Metzler, Susan, and Van Metzler. Texas Mushrooms. Austin: University of Texas Press, 1992.

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Milne, Lorus, and Margery Milne. The Audubon Society of North America Field Guide to North American Insects and Spiders. New York: Knopf, 1980. Mitchell, Robert T., Herbert S. Zim, and Andre Durenceau. Butterflies and Moths. Golden Guide. New York: St. Martin’s Press, 2001. National Health and Environmental Effects Research Laboratory. Level III Ecoregions of Texas. Revised. U.S. Environmental Protection Agency, 2000. Natural Resource Program. Birds of Enchanted Rock State Natural Area: A Field Checklist. Austin: Texas Parks and Wildlife Dept., 2001. Omernik, Jim. Level III Ecological Regions of North America. Map. Washington, D.C.: Environmental Protection Agency, 1987. Otte, Daniel. The North American Grasshoppers, Vol. 1, Acrididae: Gomphocerinae and Acridinae. Cambridge, Mass.: Harvard University Press, 1981. ———. The North American Grasshoppers, Vol. 2, Acrididae: Oedipodinae. Cambridge, Mass.: Harvard University Press, 1985. Pyle, Robert Michael. The Audubon Society Field Guide to North American Butterflies. New York: Knopf, 1981. Robbins, Chandler S., Bertel Bruun, Herbert S. Zim, and Arthur Singer. Birds of North America: A Guide to Field Identification. Golden Guide. New York: St. Martin’s Press, 2001 Smith, Hobart M., Edmund Brodie, and Sy Barlowe. Reptiles of North America: A Guide to Field Identification. Golden Guide. New York: St. Martin’s Press, 2001 Udvardy, Miklos D. F. National Audubon Society Field Guide to North American Birds, Western Region. New York: Knopf, 1994. Wagner, David L. Caterpillars of Eastern North America. Princeton, N.J.: Princeton University Press, 2005. Weniger, Del. Cacti of Texas and Neighboring States: A Field Guide. Austin: University of Texas Press, 1984. Whitaker, John O. Jr. The Audubon Society Field Guide to North American Mammals. New York: Knopf, 1996.

Whitehouse, Eula. “Plant Succession on Central Texas Granite.” Ecology 14, no. 4 (1933). ———. The Ecology of Enchanted Rock Vegetation. Thesis, University of Texas at Austin, 1931. Wildlife Division. The Vegetation Types of Texas. Map. Austin: Texas Parks and Wildlife Department, 1984. Zim, Herbert S., and Clarence Cottam. Insects. Golden Guide. New York: St. Martin’s Press, 2001.

Online Resources Web site links are subject to change. These are the sites that were useful during the research for this book.

History and Archaeology Early Spanish Expeditions: www.floridahistory. com Enchanted Rock History: www.texfiles.com General Information: www.wikipedia.com Gillespie County Information and History: www.gillespiecounty.org Llano Uplift Archaeological Society (LUAS): www.llanotx.com/luas.html Moss Family Information: www.centuryranchlodging.com/ourHistory.html National Natural Landmarks Information: www.nature.nps.gov/nnl Texas Beyond History: www.texasbeyondhistory.net Texas Historic Sites: http://atlas.thc.state.tx.us Texas History Publications: www.tsha.utexas. edu/publications/journals/online Texas History, Handbook of Texas Online: www.tsha.utexas.edu/handbook/online

Geology, Weathering and Erosion, and Weather Climate Data (National Climatic Data Center): www.ncdc.noaa.gov/oancdc.html Climate History (U.S. Historical Climatology Network): www.ncdc.noaa.gov/oa/climate/ research/ushcn/ushcn.html

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Earth Observations (NASA): www.earthobservatory.nasa.gov Edwards Aquifer Formation: www.edward saquifer.net Great Plains: www.lib.ndsu.nodak.edu/govdocs/text/greatplains/text.html Lakes of Central Texas and Other Water Information: www.lcra.org National Climate Data Center (including precipitation from USHCN): www.ncdc.noaa. gov Natural Regions (Texas Parks and Wildlife): www.tpwd.state.tx.us/publications/ pwdpubs/pwd_bn_w7000_0120 Physiographic Regions (U.S. Geological Survey): http://tapestry.usgs.gov Rob’s (Reed) Granite Page (Central Texas and Enchanted Rock): http://uts.cc.utexas. edu/~rmr Scotese Paleo-globe Diagrams and Animations: www.scotese.com Soils: http://soils.usda.gov Soils: www.tx.nrcs.usda.gov/soil/index.html Texas Geology and Other Information: www. lib.utexas.edu/geo “Texas through Time” Plates Project (University of Texas Institute for Geophysics): www. ig.utexas.edu/research/projects/plates Weather (National Weather Service Online School for Weather, Jetstream): www.srh. noaa.gov/jetstream/index.htm Weather Data, Central Texas (National Weather Service Forecast Office for Austin and San Antonio, Texas): www.srh.noaa.gov/ ewx Weather Data, Central Texas (Southeast Regional Climate Center): http://cirrus.dnr. state.sc.us/cgi-bin/sercc/cliGCStT.pl?tx3329 and tx5272 Weather Information, General: www.nws.noaa. gov

Plants and Animals Amphibian Distributions: www.pwrc.usgs.gov/ ARMIatlas Bugs: www.bugguide.net Butterflies and Moths: www.butterfliesandmoths.org

Butterflies and Moths: www.nearactica.com Caterpillars: www.npwrc.usgs.gov/resource/ insects/cateast/index.htm Dragonflies and Damselflies: http://odonatacentral.bfl.utexas.edu Endemics of Texas: www.csdl.tamu.edu/FLORA/endemics/endemic1.htm Frogs, Snakes, and Lizards of Texas: www. zo.utexas.edu/learning/txherps Grasshoppers (Oklahoma): www.opsu.edu/ UnivSchools/ScienceMathNurs/PlantsGrassh/grasshoppers/default.html Grasshoppers (Wyoming): www.sdvc.uwyo. edu/grasshopper/ghatlas.htm Grasshoppers, Crickets, Katydids: http://osf2. orthoptera.org/HomePage.aspx Grasshoppers: http://fs-syd2.sidney.ars.usda. gov/grasshopper Integrated Taxonomic Information System: www.itis.gov Lichens: www.lichen.com Mammals: www.nsrl.ttu.edu/tmot1/contents. html Monarch Watch: www.monarchwatch.org Monarchs in Texas: www.tpwd.state.tx.us/ learning/texas_nature_trackers/monarch/ migration/us_flyways.phtml Moths: http://mothphotographersgroup. msstate.edu/MainMenu.shtml Moths: www.origins.tv/entomology/moths.htm Owls, including calls: www.owlpages.com Plants (Central Texas): www.bio.utexas.edu/ courses/bio406d Plants (Central Texas): www.sbs.utexas.edu Plants (Florida): www.plantatlas.usf.edu/default.asp Plants (Kansas): www.lib.ksu.edu/wildflower Plants (Lady Bird Johnson Wildflower Center): www.wildflower.org Plants (Missouri): www.missouriplants.com Plants (Texas): www.csdl.tamu.edu/flora/gallery.htm Plants of Northern Texas: www.noble.org/we bapps/plantimagegallery/Index.aspx Plants, General Information: http://plants. usda.gov Plants, General Information: www.efloras.org Singing Insects Guide (crickets, katydids, cicadas): http://buzz.ifas.ufl.edu/584pf2.htm

ref erences

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Texas Parks Bird, Mammal, and Bug Tracking Projects: www.tpwd.state.tx.us/learning/ texas_nature_trackers

Climbing Climbing at Enchanted Rock: www.erockon line.com Central Texas Mountaineers: www.ctmrocks. com Climbing Route Information: www.rockclimb ing.com

Maps Historic Maps: www.davidrumsey.com Mapping Software (ArcView): www.esri.com Mapping Software (Globalmapper): www. globalmapper.com National Atlas, United States Geological Survey: www.nationalatlas.gov National Map Project: www.nationalmap.gov Texas County Maps: http://txdot.lib.utexas.edu Texas General Land Office (maps, grants, patents): www.glo.state.tx.us Texas Maps (University of Texas, Perry-

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Castañeda Collection): www.lib.utexas. edu/maps/texas.html; www.lib.utexas.edu/ maps/atlas_texas; www.lib.utexas.edu/geo/ fulltext.html#maps Texas Natural Resources Information System (DEMs and Satellite Imagery): www.tnris. state.tx.us; www.tnris.org Texas Parks Maps: www.tpwd.state.tx.us/ landwater/land/maps/gis/map_downloads; www.tpwd.state.tx.us/publications/ pwdpubs/media/park_maps/pwd_mp_ p4507_119c.pdf United States Geological Survey (digital mapping data): http://seamless.usgs.gov

Organizations Lower Colorado River Authority: www.lcra. org Friends of Enchanted Rock (FoER): www. friendsofenchantedrock.org Central Texas Climbing Committee: http:// www.huecotanks.com/ctcc.htm Nature Conservancy: www.nature.org/ wherewework/northamerica/states/texas

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Illustration Sources

s

Many of the nonphotographic illustrations in this book were based on existing illustrations, often drawing from more than one source for a single illustration. “NMP” at the end of a source note indicates that the background map for the illustration was modified from a map courtesy of the National Map Project, www. nationalmap.gov. Unless otherwise indicated, the photographs in the book were captured by the author at Enchanted Rock SNA. p. vi Screaming Rock: Photograph with permission of Windflower Waters, from Enchanted Rock SNA. p. 9 Stone Points: Modified from an illustration in A Field Guide to Stone Artifacts of Texas Indians, 2nd ed., p. 52, courtesy of Ellen Sue Turner and Thomas R. Hester of the Texas Archaeological Society. p. 9 Pictograph: Photograph by the author from Devils River State Natural Area. p. 12 Spanish Exploration Routes: Routes from map in Perry-Castañeda Library On-line Map Collection, University of Texas, Austin, from data originally from Goetzmann and Williams, Atlas of North American Exploration. NMP p. 14 Native American Migrations: Modified

from map courtesy Perry-Castañeda Library On-line Map Collection, University of Texas, Austin, originally from the Atlas of Texas, University of Texas at Austin, Bureau of Business Research, 1976. NMP p. 16 Spanish Missions and Presidios: Modified map courtesy Perry-Castañeda Library Online Map Collection, University of Texas, Austin, originally from the Atlas of Texas, University of Texas at Austin, Bureau of Business Research, 1976. Also from map of Spanish missions at www.texasalmanac. com/history/highlights/spanish-missions/. NMP p. 23 Republic of Texas: Map courtesy David Rumsey Map Collection, www.davidrum sey.com. p. 27 Central Texas Granite: Granite images taken by author; polished samples provided courtesy Cold Springs Granite Co., Llano, Texas. p. 28 Martínez Land Grant: Modified map courtesy Texas General Land Office, Archives and Records. p. 29 Hermann Lungkwitz Painting, 1856: Courtesy Witte Museum, San Antonio, Texas. pp. 40–41 Geologic Time Chart: Names and time boundaries from U.S. Geological Survey online publication, “Divisions of Geologic Time,” at http://pubs.er.usgs.gov.

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p. 42 Llano Region Bluebonnets: Photographed by the author east of Llano, Texas, along Highway 71. p. 43 Mesozoic and Cenozoic Features: Period features from Barnes et al., Geology of the Llano Region and Austin Area. Granite coastal sediment deposits modified after map at Enchanted Rock SNA Visitor Center. NMP p. 44 Deposit Timeline: Constructed from images provided courtesy Dr. Leon Long, Jackson School of Geosciences, University of Texas Institute for Geophysics, Austin, based on Morton and Long, “Rb-Sr Ages of Glauconite Recrystallization.” p. 44 Cretaceous Seaway: Modified from diagram provided courtesy Dr. Leon Long, Jackson School of Geosciences, University of Texas Institute for Geophysics, Austin. p. 47 Stratigraphic Column, Eastern Llano Region: Modified from diagram provided courtesy Dr. Leon Long, Jackson School of Geosciences, University of Texas Institute for Geophysics, Austin. p. 48 Plate Tectonics and Subduction: After diagrams in Hamblin, Earth’s Dynamic Systems, p. 338; in Long, Geology; and in Kious and Tilling, This Dynamic Earth. p. 50 Pangaea: Modified from image provided courtesy Jackson School of Geosciences, University of Texas Institute for Geophysics, “Texas through Time” Plates Project, www.ig.utexas.edu/research/projects/plates; originally from the poster by Dalziel and Gahagan, The Making of Texas. p. 51 Paleozoic Features: Features from Barnes et al., Geology of the Llano Region and Austin Area. NMP p. 52 Horst and Graben Terrain: Modified from images provided courtesy Dr. Leon Long,

Jackson School of Geosciences, University of Texas Institute for Geophysics, Austin. p. 52 Cross Section, Balcones Fault to Eastern Llano Region: Modified from map in Barnes et al., Geology of the Llano Region and Austin Area. p. 54 Cross Sections, Llano Region: Seamless DEM maps courtesy United States Geological Survey. Base map and elevations modified from information generated by GlobalMapper, Version 8. p. 55 Surface Rock in the Llano Region: Modified from “Geologic Map of Texas,” Virgil Barnes, Project Supervisor, 1992. Digital Raster Graphics, Texas Natural Resources Information Systems. Age data courtesy Dr. Sharon Mosher, Jackson School of Geosciences, University of Texas Institute for Geophysics, Austin. Batholith names from data provided by multiple sources. p. 56 A Batholith and Associated Features: After diagrams in Hamblin, Earth’s Dynamic Systems, p. 84, and in Long, Geology, courtesy Dr. Leon Long, Jackson School of Geosciences, University of Texas Institute for Geophysics, Austin. p. 63 Rodinia: Modified from diagram in Dalziel et al., “Laurentia-Kalahari Collision and the Assembly of Rodinia.” p. 64 Southern Continent Approaches Texas: Modified from image in Mosher, “Tectonic Evolution of the Southern Laurentian Grenville Orogenic Belt.” p. 65 Texas Coastline Profile: Modified after diagram provided courtesy Dr. Sharon Mosher, Jackson School of Geosciences, University of Texas Institute for Geophysics, Austin. p. 66 Rock Domains: Domain information derived from data provided by Dr. Sharon Mosher, Jackson School of Geosciences, University of Texas Institute for Geophysics,

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Austin. Digital Raster Graphics, Texas Natural Resources Information System. p. 67 Llanite: Photograph by the author, from the Llanite Dike along Highway 29 north of Llano, Texas. p. 78 Stream Terraces: Based on diagrams in Hamblin, Earth’s Dynamic Systems, p. 194. p. 78 Braided Stream: Photograph by the author, from the Sandy Creek bridge crossing along Highway 71. p. 81 Jointed Zones: Satellite imagery courtesy Texas Natural Resources Information System. Fracture zone locations from Reed, “Emplacement and Deformation of Late Syn-Orogenic, Grenville-age Granites.” p. 82 Exfoliation Dome Cross Section: Photograph by the author from near the Merced River, Yosemite National Park, California. p. 82 Half-Dome, Yosemite: Photograph by the author, from near the Merced River, Yosemite National Park, California. p. 94 Temperature (Monthly): Average high and low temperatures from the Climate (Local Data) Web pages for the National Weather Service Forecast Office for Austin and San Antonio, Texas. Record highs and lows from Southeast Regional Climate Center. p. 95 Sunshine Percentage: Modified from map created by NOAA’s National Climatic Data Center (NCDC), http://www.ncdc.noaa. gov. NMP p. 96 Precipitation and Evaporation: Modified from map produced as a collaboration between The PRISM Group, Oregon State University, http://www.prism.oregonstate. edu, with funding from the National Resources Conservation Service, the USDA Forest Service, the NOAA Office of Global Programs, and others. Evaporation data

from Lower Colorado River Authority Planning Group Report, LCRAPG Adopted Report, December 2000. NMP p. 97 Rainfall (Monthly): Precipitation data from Climate (Local Data) Web pages for the National Weather Service Forecast Office for Austin and San Antonio, Texas. NMP p. 104 Air Masses: Information modified from diagram at National Weather Service Online School for Weather, Jetstream. NMP p. 105 Circulation Cells: Modified from diagram at www.ux1.eiu.edu/~jpstimac/1400/ fronts.html; originally from Lutgens et al., Atmosphere, Figure 7.25. Jet stream locations modified from diagram at National Weather Service Online School for Weather, Jetstream. Trade winds modified from diagrams at NASA’s Earth Observatory Web site and from other sources. p. 106 Stable and Unstable Air: Modified from Lutgens et al., Atmosphere, Figures 4.13 and 4.16, and from a diagram at National Weather Service Online School for Weather, Jetstream. p. 108 Fronts and Dry Line: Air mass locations modified from diagram at National Weather Service Online School for Weather, Jetstream. Precipitation and front locations from data at www.weather.com, March 9, 2006. NMP p. 109 Warm Front Cross Section: Modified from diagram at www.ux1.eiu. edu/~jpstimac/1400/fronts.html, originally from Lutgens et al., Atmosphere, Figure 9.7. p. 109 Cold Front Cross Section: Modified from diagram at www.ux1.eiu. edu/~jpstimac/1400/fronts.html, originally from Lutgens et al., Atmosphere, Figure 9.6. p. 111 Dry Line Cross Section: NMP p. 118 Annual Rainfall at Llano, Texas: Data from

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U.S. Historical Climatology Network for Llano, Texas. p. 118 Selected Historic Floods Along Balcones Escarpment: Rainfall event data for 1998 and 2002 from Weather Events Web pages of National Weather Service Forecast Office for Austin and San Antonio, Texas. Rainfall event data for 1991 from Hejl et al., “Floods in Central Texas, December 1991,” Figure 1. Other rainfall event data from Slade, “Large Rainstorms Along the Balcones Escarpment in Central Texas.” NMP p. 124 Physiographic Regions: Modified from maps courtesy United States Geological Survey, “The North America Tapestry of Time and Terrain,” based on work originally by N. M. Fenneman. p. 125 Natural Regions of Texas: Modified from map courtesy Perry-Castañeda Library Online Map Collection, University of Texas, Austin; originally from Lyndon B. Johnson School of Public Affairs, Preserving Texas’ Natural Heritage. NMP p. 126 Vegetative Cover: Modified from map courtesy Perry-Castañeda Library On-line Map Collection, University of Texas, Austin;

originally from Wildlife Division, Vegetation Types of Texas. p. 128 Ecoregions: Modified from maps courtesy Perry-Castañeda Library On-line Map Collection, University of Texas, Austin; originally from Blair, “Biotic Provinces of Texas,” and National Health and Environmental Effects Research Laboratory, Level III Ecoregions of Texas. NMP p. 131 Plant Zones at Enchanted Rock SNA: Plant zones based on delineation from Whitehouse, “Plant Succession on Central Texas Granite,” modified by Butterwick, “A Survey of the Flora of Enchanted Rock.” Trail locations and elevations modified from Enchanted Rock SNA park map from Texas Parks and Wildlife. p. 211 Monarch Butterfly Flyway: Modified from online monarch migration maps from Texas Parks and Wildlife. p. 258 Satellite imagery courtesy Texas Natural Resources Information System. Trail locations and elevations modified from Enchanted Rock SNA park map from Texas Parks and Wildlife, satellite imagery, and GPS readings.

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a ppendi x a

Species Index

s Abaeis nicippe, 214 Abutilon friticosum, 171 Acalypha gracilens, 164 Acalypha ostryifolia, 164 Acanthaceae family, 255 Acanthocephala femorata, 243 Acanthocephala terminalis, 243 Acarospora sp., 132 Accipitridae family, 200 Achalarus casica, 212 Achillea millefolium var. occidentalis, 161 Acmaeodera ornata, 239 Acontia aprica, 223 Acontia tetragona, 223 Acrididae family, 229 Acris crepitans blanchardi, 206 Acrosternum hilare, 244 Addler’s tongue, 256 Adelpha bredowii eulalia, 216 Adephaga suborder, 239 Aesculus glabra var. arguta, 149, 165, 186 Aeshnidae family, 224 agarito, 140, 148, 153, 169, 183 Agavaceae family, 160, 174, 255 agave family, 160, 174 Agelenidae family, 248 Agraulis vanillae, 216 Aimophila ruficeps, 201 Alabama lipfern, 174, 175 Alleculinae subfamily, 241 Allium canadense var. fraseri, 165, 186 Allium drummondii, 156 Allium elmendorfii, 256

Allograpta sp., 235 Aloysia gratissima, 150, 167 Alphia sp., xvi Alternanthera caracasana, 160 Alypia octomaculata, 223 amaranth family, 160 amaranth flower, 161 Amaranthaceae family, 160 amberique bean, 152, 155, 185 Amblytropidia mysteca, 230 Ambrosia psilostachya, 168, 182 American bird grasshopper, 229 American bumble bee, 236 American elm, 137, 139, 147, 150 American finch, 202 American germander, 153, 156 American lady, 138, 217 American nightshade, 167, 188 American pillwort, 256 American pokeweed, 134, 165, 187 American rubyspot, 227 American snout, 211, 217 American tripogon, 87, 132, 179, 256 American vulture family, 200 Ammophila sp., 236 Anacamptodes dataria, 220 Anacardiaceae family, 147, 151, 161, 182 Anaea andria, 212, 216 Anaea troglodyta, 216 Anatidae family, 200 Anavitrinella pampinaria, 220 Anax sp., 224 Andropogon glomeratus, 176

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Anemone berlandieri, 157, 166, 187 annual rabbit’s foot grass, 178 annual wild buckwheat, 153, 166 Anseriformes order, 200 ant, 236, 245 antelope horns, 153, 182 ant family, 245 Anthanassa texana, 216 Anthocharis midea, 215 Anthracinae subfamily, 233 antlion and lacewing order, 246 antlion family, 246 antlion genus, 246 Aon noctuiformis, 222 Aphanostephus skirrhobasis, 161 aphid family, 243 Aphididae family, 243 Apiaceae famly, 161, 182 Apidea family, 236 Apinea subfamily, 236 Apini tribe, 236 Apiomerus sp., 244, 245 Apis mellifera, 236 Apoidea superfamily, 236 Arabis petiolaris, 154, 183, 184 Araneae order, 248 Araneidae family, 248 Araneus bicentenarius, 248 Araneus detrimentosus, 248 Archilestes grandis, 228 Archilochus alexandri, 200, 201 Arctiidae family, 221 Arethaea grallator, 231 Argemone albiflora, 165 Argia fumipennis violacea, 227

in dex

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Argia immunda, 227 Argia moestra, 227 Argia nahuana, 227 Argia plana, 227 Argia sedula, 227 Argiope aurantia, 248 Argiope trifasciata, 248 Arilus cristatus, 245 Aristida sp., 176 Aristolochia coryi, 151, 159 Aristolochiaceae family, 151, 159, 255 Arizona sister, 141, 211, 216 Armadillidiidae family, 246 Armadillidium vulgare, 246 armadillo family, 197 Arphia conspersa, 230 Arphia simplex, 230, 231 Arphia sp., 141 Artemisia ludoviciana, 161 Ascalaphidae family, 246 Asclepiadaceae family, 151, 182 Asclepias asperula, 161, 182 Asclepias oenotheroides, 161 Ashe juniper, 140, 142, 148, 184 ash-throated flycatcher, 203 Asilidae family, 233 assassin bug family, 244 assassin bug genus, 244, 235 astarte prominent, 221 Asteraceae family, 147, 153, 159, 161, 168, 182, 255 aster genus, 162 Asterocampa celtis, 216 Asterocampa leilia, 216 Astragalus crassicarpus, 256 Astragalus nuttallianus var. austrinus, 152, 155, 185, 256 Astrolepus sinuata, 175 Atalopedes campestris, 214 Atlides halesus, 212 Augochlorini tribe, 236 Augochloropsis sp., 236 Avena fatua, 176 Aztec dancer, 227 Aztec range grasshopper, 229, 231 baby blue eyes (flowering plant), 156 baccatalis moth, 219 Baccharis neglecta, 147, 162, 182

Bacopa monnieri, 167 bald eagle, 2 ball moss, 190 banded argiope, 248 banded pennant, 225 band-winged grasshopper family, 230 barberry family, 148, 169, 183 basin bellflower, 139, 143, 154, 255 basin sneezeweed, 132, 134, 142, 153, 168, 183 Battus philenor, 212 Batyle ignicollis, 240 beach groundcherry, 172, 188 bean family, 144 bearded flat sedge, 181 bearded swallowwort, 151, 161 bee and specid wasp superfamily, 236 beech family, 148, 171, 185 bee fly family, 233 bee fly genus, 233, 234 beetle order, 239 bellflower family, 151, 154, 159 beloved emarginea, 223 Berberidaceae family, 148, 169, 183 Berytidae family, 243 Bewick’s wren, 203 Bicyrtes sp., 236 big-flower bladderpod, 255 birthwort family, 151, 159 black-and-yellow argiope, 248 black-and-yellow lichen, 221 black-and-yellow mud dauber, 237 black-bellied whistling duck, 200 blackbird and oriole family, 202 black-chinned hummingbird, 199–201 black-crested titmouse, 202 black-eyed susan, 169 black-footed quillwort, 179 black-foot euphorbia, 256 blackjack oak, 94, 129, 134, 140, 142, 147, 148, 153, 171, 185 black saddlebags, 224, 226 black swallowtail, 211 black-tailed jackrabbit, 197 black vulture, 134, 199, 200 black widow, 248

black willow, 130, 137, 139, 150, 167, 188 bladderpod genus, 153, 170, 184 bladderwort family, 171 Blanchard’s cricket, 134, 137, 206, 207 Blechnaceae family, 175, 255 Blechnum occidentale, 175 blister beetle family, 241 blister beetle genus, 241 blowfly, 234 blowfly family, 234 bluebonnet. See Texas bluebonnet blue curls, 153, 156 blue dasher, 226 blue-gray gnatcatcher, 202 blue-ringed dancer, 227 blunt-lobed woodsia, 174, 175 blunt spike rush, 181 Boerhavia coccinea, 157 Bombini tribe, 236 Bombus pensylvanicus, 236 Bombyliidae family, 233 Boopedon gracile, 230 borage family, 162 Boraginaceae family, 162, 255 bordered patch, 216 bordered plant bug family, 244 bordered plant bug genus, 244 Bothriochloa ischaemum var. sonarica, 176 Bothriochloa saccharoides var. torreyana, 176 Bouteloua aristidoides, 176 Bouteloua curtipendula, 176 Bouteloua hirsuta, 176 Bouteloua rigidiseta, 177 boxwood leafroller, 219 Brachinecta sp., 132, 207 Brachymesia furcata, 225 Brachynemurus sp., 246 bracted passionflower, 152, 153, 172, 186 bracted zornia, 171 Brassicaceae family, 154, 162, 169, 183, 255 Brazilian free-tailed bat, 198 Brazos rock cress, 154, 183, 184, 255 Brechmorhoga mendax, 225 Brephidium exilis, 212

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bristlegrass, 137 bristleleaf dyssodia, 169 bristly sensitive brier, 151, 152, 153, 155 broad-banded grasshopper, 231 broadpod draba, 162, 183 broad-winged damselfly family, 227 Brochymena sp., 244 Bromeliaceae family, 190 bromeliad family, 190 Bromus catharticus, 177 Bromus japonicus, 177 brown panopoda, 222 brown recluse, 248, 250 brown-shaded gray moth, 220 brown winter grasshopper, 230 Bruner’s mantis, 242 Brunneria borealis, 242 Buchloe dactyloides, 177 Buckley’s yucca, 134, 142, 160, 174, 255 buckwheat family, 166, 187 Buddlejaceae family, 162 Buellia sp., 132 buffalobur nightshade, 137, 172, 188 buffalo gourd, 137, 151, 170, 184 buffalograss, 177 Bufonidae family, 207 Bufo woodhousii woodhousii, 207 Bulbostylis capillaris, 180 Bulia deducta, 222 bulia moth, 222 bumble bee tribe, 236 Buprestidae family, 239 bur clover, 170, 185 bur cucumber, 151, 163, 184 bush katydid genus, 232 bushy bluestem, 132, 139, 176 Buteo jamaicensis, 200 Buthidae family, 251 buttercup family, 157, 166, 172, 187 butterfly bush family, 162 butterfly pea, 149, 151, 152, 153, 155 buttonbush. See common buttonbush cacao family, 160 Cactaceae family, 154, 159, 170, 173, 184 cactus bug, 244

cactus coreid, 243 cactus family, 154, 159, 170, 173, 184 Caelifera suborder, 229 Caenurgina erechtea, 222 California cottontop, 177 Calliphoridae family, 234 Callirhoe involucrata, 156 Callophrys gryneus, 212 Callophrys henrici, 212 Calocoris barberi, 244 Caloplaca sp., 132 Calopterygidae family, 227 Calyptocarpus vialis, 168 Campanulaceae family, 151, 159, 255 Campanula reverchonii, 154 camphorweed, 169 Camponotus sp., 245 Canada wild onion, 132, 134, 153, 165, 179, 186, 211 Canada wild rye, 137, 177 canyon wren, 134, 199, 202 caper family, 162 Capparaceae family, 162 Caprifoliaceae family, 148, 163 Capsella bura-pastoris, 162, 184 Carabidae family, 239 cardinal family, 201 cardinal flower, 159 Cardinalidae family, 201 Cardinalis cardinalis, 201 Carduelis pinus, 202 Carduelis tristis, 202 Carduus nutans, 153 Carduus tenuiflorus, 153 Carex cephalophora, 180 Carex muehlenbergii, 180 Carolina canarygrass, 178 Carolina snailseed, 134, 151, 152, 165, 186 carpenter and leopard moth family, 218 carpenter ant genus, 245 carpenter bee family, 236 carrot family, 161, 182 Carya illinoinensis, 149, 186 Carya texana, 149, 159, 186 Caryophyllaceae family, 163, 184 Castilleja indivisa, 160 Catabena lineolata, 223 catbrier family, 152, 188

catclaw mimosa, 134, 148, 164, 185 cat family, 198 catfish, 208 Cathartes aura, 200 Cathartidae family, 200 Catherpes mexicanus, 202 catnip noseburn, 152, 164 Catocala maestosa, 223 cattail family, 180, 188 cattail genus, 137, 176, 179, 180, 189 cave swallow, 202 cedar elm, 94, 130, 137, 138, 140, 142, 147, 150, 153, 167, 189, 190 celery leaftier, 219 Celithemis eponina, 225 Celithemis fasciata, 225 Celtis laevigata, 150, 167, 189 Celtis laevigata var. reticulata, 150, 189 Cenchrus spinifex, 177 Centaurea melitensis, 168 Centrosema virginianum, 152, 155 Centruroides vittatus, 251 Cephalanthus occidentalis, 149, 166, 187 Cerambycidae family, 239 Cerambycinae subfamily, 240 Cerastium glomeratum, 163 Cercopidae family, 243 Cercyonis pegala, 212 Cervidae family, 197 Chaerophyllum tainturieri, 161 Chaetopappa asteroides, 162 chain fern family, 175 Chalybion sp., 237 Chamaesyce angusta, 256 Chamaesyce maculata, 164 Chamaesyce nutans, 164 Chamaesyce prostrata, 155, 164 Chamaesyce sp., 184 Charadriidae family, 200 Charadriiformes order, 200 Charadrius vociferus, 200 checkered setwing, 225 checkered skipper, 138 checkered white, 211, 215 Cheilanthes alabamensis, 175 Cheilanthes kaulfussi, 175, 257 Cheilanthes lindheimeri, 175 Cheilanthes tomentosa, 175 in dex

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Chelinidea vittiger, 243 Chenopodiaceae family, 163 Chenopodium berlandieri, 163 chipping sparrow, 199, 201 Chloris cucullata, 177 Chloris verticillata, 177 Chlosyne lacinia, 216 Chondestes grammacus, 201 Chortophaga viridifasciata, 231 Chrysomelidae family, 240 Chrysopidae family, 246 cicada family, 243 cicada killer, 236 Cicadidae family, 243 Cicindela sp., 239 Cicindelinae subfamily, 239 Ciconiiformes order, 200 Cirsium texanum, 153, 182, 183 Cissus incisa, 152 Cistaceae family, 170, 256 Cisthene tenuifascia, 221 citrine forktail, 228 claret-cup, 134, 153, 159, 173 clasping false pimpernel, 167 clasping Venus looking-glass, 151, 154 Clematis pitcheri, 152, 157, 187 Clematis texensis, 257 click beetle family, 240 clubtail dragonfly family, 225 Clusiaceae family, 170 Cnemidophorus gularis, 205 Cnidoscolus texanus, 164, 185 coastal water hyssop, 167 Coccinellidae family, 240 Cocculus carolinus, 152, 165, 186 Cochliomyia macellaria, 234 cocklebur, 169, 183 cockspur hawthorn, 166 Coenagrionidae family, 227 coffee-loving pyrausta, 219 Coleoptera order, 239 Colias eurytheme, 214, 215 collared and leopard lizard family, 204 Columbidae family, 200 Columbiformes order, 200 Columbina inca, 200 Columbina passerina, 200 Columbridae family, 205 columbrid snake family, 205 Comanche skimmer, 225 274

comb-clawed beetle subfamily, 241 Commelinaceae family, 154, 163, 256 Commelina erecta var. angustifolia, 154 common beebush, 135, 137, 150, 153, 167 common buckeye, 138, 211, 217 common burrower mayfly family, 242 common buttonbush, 130, 137, 139, 149, 153, 166, 187, 211 common checkered skipper, 215, 217 common chickweed, 163 common dandelion, 169, 183 common gray moth, 220 common ground dove, 200 common hoptree, 149, 166 common horehound, 165 common ivy treebine, 134, 151, 152 common least daisy, 139, 141, 153, 162 common mestra, 214, 215 common mullein, 172 common oak, 222 common purslane, 172 common sandbur, 137, 177 common sanddragon, 225 common six-weeks grass, 179 common sunflower, 2 common walking stick family, 247 common whitetail, 226 common wood nymph, 212 common woodsia, 134 Condylostylus sp., 234 Conopidae family, 234 Convolvulaceae family, 151, 155, 163, 256 Convolvulus equitans, 151, 155, 163 Cooperia drummondii, 165 Cooperia pedunculata, 165, 186 Copaeodes aurantiaca, 214 Copestylum mexicana, 235 Cophosaurus texanus, 204 Coragyps atratus, 200 coral snake family, 205 Coreidae family, 243

Coreopsis wrightii, 168, 183 Corydalis curvisiliqua ssp. curvisiliqua, 256 Corydalis sp., 171 Cory’s Dutchman’s pipevine, 151, 159, 255 Cossidae family, 218 cotton-flower, 161 cotton morning glory, 134, 151, 153, 155 cottonwood, 130, 137, 139 cowpen daisy, 137, 153, 169, 211 coyote, 197 crabapple genus, 158, 187 crablike spiny orb weaver, 249 Crabronidae family, 236 crab spider family, 250 Crambidae family, 218 crambid snout moth family, 218 crane fly genus, 235 Crassulaceae family, 170 Crataegus crus-galli, 149, 166 crevice spiny lizard, 134 crevice weaver spider family, 249 Croptilon hookerianum var. hookerianum, 168 Crotalus atrox, 205 Crotaphytidae family, 204 Crotaphytis collaris, 204 Croton capitatus, 164 croton genus, 153 Croton glandulosus, 164 Croton monanthogyrus, 164, 185 Croton texensis, 164 crow poison, 132, 134, 153, 165, 179 cuckoo and ani family, 200 Cuculidae family, 200 Cuculiformes order, 200 Cucullia laetifica, 223 Cucurbitaceae family, 151, 163, 170, 184 Cucurbita foetidissima, 151, 170, 184 Cudonigera houstonana, 218 Cupressaceae family, 148, 184 Curculionidae family, 240 Curculio sp., 240 curly-cup gumweed, 153, 168, 183 curve-pod corydalis, 256 Cuscutaceae family, 163 Cuscuta sp., 151, 163

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cut-leaf lacinata, 172 Cyclanthera dissecta, 151, 163, 184 Cyclophora nanaria, 220 Cydosia aurivitta, 223 cylinder flat sedge, 180 Cylindromyia sp., 235 Cylindropuntia leptocaulis, 170, 173 Cynanchum barbigerum, 151, 161 Cynanchum racemosum var. unifarium, 151, 161 Cynipidae family, 237 Cynipoidea superfamily, 237 Cynomya cadaverina, 234 Cyperaceae family, 180 Cyperus acuminatus, 180 Cyperus echinatus, 180 Cyperus esculentus, 181 Cyperus haspens, 181 Cyperus odoratus, 181 Cyperus retroflexus, 181 Cyperus retrorsus, 181 Cyperus rotundus, 181 Cyperus squarrosus, 181 Cyperus strigosus, 181 cypress family, 148, 180, 184 Cyrtacanthacridinae subfamily, 229 dainty sulphur, 211, 214 Dakota vervain, 158 Dalea nana, 185 Dalea tenuis, 256 Danaus glippus, 216 Danaus plexippus, 216 daring jumping spider, 250 darkling beetle family, 241 darkling beetle genus, 241 Dasymutilla sp., 245 Dasypodidae family, 197 Dasypus novemcinctus, 197 Daucus pusillus, 182 deer pea vetch, 152, 153, 155, 185 Dendrocygna autumnalis, 200 dense-flower bladderpod, 255 dense-tuft hair sedge, 132, 180 Descurainia pinnata, 170, 183 desert cloudywing, 212 desert firetail, 228 Desmia funeralis, 219 devil’s shoestring, 255 Diabrotica sp., 240

Diabrotica undecimpunctata, 240 diamond-backed water snake, 137 Diastictis fracturalis, 219 Diathrausta harlequinalis, 219 Dichanthelium acuminatum var. lindheimeri, 177 Dichondra recurvata, 151, 256 Dictyoptera order, 242 differential grasshopper, 229 Digitaria californica, 177 Digitaria ciliaris, 177 Digrammia cyda, 219 Dillen’s oxalis, 172 Diodia teres, 158 Diogmites sp., 233 Diospyros texana, 148, 163, 184 Diptera order, 233 Disholcaspis cinerosa, 237 diving beetle family, 239 dodder family, 163 dodder genus, 151, 163 Dolichopodidae family, 234 Dolomedes sp., 249 domesticated cat, 198 dotted blazing star, 154 dotted smartweed, 166 double-lined prominent, 221 double-striped bluet, 227 Draba platycarpa, 162, 183 drab brown wave, 220 Drasteria howlandi, 222 Drummond’s false pennyroyal, 156 Drummond’s phlox, 157 Drummond’s rain lily, 97, 165 Drummond’s ruella, 255 Drummond’s skullcap, 139, 153, 156 Drummond’s wild garlic, 153, 156, 179 Dryopteridaceae family, 175 dry rock moss, 134, 193 dun skipper, 212 dusky dancer, 227 dwarf flameflower, 157 dwarf nana, 185 dwarf spike rush, 181 dwarf St. John’s-Wort, 170 dwarf tawny wave, 220 Dythemis fugax, 225

Dythemis velox, 225 Dytiscidae family, 239 earless, spiny, side-blotched, horned lizard family, 204 earth-boring dung beetle family, 240 eastern carpenter bee, 236 eastern collared, 134, 204 eastern cottontail, 197 eastern cottonwood, 149, 188 eastern fox squirrel, 197, 198 eastern gramagrass, 137, 179 eastern meadowlark, 202 eastern phoebe, 203 eastern pondhawk, 225 eastern ringtail, 225 eastern screech owl, 200 eastern yellowjacket, 238 Ebenaceae family, 148, 163 Ebony family, 184 Echinocereus coccineus var. coccineus, 159, 173 Echinocereus reichenbachii ssp. reichenbachii, 154, 173 Echinochloa colona, 177 Ecliminae subfamily, 234 Econista dislocaria, 220 Ectobiidae family, 242 Edwards Plateau cornsalad, 257 Edwards Plateau milkvetch, 256 Edwards Plateau spiderwort, 154, 256 Efferia sp., 233 egg-leaf skullcap, 139, 153, 156 eight-spotted forester, 223 Elachistidae family, 218 Elapidae family, 205 Elateridae family, 240 elbowbush, 149, 172, 186 Eleocharis obtusa, 181 Eleocharis parvula, 181 Eleodes sp., 241 Elmendorf ’s onion, 256 elm family, 150, 167, 189 Elymus canadensis, 177 Elymus virginicus, 177 Emarginea percara, 223 Emberizidae family, 201 Empidonax traillii, 203 empress leilia, 216 Enallagma basidens, 227 in dex

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Enallagma civile, 227 Engelmannia pinnatifida, 168 Engelmann’s daisy, 168 Ephemeridae family, 242 Ephemeroptera order, 242 Epicauta sp., 241 Eragrostis secundiflora, 177 Eragrostis sp., 177 Eragrostis superba, 177 Erigeron sp., 162 Erinnyis obscura, 221 Eriocaulon koernickianum, 257 Eriogonum annuum, 166 Eriogonum tenellum var. ramosissimum, 166, 257 Erioneuron pilosum, 177 Eristalinae subfamily, 234 Eristalini tribe, 234 Eristalis sp., 234 Erodium circutarium, 156 Erpetogomphus designatus, 225 Erynnis funeralis, 212 Erynnis horatius, 212 Erythemus simplicicollis, 225 Escarpment blackcherry, 257 Ethmia apicipunctella, 218 Ethmia semilugens, 218 Eubolina impartialis, 222 Euchlaena tigrinaria, 220 Euclea delphinii, 218 Eumenes sp., 237 Eumeninae subfamily, 237 Eupatorium havanense, 147, 162 Eupatorium serotinum, 162 Euphorbiaceae family, 152, 155, 163, 184, 256 Euphorbia denata, 164 Euphorbia marginata, 164, 185 Euphyes vestrius, 212 Euptoieta claudia, 216 Euschistus sp., 244 Eustixia pupula, 219 evening primrose family, 157, 172 eveningstar rain lily, 97 evergreen sumac, 134, 147, 182 Eve’s necklace, 148 Evolvulus alsinoides, 151, 155 Evolvulus sericeus, 151, 163 Exelis ophiurus, 220 Exoprosopa iota, 233 Exoprosopini tribe, 233 exposed bird-dropping moth, 276

223 eyebane, 164 Eysenhardtia texana, 148, 164, 185 Fabaceae family, 148, 152, 155, 159, 164, 185, 256 Fagaceae family, 148, 171, 185 fairy sword, 121, 134, 174, 175 falcate orangetip, 215 falcon and caracara family, 200 Falconiformes order, 200 false dayflower, 154, 256 false nut grass, 181 familiar bluet, 227, 228 Faronta diffusa, 223 Faronta rubripennis, 223 Felidae family, 198 Felis domesticus, 198 Feltia subterranea, 223 field cricket genus, 232 field sparrow, 202 fiery skipper, 138, 214 figwort family, 158, 160, 167, 172 filamentous green algae family, 193 Filistatidae family, 249 finch family, 202 fine-lined sallow, 223 fire ant, 245 fire-necked Batyle beetle, 240 fishing spider genus, 249 five-spotted hawk moth, 221 flameleaf sumac. See prairie flameleaf sumac flat-faced long-horned beetle subfamily, 240 fleabane, 137, 162 flesh fly family, 234 flesh fly genus, 234 flycatcher family, 203 fly order, 233 forage looper, 222 forest tent caterpillar, 221 Forestiera pubescens, 149, 172, 186 fork-tailed bush katydid, 231, 232 Formicidae family, 245 four o’clock family, 156 four-spotted bird-dropping moth, 223 four-striped leaftail, 225 fragrant flat sedge, 181

Fraxinus pennsylvanica, 149, 186 free-tailed bat family, 198 Fringillidae family, 202 Froelichia gracilis, 161 frogfruit, 167 frostweed, 137, 138, 153, 162 Fuirena simplex, 181 Fumariaceae family, 171, 256 fumewort genus, 153, 171 fumitory family, 171 funeral duskywing, 212 funnel web spider family, 248 Gaillardia pulchella, 159, 183 Galactia heterophylla, 256 Galasa nigrinodis, 219 Galgula partita, 223 Galium texense, 166 gall and parasitoid family, 237 gall wasp family, 237 Gamochaeta purpurea, 183 gaping panicum, 179 Gasteracantha cancriformis, 249 Gaura parviflora, 157 gecko lizard family, 204 Gekkonidae family, 204 Gentianaceae family, 155 gentian family, 155 Geococcyx californianus, 200 geometrid family, 219 Geometroidea superfamily, 219 Georgia rockrose, 170 Geotrupes sp., 240 Geotrupidae family, 240 Geraniaceae family, 155 geranium family, 155 Gerridae family, 244 Gerris sp., 244 giant lichen orb weaver, 248 giant silk moth family, 221 giant spiderwort, 154, 163, 256 giant swallowtail, 213, 214 giant walking stick, 247 Giliastrum incisum, 157 Givira theodori, 218 Glandularia bipinnatifida var. bipinnatifida, 158 Glandularia pumila, 158 glaucous-legged spur-throated grasshopper, 229 Glena quinquelinearia, 220 globeberry, 134

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gnat, 224, 239 gnatcatcher family, 202 goatsbeard, 168, 183 goatweed leafwing butterfly, 137, 138, 211, 212, 216 goldeneye phlox, 137, 153 Gomphidae family, 224, 225 Gomphocerinae subfamily, 230 Gomphus militaris, 225 goosefoot family, 163 Gossypianthus lanuginosus, 161 gourd family, 151, 163, 170, 184 graceful range grasshopper, 230 grape family, 152, 167, 189 grape leafroller, 219 grapevine beetle, 241 graphic crescent, 217 grass family, 176 grass-leaf rush, 181 grass miner moth family, 218 gray bird grasshopper, 141, 229 gray sanddragon, 225 Gray’s milkpea, 256 greater angle-wing katydid, 231 greater earless lizard, 204 greater road runner, 134, 200 great golden digger wasp, 237 great purple hairstreak, 212 great spreadwing, 228 green alga genus 193 green ash, 149, 186 green cloverworm, 222 green lacewing family, 246 green lynx, 249 green skipper, 216 green sprangletop, 178 green stink bug, 244 greenthread, 169 Grimmia laevigata, moss, 193 Grindelia squarrosa, 168, 183 ground and water beetle suborder, 239 ground beetle family, 239 ground plum, 256 Gryllacrididae family, 232 Gryllidae family, 232 Gryllus sp., 232 Guadalupe penstemon, 257 Gulf fritillary, 138, 211, 216 gum elastic, 135, 137, 150, 167, 188 gumweed, 137 Gutierrezia texana, 168

Gymnoclytia sp., 235 hackberry (emperor) butterfly, 138, 216 Haematomma sp., 132 hairy bluestem, 140 hairy-fruit chervil, 153, 161 hairy grama, 142, 176 hairy paspalum, 178 hairy stickseed, 162 hairy tridens, 177 hairy wedelia, 169 Haldeman’s shield-backed katydid, 231 half-wing, 220 Halictidae family, 236 Halloween pennant, 225 Hammaptera parinotata, 220 hammock fern, 119, 143, 174, 175, 255 handsome grasshopper, 230 hanging thief genus, 233 harlequin webworm, 219 Harmonia axyridis, 240 harvester ant genus, 245 harvestman, 248 harvestman family, 250 heart-wing sorrel, 187 Hedeoma acinoides, 156 Hedeoma drummondii, 156 Hedgehog cactus, 134, 173, 174 Helenium badium, 168, 183 Helianthemum georgianum, 170 Heller’s beardtongue, 257 Hemiargus isola, 213 Hemidacylus turcicus, 204 Hemieuxoa rudens, 223 Hemipenthes sinuosa, 233 Hemiptera order, 243 henbit, 156 Henry’s elfin, 212 Hermannia texana, 160, 188 Hesperia viridis, 216 Hetaerina americana, 227 Heteranassa mima, 222 Heteranassa moth, 222 Heterocampa astarte, 221 Heterocampa obliqua, 221 Heteronemiidae family, 247 Heteropogon contortus, 177 Heterotheca stenophylla, 169 Heterotheca subaxillaris, 169

Hexagenia sp., 242 hierba de zizotes, 161 Hippiscus ocelote, 231 Hippocastanaceae family, 149, 165, 186 Hirundinidae family, 202 Hirundo fulva, 202 Holomelina sp., 221 homomelina moth genus, 221 honey, bumble, carpenter bee family, 236 honey, bumble, stingless bee subfamily, 236 honey bee, 137, 153, 233, 236 honey bee tribe, 236 honey mesquite, 29, 130, 141, 142, 144, 148, 170, 185, 190 honeysuckle family, 148, 163 hooded windmillgrass, 137, 177 Hooker’s scratch daisy, 153, 168, 211 hop-hornbeam copperleaf, 163 Horace’s duskywing, 212 Hordeum pusillum, 178 horned bladderwort, 171 horned spanworm, 220 horse chestnut family, 149, 165, 186 horse fly family, 235 horse fly genus, 235 Houstonia pusilla, 158 hover fly genus, 234, 235 Hummbard’s small silk moth, 221 hummingbird family, 200 Hybomitra sp., 235 Hydrocotyle verticillata, 161 Hydrophyllaceae family, 156 Hylephila phyleus, 214 Hyles lineata, 221 Hylidae family, 206 Hymenopappus scabiosaeus var. corymbosus, 162 Hymenoptera order, 236, 245 Hypena scabra, 222 Hypericum drummondii, 170 Hypericum gentianoides, 170 Hypericum mutilum, 170 Ibervillea lindheimeri, 151, 170, 184 ichneumon wasp family, 237 in dex

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ichneumon wasp superfamily, 237 Ichneumonidae family, 237 Ichneumonoidea superfamily, 237 Icteridae family, 202 Icterus spurius, 202 Idaea obfusaria, 220 Inca dove, 200 Indian blanket, 159, 183 Indiangrass, 137, 178, 179 Indian mallow, 171 Indian paintbrush, 137, 160 indomitable melopotis moth, 222 Ipomoea cordatotriloba var. torreyana, 151, 155 Ipomoea lindheimeri, 151, 155 Iridaceae family, 156 Iridopsis defectaria, 220 iris family, 156 Ischnura hastata, 228 Isoetaceae family, 180, 256 Isoetes lithophila, 256 Isoetes sp., 180 isopod order, 246 Isopoda order, 246 ivy treebine. See common ivy treebine Jalysus sp., 243 Japanese brome, 177 Johnsongrass, 137, 139, 17 Juglandaceae family, 159, 186 jumping spider family, 249 Juncaceae family, 181, 256 Juncus diffusissimus, 181 Juncus marginatus, 181 Juncus torreyi, 181 Juncus validus var. fascinatus, 256 june bug (genus), 239, 241 junglegrass, 177 juniper budworm, 218 juniper hairstreak, 212 Juniperus ashei, 148, 184 juniperleaf, 162 Junonia coenia, 217 katydid family, 231 Kaulfuss’ lipfern, 134, 174, 175, 257 278

killdeer, 200 King Ranch bluestem, 137, 176 Kiowa dancer, 227 knotroot bristlegrass, 178 Krameriaceae family, 152, 159 Krameria lanceolata, 160 Kricogonia lyside, 214 Krigia occidentalis, 169, 183 Kukulcania hibernalis, 249 lacey oak, 148 Lactista azteca, 231 Lactuca ludoviciana, 169 ladder-backed woodpecker, 199, 201 ladybird beetle family, 240 Lamiaceae family, 156, 160, 165 Lamiinae subfamily, 240 Lamium amplexicaule, 156 lantana. See Texas lantana Lantana urticoides, 160, 189 Laothoe juglandis, 221 lappet, tolype, and tent caterpillar moth family, 220 lappet moth, 221 Lappula occidentalis var. cupulata, 162 large-flower buttercup, 153 large hop clover, 171 large maple spanworm, 220 large milkweed bug, 244 large orange sulphur, 215 Largidae family, 244 Largus sp., 244 lark sparrow, 201 Lasiocampidae family, 220 late boneset, 137, 153, 162 lazy daisy, 161 leaf beetle (genus), 240 leaf beetle family, 240 leafcutter bee family, 236 leafcutter bee genus, 236 leaf-footed bug (genus), 243, 244 leaf-footed bug family, 243 leaf roller moth family, 218 leatherflower. See purple leatherflower Lecanora sp., 132 Lechea san-sabeana, 256 lemon beebalm, 156 Lentibulariaceae family, 171 Lepidium virginicum, 162, 184

Lepidophora sp., 234 Leporidae family, 198 Leptochloa dubia, 178 Leptoglossus phyllopus, 244 Lerodea eufala, 213 Lespedeza stuevei, 155 Lesquerella sp., 170, 184 Lestes alacer, 228 Lestes sp., 224 Lestidae family, 228 Leucania sp., 223 Liatris punctata, 154 Libellula comanche, 225 Libellula croceipennis, 225 Libellula luctuosa, 225 Libellula pulchella, 225, 226 Libellulidae family, 225 Libytheana carinenta, 217 lichen and tiger moth family, 221 Liliaceae family, 156, 165, 180, 186, 256 lily family, 156, 165, 180, 186 Limacodidae family, 218 Limenitis archippus, 217 Limenitis arthemis, 213 Limnodea arkansana, 178 Linaceae family, 171 Lincoln’s sparrow, 201 Lindernia dubia var. anagallidea, 167 Lindheimer’s crownbeard, 255 Lindheimer’s globeberry, 151, 170, 184 Lindheimer’s morning glory, 134, 151, 153, 155 Lindheimer’s muhly, 137, 178 Lindheimer’s panicgrass, 177 Lindheimer’s prickly pear. See Texas prickly pear Lindheimer’s senna, 134, 171, 185 Lindheimer’s sida, 171 Lindheimer’s tephrosia, 256 Linum hudsonioides, 171 Litodonta hydromeli, 221 little barley, 178 little bluestem, 130, 132, 134, 140142, 178 little yellow butterfly, 215 lively mermiria grasshopper, 230 liverwort genus, liverwort, 193 lizardtail gaura, 157 Loasaceae family, 171

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loasa family, 171 Lobelia cardinalis, 159 Lobocleta ossularia, 220 Lochmaeus bilineata, 221 Lolium perenne, 178 long-horned beetle family, 239 long-horned beetle subfamily, 239, 240 long-horned cricket and katydid suborder, 231 long-jawed orb weaver family, 250 long-legged fly family, 234 long-legged fly genus, 234 lovegrass genus, 176, 177 Loxosceles reclusa, 250 Lucerne moth, 219 Lucilia sp., 234 Ludwigia peploides, 172 lunate zale moth, 222 Lupinus texensis, 155, 164, 185 Lycidae family, 240 Lycomorpha pholus, 221 Lycosidae family, 249 Lycus sp., 241 Lygaeidae family, 244 Lygodesmia texana, 154, 183 lynx spider family, 249 lyside sulphur, 141, 214 madder family, 149, 158, 166, 187 Mahonia trifoliolata, 148, 169, 183 maidenhair fern, 175 Malacosoma disstria, 221 Mallodon sp., 240 mallow family, 156, 171 Malus sp., 149, 158, 187 Malvaceae family, 156, 171 Mammillaria heyderi var. heyderi, 154, 173, 184 Manduca quinquemaculata, 221 Mangora gibberosa, 249 mangosteen family, 170 mantid and cockroach order, 242 Mantidae family, 242 many-spotted angle, 219 Marrubium vulgare, 165 Marsileaceae family, 256 mat-chaff flower, 160 Matelea reticulata, 151, 161, 182

may beetle and june bug family, 241 mayfly genus, 242 mayfly order, 242 mealy oak gall wasp, 237 Medicago minima, 170, 185 Mediterranean gecko, 204 Megachile sp., 236 Megachilidae family, 236 Meganola sp., 223 Megaphasma dentricus, 247 Megascops asio, 200 Megathymus yuccae, 213 Megisto rubricata, 213, 217 Melanoplus differentialis, 229 Melanoplus foedus, 229 Melanoplus glaucipes, 229 Melanoplus ponderosus, 229 Melanoplus sp., xvi, 137, 141 Melica nitens, 178 Melipotis indomita, 222 Melipotis jucunda, 222 Meloidae family, 241 Melolonthinae subfamily, 241 Melospiza lincolnii, 201 Melospiza melodia, 201 Menispermaceae family, 152, 165, 186 Mentzelia oligosperma, 171 Mermiria bivittata, 230 Mermiria picta, 230 Mermiria sp., 137 merry melopotis moth, 222 Mestra amymone, 214, 215 metallic wood-boring beetle, 239 metallic wood-boring beetle family, 239 Mexican buckeye, 134, 147, 150, 153, 158, 188, 211 Mexican cactus fly, 235 Mexican hat, 137, 159, 169, 183 Mexican mallow, 160, 188 Microcentrum rhombifolium, 231 Micrurus tener, 205 migratory bird locust subfamily, 229 milkweed family, 151, 161, 182 millipede genus, 247 millipede order, 247 mimic thrush family, 202 Mimidae family, 202 Mimosa aculeaticarpa var.

biuncifera, 148, 164, 185 Mimosa hystricina, 155 Mimulus glabraqtis, 172 Mimus polyglottos, 202 mint family, 156, 160, 165 Mirabilis sp., 157 Miridae family, 244 mistletoe, 190 mistletoe family, 190 mockingbird, 199 Molossidae family, 198 monarch, 123, 138, 141, 211, 216 Monarda citriodora, 156 monkeyflower, 130, 137 Montezuma, 230 moonseed family, 152, 165, 186 Moraceae family, 149, 165, 186 morning glory family, 151, 155, 163 Morus rubra, 149, 165, 186 mosquito, 224, 239 mottled euchlaena, 220 mourning cloak, 217 Mozena sp., 244 mud dauber wasp genus, 236, 237 Muhlenbergia lindheimeri, 178 Muhlenberg’s sedge, 180 mulberry family, 149, 165, 186 multicolored Asian lady, 240 musk thistle, 153 mustang grape, 137, 151, 152, 168, 189 mustard family, 154, 162, 169, 183 Mutillidae family, 245 Myiarchus cinerascens, 203 Myrmeleon sp., 246 Myrmeleontidae family, 246 Nama hispidum, 156 Narceus sp., 247 Narnia femorata, 244 narrowleaf dayflower, 154 narrow-leaf gold aster, 169 narrow-leaf yucca, 153 narrow-winged damselfly, 227 Nassella leucotricha, 178 Nasturtium officinale, 162 Nathalis iole, 214 needle grama, 137, 176 Nematocampa resistaria, 220 Nemophila phacelioides, 156 index

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Nemoria bistriaria, 220 Nemoria zygotaria, 220 Neodsplocampta sp., 233 neon skimmer, 225 Neoscona crucifera, 249 Nerodia erythrogaster, 205 netleaf clematis, 134 netleaf hackberry, 134, 150, 189 nettle family, 167 net-vein milkvine, 134, 151, 161, 182 net-winged beetle family, 240 net-winged beetle genus, 241 Neuroptera order, 246 nine-banded armadillo, 197 nipple cactus, 140, 154, 173, 184 nits-and-lice, 134, 153, 170 Noctuidae family, 221 Nolina lindheimeriana, 255 Nolina texana, 165, 180 Nomophila nearctica, 219 northern cardinal, 199, 201 northern green-striped grasshopper, 231 northern mockingbird, 202 northern paper wasp, 238 Nothoscordum bivalve, 165 Notodontidae family, 221 nursery web spider, 249 nut grass, 181 Nuttallanthus texanus, 158 nut-weevil genus, 240 Nyctaginaceae family, 156 Nymphalis antiopa, 213, 217 oakwoods ponysfoot, 151, 256 oblique heterocampa, 221 obscure grasshopper, 141, 230 obscure sphinx, 221 obtuse yellow moth, 223 Ocyptamus fascipennis, 235 Ocyptamus fuscipennis, 235 Odocoileus virginianus, 197 Odonata order, 224 Odontomyia sp., 234 Oecanthus, 232 Oedipodinae subfamily, 230 Oenothera laciniara, 172 old plainsman, 162 Oleaceae family, 149, 172, 186 Oligonicella scudderi, 242 olive family, 149, 172, 186

Onagraceae family, 157, 172 Oncopeltus fasciatus, 244 one-flower flat sedge, 181 one-seed croton, 164, 185 Opatrinae subfamily, 241 Opeia obscura, 230 Ophioglossaceae family, 256 Ophioglossum crotalophoroides, 256 Opuntia engelmannii var. lindheimeri, 159, 170, 173, 184 Opuntia macrorhiza, 170, 184 orangegrass, 134, 153, 170 orange skipperling, 214 orange sulphur, 211, 214, 215 orb weaver, 249 orb weaver spider family, 248 orchard oriole, 202 Orchelimum bullatum, 231 Orphulella sp., 141 Orphulella speciosa, 230 Orthemis ferruginea, 226 ovate-leaf cliff brake, 175 owlet moth family, 221 owl family, 200 owlfly, 246 ownfly family, 246 Oxalidaceae family, 157, 172 Oxalis dillenii, 172 Oxalis drummondii, 157 Oxyopidae family, 249 Ozark grass, 178 Pachydiplax longipennis, 226 painted bunting, 199, 201 painted lady, 138, 217 Palafoxia callosa, 154 Paleacrita vernata, 220 pale-faced clubskimmer, 225 pale-seed plantain, 165 pallid-winged grasshopper, 231 panicum genus, 176 Panicum virgatum, 178 Panopoda cameicosta, 222 Papaveraceae family, 165 paper wasp, 237, 238 paper wasp superfamily, 237 Papilio cresphontes, 213, 214 Papilio polyxenes, 213 Parachma moth, 219 Parachma ochracealis, 219 Paridae family, 202

Parietaria pensylvanica, 167 Parthenocissus heptaphylla, 257 Parthenocissus quinquefolia, 152, 189 Parus atricristatus, 202 paspalum genus, 137 Paspalum publiflorum, 178 Paspalum setaceum, 178 Paspalum urvillei, 178 Passeriformes order, 201 Passerina ciris, 201 Passiflora affinis, 152, 172, 186 Passifloraceae family, 152, 172, 186 passionflower family, 152, 172, 186 pasture grasshopper, 230 peach, 149, 158, 187 peach bush, 257 pea family, 148, 152, 154, 159, 164, 170, 185 pecan, 130, 137, 147, 149, 186 Pediodectes haldemani, 231 Pediodectes stevensoni, 231 Pediomelum rhombifolium, 159 Pelidnota punctata, 241 Pellaea ovata, 175 Pellaea wrightiana, 175 pencil, 130, 132, 134, 140, 142, 170, 173, 205 Pennsylvania Pellitory, 167 Penstemon guadalupensis, 257 Penstemon triflorus ssp. triflorus, 257 Pentatomidae family, 244 Pepsis sp., 237 perennial ryegrass, 178 pero genus, 220 Pero sp., 220 Persian speedwell, 158 Petrophilia jaliscalis, 219 Peucetia viridans, 249 Phacelia congesta, 156 Phalangidae family, 250 Phalaris caroliniana, 178 phaon crescent, 217 Phasiinae subfamily, 235 Phasmatodea superorder, 247 Phidippus audax, 250 Phigalia titea, 220 Phlox drummondii var. mcallisteri, 157

280 i n de x

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phlox family, 157 Phlox pilosa ssp. latisepala, 256 Phlox roemeriana, 257 Phoberia atomaris, 222 Phoebis agarithe, 215 Phoradendron tomentosum, 190 Phosphila miselioides, 223 Phrynosomatidae family, 204 Phthiriinae subfamiily, 234 Phyciodes graphica, 217 Phyciodes phaon, 217 Phyla nodiflora, 167 Phyllodesma americana, 221 Phyllogomphoides stigmatus, 225 Phyllophaga sp., 241 Physalis cinerascens var. cinerascens, 172, 188 Physoconops sp., 234 Phytolacca americana, 165, 187 Phytolaccaceaea family, 165, 187 Picidae family, 201 Piciformes order, 201 Picoides scalaris, 201 pigeon and dove family, 200 pillbug, 246 pill bug family, 246 Pilularia americana, 256 Pinaropappus roseus, 162 pin clover, 156 pine barren sedge, 181 pine siskin, 202 pink family, 163, 184 pink-globe prairie clover, 256 pink streak moth, 223 pink vervain, 153, 158 pipevine swallowtail, 211, 212 Pipilo erythropthalmus, 201 Piranga rubra, 201 Pisauridae family, 249 pitseed goosefoot, 163 pit vipers and vipers family, 205 plains-bellied water snake, 205 plains bristlegrass, 178 plains prickly pear, 134, 140, 142, 153, 170, 173, 174, 184 plains yellow-winged grasshopper, 230, 231 Plantaginaceae family, 165 Plantago virginica, 165 Plantago wrightiana, 166 plantain family, 165 plant bug, 244

plant bug family, 244 plateau live oak, 129, 130, 132-134, 137, 140, 142, 147, 148, 153, 171, 185, 190, 211, 233, 256 plateau spreadwing, 228 Plathemis lydia, 226 plover family, 200 plume moth family, 219 Poaceae family, 176, 256 Poecilognathus sp., 234 Pogonomymex sp., 245 poison ivy, 134, 135, 147, 151, 182 pokeweed family, 165, 187 Polanisia dodecandra ssp. trachysperma, 162 Polemoniaceae family, 157, 256 Polioptila caerulea, 202 Polioptilidae family, 202 Polistes annularis, 237 Polistes carolina, 237, 238 Polistes exclamans, 238 Polistes fuscatus, 238 Polistes metricus, 238 Polistes sp., 238 Polistinae subfamily, 237 Polygonaceae family, 166, 187, 257 Polygonia interrogationis, 213, 217 Polygonum punctatum, 166 Polypogon monspeliensis, 178 Polypremum procumbens, 162 Polytrichaceae family, 193 Pompilidae family, 237 ponderous spur-throated grasshopper, 229 Pontia protodice, 215 poor-joe, 153, 158 poppy family, 165 Populus deltoides, 149, 188 porcupine, 197 Portulacaceae family, 157, 172, 187 Portulaca pilosa, 157, 187 Portulaca umbraticola, 172 post oak, 129, 134, 135, 140, 142, 143, 147, 148, 149, 153, 186 potato family, 158, 167, 172, 188 potter wasp family, 237 potter wasp subfamily, 237 powdered dancer, 227 prairie bluet, 158 prairie buttonweed, 166 prairie flameleaf sumac, 94, 134,

147, 161, 182 prairie rain lily, 132, 134, 153, 165, 186 prairie spiderwort, 154, 163 praying mantis, 239 praying mantis family, 242 predacious diving beetle family, 239 prickly sow thistle, 169 primrose family, 166, 187 Primulaceae family, 166, 187 Prioninae subfamily, 240 Prochoerodes transversata, 220 Procyonidae family, 198 Procyon lotor, 198 Progomphus borealis, 225 Progomphus obscurus, 225 Promachus bastardii, 233 prominent and datanas moth family, 221 Prosopis glandulosa, 148, 170, 185 prostrate lawnflower, 168 Prunus persica, 149, 158, 187 Prunus texana, 257 Pseudognaphalium canescens, 169, 183 Psoloessa texana, 230 Ptelea trifoliata, 149, 166 Pteridaceae family, 175, 257 Pterophoridae family, 219 purple cudweed, 183 purple leatherflower, 151, 152, 153, 157, 187 purpletop, 137, 179 purslane family, 157, 172, 187 Pyralidae family, 219 pyralid family, 219 Pyrausta tyralis, 219 Pyrgus communis, 215, 217 Pyrisitia lisa, 215 Pyrota insulata, 241 Pyrrhopappus pauciflorus, 169, 183 queen butterfly, 138, 211, 216 Quercus fusiformis, 148, 171, 185 Quercus laceyi, 148 Quercus marilandica, 148, 171, 185 Quercus stellata, 148, 171, 186 question mark butterfly, 138, 141, 211, 217 index

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quillwort family, 180 quillwort genus, xviii, 87, 130, 132, 176, 179, 180 rabbit family, 198 Rabinosa sp., 249 raccoon, 137, 197, 198 raccoon and ringtail family, 198 Rana berlandieri, 207 Ranidae family, 207 Ranunculaceae family, 152, 157, 166, 172, 187, 257 Ranunculus macranthus, 172 Ranunculus pusillus, 166 Rasahus sp., 245 raspy cricket family, 232 ratany family, 152, 159 Ratibida columnifera, 159, 169, 183 rattlesnake weed, 182 Reakirt’s blue (butterfly), 141, 213 red admiral, 137, 138, 141, 211, 217 red fox wasp, 134, 197 red-fringed emerald moth, 220 red lovegrass, 177 red mulberry, 134, 137, 149, 165, 186 red saddlebags, 224, 226 red satyr, 213, 217 red-spotted purple (butterfly), 213 red-tailed hawk, 200 red-tailed pennant, 225 Reduviidae family, 244 red wasp, 237, 238 rescuegrass, 177 Rhus lanceolata, 147, 161, 182 Rhus virens, 147 Rhynchosia senna var. texana, 152, 171 Riccia sp., liverwort, 193 Richardia tricocca, 166 Riddel’s spike moss, 132, 134, 190 ridgeback sand grasshopper, 231 Rio Grande leopard, 137, 139, 206 rippled wave moth, 220 roach family, 242 road runner. See greater road runner robber fly family, 233 robber fly genus, 233 rock coreopsis, 132, 134, 142, 153,

168, 183 rock quillwort, 131, 256 rockrose family, 170 rock squirrel, 134, 144, 197, 198 rock wren, 202 Rocky Mountain bullrush, 181 Roosevelt weed, 137, 153, 162, 182 Rosaceae family, 149, 152, 157, 166, 187, 257 roseate skimmer, 224, 226 rose family, 149, 152, 157, 166, 187 rough cocklebur, 139 rough nama, 137, 153, 156 rough phlox, 256 round-head rush, 256 round-leaf monkeyflower, 172 round-leaf scurfpea, 159 Rubiaceae family, 149, 158, 166, 187 Rubus trivalis, 152, 166, 187 Rudbeckia hirta, 169 rue family, 149, 166, 187 Ruellia drummondiana, 255 rufous-crowned sparrow, 201 rufous-sided towhee, 201 Rumex hastahulus, 187 rush family, 181 rusty blackhaw, 148, 153, 163 Rutaceae family, 149, 187 Rutelinae subfamily, 241 Sabatia campestris, 155 sacahuista, 153, 165, 176, 179, 180 sachem, 138, 214 sad underwing, 223 Salicaceae family, 149, 167, 188 Salix nigra, 150, 167, 188 Salpinctes obsoletus, 202 salt cedar, 150, 158 Salticidae family, 249 Salvia coccinea, 160 Samea baccatalis, 219 Samolus valerandi ssp. parviflorus, 166, 187 sand dropseed, 179 sand wasp genus, 236 sandyseed clammyweed, 162 San Saba pinweed, 256 Sapindaceae family, 158, 188 sapodilla family, 150, 167, 188 Sapotaceae family, 167, 188 Sarcophaga sp., 234

Sarcophagidae family, 234 Saturniidae family, 221 Satyrium favonius, 213 savanna sparrow, 201 saw greenbrier, 134, 137, 140, 152, 188 Sayornis phoebe, 203 Say’s grasshopper, 231 Scarabaeidae, 241 scarab beetle family, 241 scarlet-leaf skullcap, 139 scarlet leatherflower, 257 scarlet spiderling, 157 Sceliphron caementarium, 237 Sceloporus olivaceus, 204 Sceloporus poinsettii, 204 Schinia citrinellus, 223 Schinia hulstia, 223 Schistocerca americana, 229 Schistocerca lineata, 229 Schistocerca nitens, 229 Schistocerca sp., 137 Schizachyrium scoparium, 178 Schoenoplectus saximontanus, 181 Sciurudae family, 198 Sciurus niger, 198 scorpion, 248 scratch daisy, 134 Scrophulariaceae family, 158, 160, 167, 172, 257 Scudderia furcata, 232 Scudderia sp., 232 Scudderia texensis, 232 Scutellaria drummondii, 156 Scutellaria ovata, 156 Scytodidae family, 250 secondary screwworm, 234 Sedum nuttallianum, 170 Selaginella arenicola ssp. Riddellii, 190 Selaginella wrightii, 190 Senecio ampullaceus, 169, 183 Senna lindheimeriana, 171, 185 sensitive briar. See bristly sensitive briar Setaria leucopila, 178 Setaria parviflora, 178 Setaria scheelei, 178 seven-leaf creeper, 257 shaggy portulaca, 157, 187 sheathed flat sedge, 181

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shepherd’s purse, 153, 162, 184, 211 shining leaf chafer subfamily, 241 short-horned grasshopper and cricket suborder, 229 short-horned grasshopper family, 229 shrubby boneset, 134, 147, 153, 162, 211 Sicariidae family, 250 Sida abutifolia, 171 Sida lindheimeri, 171 sideoats grama, 137, 140, 142, 176 Sideroxylon lanuginosum, 150, 167, 188 Sigela basipunctaria, 222 Silene antirrhina, 184 silky evolvulus, 151, 153, 163 silver bluestem, 137, 140, 141, 142, 176 silverleaf nightshade, 137, 142, 158, 188 Sisyrinchium chilense, 156 sitckleaf, 171 skimmer dragonfly family, 225 slant-faced grasshopper family, 230 sleepy catchfly, 184 sleepy sulphur, 211, 214 slender bladderpod, 255 slender bristle thistle, 153 slender copperleaf, 164 slender dwarf morning glory, 151, 155 slender hedeoma, 156, 161 slender snakecotton, 134, 153, 161 slickseed fuzzy bean, 152, 155 slim-pod rush, 181 slim-pod Venus looking-glass, 151, 154 slug caterpillar moth family, 218 small-flower milk vetch, 152, 153, 155, 185 small-flower vetch, 152, 155 smallhead sedge, 180 smallhead pipewort, 257 small palafoxia, 154 small rock lettuce, 162 small Venus looking-glass, 151, 154 Smilacaceae family, 152, 188

Smilax bona-nox, 152, 188 smooth water primrose, 139, 172 snout and bark beetle family, 240 snow-on-the-mountain, 137, 153, 164, 185, 211 soapberry family, 150, 158, 188 Solanaceae family, 158, 167, 172, 188 Solanum dimidiatum, 158, 188 Solanum elaeagnifolium, 158, 188 Solanum ptychanthum, 167, 188 Solanum rostratum, 172, 188 Solanum triquetrum, 167, 188 soldier fly family, 234 soldier fly genus, 234 Solenopsis invicta, 245 Sonchus asper, 169 song sparrow, 201 Sorghastrum nutans, 178, 179 Sorghum halepense, 179 southern crabgrass, 177 southern dewberry, 137, 152, 166, 187 southern dogface, 211, 215 southern house, 249 southwestern bristlegrass, 178 Spanish grape, 152 Sparganothis pettitana, 218 Sparganothis sp., 218 sparrow family, 201 speckled rangeland grasshopper, 230 Spharagemon cristatum, 231 Spharagemon equale, 231 Sphecidae family, 236 Sphecius speciosus, 236 Sphex ichneumoneus, 237 Sphingidae family, 221 sphinx, clearwing, and hawk moth family, 221 Sphyrapicus varius, 201 spider order, 248 spider wasp family, 237 spider wasp genus, 237 spiderwort family, 154, 163 spiderwort genus, 134, 153 spiny oak slug moth, 218 Spiragyra sp., algae, 193 Spirobolidae family, 247 Spirobolida order, 247 spitting spider family, 250

spittlebug family, 243 Spizella passerina, 201 Spizella pusilla, 202 split-leaf gilia, 157 Sporobolus cryptandrus, 179 spotted bird grasshopper, 229 spotted peppergrass, 219 spotted phosphila moth, 223 spotted sigela moth, 222 spotted spurge, 155, 164 spreading hedge parsley, 161, 182 spreading sida, 171 spreadwing damselfly family, 228 spring cankerworm, 220 springwater dancer, 227 spurge family, 152, 155, 163, 184 spurge genus, 184 squirrel family, 198 star thistle, 168 Steinchisma hians, 179 Stellaria media, 163 stemless spiderwort, 256 Stenaria nigricans var. nigricans, 158 Steniolia sp., 236 Stenopoda cinerea, 245 Sterculiaceae family, 160 Stevenson’s shield-backed katydid, 231 stickleaf, 171 sticky chickweed, 163 stiff-stem flax, 153 stilt bug family, 243 stilt bug genus, 243 stilt-walker katydid, 231 stinging nettle, 167 stink bug family, 244 stink bug genus, 244 Stiriodes obtusa, 223 stonecrop family, 170 storax family, 188 Stratiomyidae family, 234 Strigidae family, 200 Strigiformes order, 200 striped bark scorpion, 251 striped sand grasshopper, 229 striped skunk, 197 Strophostyles helvola, 152, 155, 185 Strophostyles leiosperma, 155 Strymon melinus, 213 Sturnella magna, 202 Sturnella neglecta, 202 index

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Styphnolobium affine, 148 Styracaceae family, 188, 257 Styrax platanifolius, 143, 257 subterranean dart, 223 sugar hackberry, 137, 150, 167, 189 sulphur-tipped clubtail, 225 sumac family, 147, 151, 161, 182 summer tanager, 201 sunflower family, 147, 153, 159, 161, 168, 182 superb cicada, 243 swallow family, 202 swan, goose, and duck family, 200 sweat bee family, 236 sweat bee genus, 236 swift setwing, 225 switchgrass, 134, 137, 139, 178 swordleaf blue-eyed grass, 156 sycamore, 130 sycamore-leaf snowbell, 257 Sylvilagus floridanus, 198 Sympetrum corruptum, 226 Symphyotrichum sp., 154, 162 Syrbula admirabilis, 230 Syrbula montezuma, 230 Syrphid fly family, 234 Syrphidae family, 234 Syrphinae subfamily, 235 Syrphini tribe, 235 Syssphinx hubbardi, 221 Tabanidae family, 235 tachinid fly family, 235 tachinid fly genus, 235 Tachinidae family, 235 Tachininae subfamily, 235 Tachypompilus sp., 237 Tadarida brasiliensis, 198 talayote, 161 Talinum parviflorum, 157 tall buckwheat, 166, 257 tall bush clover, 155 Tamaricaceae family, 158 tamarisk family, 150, 158 Tamarisk sp., 150, 158 tanglehead, 134, 177, 211 taper-leaf flat sedge, 180 Tarachidia binocular, 223 tarantula, 248 tarantula hawk genus, 233, 237

284

Taraxacum officinale, 169, 183 Tathorhynchus exsiccatus, 222 Teiidae family, 205 Telebasis salva, 228 Teloschistes sp., 192 Tenebrionidae family, 241 ten-petal anenome, 157, 166, 187 ten-petal thimbleweed, 139, 153 Tephrosia lindheimeri, 256 Tetragnathidae family, 250 Tettigoniidae family, 231 Teucrium canadense, 156 Texas bedstraw, 166 Texas bindweed, 151, 155, 163 Texas bluebonnet, 42, 137, 143, 153, 155, 164, 185 Texas broomweed, 153, 168 Texas buckeye, 137, 139, 147, 149, 153, 165, 186, 211 Texas bull nettle, 153, 164, 185 Texas bush katydid, 232 Texas coral snake, 205 Texas crescent butterfly, 216 Texas croton, 164 Texas cryptantha, 255 Texas dandelion, 169, 183 Texas flax, 171 Texas grama, 137, 177 Texas groundsel, 169, 183 Texas hickory, 129, 134, 137, 140, 149, 159, 186 Texas kidneywood, 148, 164, 185 Texas lantana, 137, 153, 160, 189 Texas meadow katydid, 231 Texas nightshade, 167, 188 Texas persimmon, 134, 135, 137, 140, 142, 148, 153, 163, 184 Texas phlox, 257 Texas prickly pear, 132, 134, 137, 140, 142, 153, 159, 170, 173, 174, 184 Texas sacahuista, 134 Texas sage, 160 Texas skeleton plant, 153, 154, 183 Texas sleepy daisy, 169 Texas snoutbean, 152, 171 Texas spiny lizard, 204 Texas spotted range grasshopper, 230 Texas spotted whiptail, 204, 205 Texas star, 134, 153, 155

Texas thistle, 137, 142, 153, 182, 183, 211 Texas toadflax, 158 Texas verbena, 142 Texas vervain, 137, 142, 158 Texas wintergrass, 132, 134, 140, 178 Thamnophis proximus proximus, 205 Thelesperma, 169 thick-headed fly, 234 thick-headed fly family, 234 thin paspalum, 178 thin-weed brookweed, 166, 187 Thomisidae family, 250 thread-waisted wasp family, 236 threeawn genus, 137, 140, 142, 176 three-banded lichen moth, 221 three-flower melic, 178 three-seed croton, 164 Thryomanes bewickii, 203 Thyanta sp., 244 Thymophylla tenuiloba var. tenuiloba, 169 Tibicen dorsata, 243 Tibicen superba, 243 tickle-tongue, 166, 187 tiger beetle genus, 239 tiger beetle subfamily, 239 Tillandsia recurvata, 190 Tinantia anomala, 154, 256 tiny bluet, 153, 158 Tipula sp., 235 titmouse and chickadee family, 202 toad family, 207 toothed spurge, 164 Torilis arvensis, 161, 182 Torrey’s rush, 181 Tortricidae family, 218 Toxicodendron radicans, 147, 151, 182 Toxomerus marginatus, 235 Tradescantia edwardsiana, 256 Tradescantia gigantea, 154, 163, 256 Tradescantia occideltalis, 154, 163 Tradescantia pedicellata, 154, 256 Tradescantia subacaulis, 256 Tragia ramosa, 152, 164

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Tragopogon dubius, 168, 183 trailing krameria, 152, 160 Tramea lacerata, 226 Tramea onusta, 226 tree cricket genus, 232 tree frog family, 206 Triatoma gerstaeckeri, 245 Tricopoda sp., 235 Tridens albescens, 179 Tridens flavus, 179 Trifolium campestre, 171 Trimerotropis pallidpennis, 231 Trimerotropis sp., xvi Triodanis biflora, 151, 154 Triodanis leptocarpa, 151, 154 Triodanis perfoliata, 151, 154 Tripogon spicatus, 179, 256 Tripsacum dactyloides, 179 Trochilidae family, 200 Trochiliformes order, 200 Troglodytidae family, 202 tropical leafwing, 216 tropic croton, 164 true bug order, 243 true cricket family, 232 true deer family, 197 true frog family, 207 tumble windmillgrass, 137, 177 turkey vulture, 134, 199, 200 twelve-spotted skimmer, 225, 226 twisted-leaf yucca, 174, 255 two-striped mermiria grasshopper, 230 Typhaceae family, 180, 188 Typha sp., 180, 189 Tyrannidae family, 203 Udea rubigalis, 219 Ulmaceae family, 167, 189 Ulmus americana, 150 Ulmus crassifolia, 150, 167, 189 Ululodes hyalina, 246 umbrella sedge, 181 Ungnadia speciosa, 150, 158, 188 Uresiphita reversalis, 219 Urola nivalis, 219 Urosaurus ornatus, 204 Urticaceae family, 167 Urtica chamaedryoides, 167 Usnea sp., 192

Utricularia cornuta, 171 Valerianaceae family, 257 Valerianella texana, 257 Vanessa atalanta, 217 Vanessa cardui, 217 Vanessa virginiensis, 217 variable dancer, 227 variegated fritillary, 138, 211, 216 variegated meadowhawk, 224, 226 Vasey grass, 132, 178 velvet ant family, 245 velvet ant genus, 245 venus looking-glass genus, 139 Verbascum thapsus, 172 Verbenaceae family, 158, 167, 189 verbena family, 150, 158, 160, 167, 189 Verbena halei, 158 Verbesina encelioides, 169 Verbesina virginica, 162 Veronica persica, 158 Verrucaria sp., 131 Vespidae family, 237 Vespoidea superfamily, 237 Vespula maculifrons, 238 viceroy, 217 Vicia ludoviciana, 152, 155, 185 Vicia minutiflora, 152, 155 Villini tribe, 233 vine leafroller tortrix, 218 violin spider family, 250 Viperidae, 205 Virburnum rufidulum, 148, 163 Virginia creeper, 94, 134, 151, 152, 189 Virginia opossum, 197 Virginia peppergrass, 162, 184 Virginia wild rye, 137, 177 Viscaceae family, 190 Vitaceae family, 152, 167, 189, 257 Vitis berlandieri, 152 Vitis mustangensis, 168, 189 Volucellini tribe, 234 Vulpia octoflora, 179 wainscot moth, 223 walking stick (superorder), 239, 247 walnut family, 159, 186

walnut sphinx, 221 warbler and sparrow family, 201 wasp family, 233, 236 wasp superfamily, 237 water strider bug, 137, 244 water strider family, 244 watercress, 162 waterleaf family, 156 wavy scaly cloakfern, 134, 175 weak buttercup, 166 Wedelia hispida, 169 wedgling moth, 223 western diamondback rattlesnake, 134, 205 western dwarf dandelion, 169, 183 western horse nettle, 137, 158, 188 western pygmy blue, 141, 212 western ragweed, 168, 182 western rain lily, 134 western ribbon, 137, 205 western tansy mustard, 170, 183 western wild lettuce, 169 western yarrow, 139, 141, 161 wheat head armyworm, 223 wheel bug, 245 whiptail lizard family, 205 white lace cactus, 134, 142, 154, 172 white-lined sphinx, 221 white prickly poppy, 153 white sagebrush, 161 white tridens, 179 white-tailed deer, 134, 137, 142, 143, 197 whorled water pennywort, 161 widow skimmer, 225 wild oat, 176 willow family, 149, 167, 188 willow flycatcher, 203 Wilman’s lovegrass, 177 winecup, 153, 156 wing-pod portulaca, 172 wireworm family, 240 wolf, 249 wolf spider family, 249 wood fern family, 175 Woodhouse’s toad, 207 woodpecker family, 201 Woodsia obtusa, 175 wood sorrel family, 157, 172

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woolly croton, 164 wooly lip fern, 88, 134, 174, 175 wren family, 202 Wright’s cliff brake, 134, 175 Wright’s cudweed, 169, 183 Wright’s plantain, 166 Wright’s spike moss, 134, 190 wrinkled grasshopper, 141, 231 Xanthisma texanum ssp. drummondii, 169 Xanthium strumarium var. canadense, 169, 183

Xanthoria sp., 132 Xylocopa virginica, 236 Xylocopinae subfamily, 236

yellow stonecrop, 129, 132, 134, 170 Yucca constricta, 160, 255

yellow-bellied sapsucker, 201 yellow-crescent blister beetle, 241 yellowjacket, hornet, potter, and paper wasp family, 237 yellow-kneed wasp, 137, 238 yellow nut sedge, 181 yellow passionflower, 134, 151

Zale edusina, 222 Zale lunata, 222 Zanthoxylum hirsutum, 149, 166, 187 Zerene cesonia, 215 zigzag cliff brake fern, 134 Zornia bracteata, 171 Zygnemataceae family, 193

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a ppendi x a

Subject Index

s ablation, 72 abrasion, 72–74 Adelsverein. See Mainzer Adelsverein adiabatic cooling, 106, 111 Africa, 50, 63, 107 air instability, 106, 109, 113 air mass, 100, 103, 104, 106–109, 114 air parcel, 98, 105, 106, 111, 119 air stability, 105, 106, 109 algae, 130, 137, 190, 191 alliance (NVCS), 127 alluvial deposits, 76, 79, 130, 136–138 alluvium. See alluvial deposits Álvarez de Pineda, Alonso, 11 amphibian, 204, 206 amphibolite, 61 Angelina River, 20 angular unconformity, 47 annual plant, 129, 130 Antarctica, 63, 84 antelope, 142 Apache, 7, 13–17, 24, 26, 31, 32, 35, 253 aplite (dike). See dike aquifer, 72 arachnid, 2, 248 Arapaho, 15 archaeological sites, 8, 10, 31 Archaic Period, 8, 9, 10, 14 arctic air mass, 94, 102, 104 areolate lichen, 191 arrow. See point

Arrowsmith, John (map), xvi, 23, 31 Arroyo de los Pedernales, 17 Arroyo de San Miguel, 17 artifacts (Native American), 7, 8, 9, 10, 11 ash (tree), 142 ash (volcanic), 49, 56, 64 association (NVCS), 127 asthenosphere, 47, 49 A-tent. See tent blister Atent cave, 88 Atlantic Ocean, 103, 107 aureole, 62 Austin, Moses, 18, 253 Austin, Stephen F., 18, 19, 31, 253 Austin, Texas, 15, 24, 44, 50, 69, 107, 112, 115, 117 Austin phase, 9 Azores high, 107 Backside Creek, 259 Backside Trail, 259 Baja Peninsula, 100, 113 Balcones Canyonlands subregion (natural region), 39, 125 Balcones Escarpment, 24, 39, 42, 43, 53, 69, 113, 118, 143, 255, 256 Balcones Fault Zone, 39, 42, 43, 52, 69 Balcones Igneous Province, 43, 69 Balconian Province (ecoregion), 128 basalt, 47, 49

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basement rock, 48, 63, 67 bass, 208 basswood, 142 bat, 197 batholith, 35, 48, 53, 56, 58, 62, 63, 65, 66, 77, 80, 82, 90 Battle of San Jacinto, 28 Battleship Texas State Historic Site, 1 bear, 142 Bear Mountain, 27 bedrock metate (or mortar), 9–11 bee, 132, 153 Bell County, 8 Bermuda high, 104, 107, 112 berries, 182 Big Bend National Park, 1, 43 Big Branch gneiss, 66 biotic provinces. See ecoregions biotite (mica), 56, 57, 59, 61, 67, 74, 75, 85, 90 birch, 142 bird, 2, 123, 134, 137, 141, 143, 199, 211 bismuth, 32 bison, 8, 9, 11, 13, 15, 142 Blair, Frank, 128 Blanco County, 26, 256 Blanco River, 17 blue norther, 102 blue topaz, 32 bluestem grassland, 130 Boos-Waldeck, Count Joseph de, 22

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Borden, Gail, 32 Bornhardt inselbergs, 83 Boundary Rocks, 84, 101, 259 Bourgeois-Ducos Tract, 22 braided stream, 78, 79, 136 Brazil, 56, 58 Brazos River, 18 Brown, Capt. Henry S., 18, 253 Browne, N. P. P., 28 Buffalo Hump, 25, 31 Bullhead Mountain, 28, 53 Bulverde point, 8 burned (rock) midden, 6, 9, 10, 13 Burnet, David G., 19 Burnet County, 256, 257 butterfly, 2, 132, 137, 138, 141, 143, 153, 211, 218 Butterwick, Mary, 130, 131 Buzzard’s Roost, 83 Buzzard’s Roost Trail, 259 Cabeza de Vaca, Álvar Núñez, 11, 253 cactus, 93, 97, 140, 173 Caddo, 14, 15, 20 calcium carbonate, 45 California, 26, 35, 49, 82, 253 Cambrian Period, 45, 46, 53, 55, 68, 69, 77, 78, 80, 85 campground (Enchanted Rock), 73, 79, 199, 218 camping, 6, 100, 101, 103, 197 Campside Creek, 73, 115, 116, 139, 259 Canada, 63, 85, 105 Cap Mountain limestone, 46 cap. See capping inversion capping inversion, 111, 112 carbonation. See dissolution carbonic acid, 75 Castell, Count Carl von, 22 castle koppe. See castle tor castle tor, 80, 84, 90, 135 caterpillar, 211 Cava del San José del Alcazar, 17 cave-in, x cavern (cave), 10, 17 Cenozoic Era, 41, 43 Central Texas, 7, 10, 12, 13, 15, 17, 21, 26, 27, 35, 39, 42, 44, 45, 50, 51, 55, 65, 68, 72, 83, 87, 93, 288

98, 103–105, 107, 108, 110–113, 117–119, 123, 142, 197, 199, 211, 253–257 Central Texas Climbing Committee, 30 Central Texas Mineral Region, 27, 51, 53 Central Texas Section, 125 Cerro del Almagre, 17, 31 Cerro de Santiago, 17, 253 channel, 89, 90, 96, 133, 134 chemical weathering, 71, 74, 75, 86, 90 Cherokee, 15, 20 Cheyenne, 15 Chihuahuan Desert, 1, 95, 103, 123 Choctaw, 20 Cibolo, 12 cicada, 141, 206, 243 Civil War, 26, 254 class (NVCS), 127 clay, 66, 67, 74, 75, 130, 139, 141 Clear Fork Period, 8 climate, 8, 117, 119, 123, 125, 127, 142 climax community (seral stage), 127, 142 climbing (climbers), 1, 6, 30, 83, 85, 135 cloud (formation), 106 Clovis, 8 Coal Creek Domain, 65–68 Coal Creek Plutonic Complex, 66 Coal Creek serpentine, 66 Coalhuitecan, 16 cold (cool), 8, 93, 94, 101, 103, 104, 119, 147 cold front, 94, 95, 100–103, 104, 109, 110, 112, 211 Cold Spring Granite Company, 27 colluvium, 91 colonization contract, 18–20, 23 colony. See settlers Colorado Bend State Park, 75 Colorado River. See Lower Colorado River Comanche, 7, 13–15, 17, 21, 22, 24–27, 31–35, 253, 254

Comanche Creek gneiss, 67 community. See plant community community (ecoregion), 127 Concho County, 26 condensation, 98, 106 Confederate States of America, 8 conglomerate (rock), 79 contact metamorphism, 62 continental arctic air mass, 103 continental crust. See crust continental margin island arc, 49, 64, 67 continental polar air mass, 103, 104, 108–110, 112 continental shelf, 48 continental tropical air mass, 103–105, 108, 110, 111, 114 convection current, 49 copper, 32 Coronado, Vázquez de, 11, 12 Cortés, Hernán, 11 country rock. See host rock Coushatta, 20 Crabapple, 29 craton, 62 crayfish, 208 Cretaceous Period, 43, 44, 46, 50, 52–55, 69, 77, 80 Cretaceous Seaway, 44, 45 crevice succession, 129 cricket, 229 croton, 137 crust (continental and oceanic), 47–49, 59, 63, 66, 68, 69, 77 crustose lichen, 129–131, 191, 192 crystal (crystalization), 56–61, 65, 66, 75, 77 CTCC. See Central Texas Climbing Committee Culiacán, 11 cumulus cloud, 106, 111 cyanobacterium, 191 Dallas–Fort Worth, 50 damselfly, 2, 137, 139, 143, 224 dart. See point Davis Mountains, 43 deciduous forest, 123 declaration of independence, Texas, 19 deer, 11

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deformation, 48, 49, 59, 60, 63–65, 67, 68 Del Rio, 44 deposition (deposits), 44–47, 55, 66, 71, 77–81, 98 desert, 93, 100, 103, 119, 142 desert varnish. See water staining Devils River State Natural Area, 9, 10, 69 Devonian Period, 45, 46 dew point, 98–100, 104, 106, 110, 114, 119 dew point front. See dry line D’Hanis, 117 diagenesis, 45, 69 Díaz, Melchor, 11 dike, 56, 58–60, 62, 65, 67, 68, 86, 87, 90, 134 diorite, 56, 66 disconformity, 47 dissolution, 74, 75 division (physiographic region), 124 d’Orvanne, Alexander Bourgeois (tract), 22, 23, 25, 254 doughnut, 86, 87, 90 downcutting (stream), 78, 79 dragonfly, 2, 115, 137, 139, 143, 224 drizzle, 99, 101, 102, 108 drought, 93, 96, 98, 114, 115, 117, 118, 138, 139, 147, 208 dry lapse rate, 119 dry line, 95, 99, 103, 104, 108, 110–112 Ducos, Armand, 22 Dutch Mountain, 28, 53 earthquake, 42, 69 eastern black swallowtail, 213 eastern woodlands, 93 East Texas, 18, 21, 113, 114, 256 Echo Canyon, 92, 135 Echo Canyon Creek, 135, 139 Echo Canyon Outcrop, 259 Echo Canyon Trail, 259 ecoregions, 127, 128 ecotone (ecoregion), 127 ecozone (ecoregion), 127 Edwards, Haden, 19 Edwards limestone, 72 Edwards Plateau, 1, 14, 39,

42–44, 46, 51, 53, 90, 95, 98, 110, 113, 117, 119, 123, 128, 136, 140, 142, 143, 199, 255–257 Edwards Plateau Region (ecoregion), 128 Edwards Plateau Region (natural region), 125 Edwards Plateau Section (physiographic region), 125 Ellenburger Group, 46 El Lomeria, 17 El Mocho, 17 El Niño, 93, 114 El Paso, 16 empresario. See colonization contract Enchanted Rock (SNA), 1–3, 7–11, 13, 15–18, 20–24, 26–31, 33, 34, 39, 43, 44, 53, 54, 57–59, 64, 66, 68, 71, 73, 74, 76, 78–81, 83, 84, 87, 93, 95, 96, 99, 100– 102, 104, 105, 107, 115, 117, 119, 123–125, 128, 131, 136, 138–144, 147, 174, 176, 192, 197, 204, 207, 218, 253, 254, 259 Enchanted Rock Archaeological District, 11 Enchanted Rock Batholith, 53, 56, 57, 59, 61, 62, 65, 67, 68, 76, 77, 80, 84, 90, 139 Enchanted Rock Cave, 87 Enchanted Rock Dome, xviii, 28, 38, 53, 77, 79, 83, 84, 92, 116, 129, 135, 144, 151, 199 endemic (species), 14, 123, 143, 255–257 Ensor point, 8 Eocene Epoch, 43 equilibrium (thermal), 106 Erant Reichs, 24 erosion, 1, 45, 46, 49, 52, 65, 68, 70–72, 76–80, 84, 85, 91, 98, 113 Escalante, 15 escarpment, 39, 42, 43, 53, 69, 76, 256 etched pothole. See weathering pit Eufala skipper, 213 Europe (European), 11, 13, 21, 25, 63, 254 evaporation, 96, 97, 99, 142

exfoliation dome, 35, 80, 82–84, 86, 88–90, 131, 133–135 exfoliation sheet, ix, 38, 70, 82–88, 90, 96, 131 expedition (exploration), 11, 12, 14, 16, 31, 33 extrusion, 49, 56, 59 facies (metamorphic), 61 fair weather cumulus. See cumulus cloud Fairland point, 8 fairy shrimp, 87, 97, 103, 132, 207 fall (season), 94, 95, 97–102, 104, 105, 107, 112, 138, 151, 153, 173, 211 False Dome, 259 Faltin, Albert, 28 farming, 24 fault, 41, 43, 52, 69 fault zone, 41, 43, 44 Fenneman, Nevin, 124 fern, 144, 174, 190 Ferrell cell, 104, 105, 107 fire ants, 142 first terrace (riparian zone), 136 Fischer, Heinrich Franz. See Fisher, Henry fish, 115, 137, 207, 208 Fisher, Henry, 22, 25 Fisher-Miller Tract, 22–25, 254 Flagpole, 83 flint, 10, 32 flood, 1, 79, 97, 98, 103, 113–118, 130, 136–138 flood plain, 79 Florida, 11, 253, 255 floristic characteristics, 126 flowering plants, 2, 137, 140, 142, 152, 153, 182 flow foliation, 59, 60 flyway, 123, 199, 211 FoER. See Friends of Enchanted Rock fog, 99, 100, 108 folding, 60 foliation, 60, 65, 80 foliose lichen, 129, 130, 132, 191, 192 food chain. See food web food network. See food web food web, 127 index

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forest, 1, 123 Forgotten Dome, 259 formation (geological), 46 formation (NVCS), 127 Fort Griffin, 26 Fort St. Loius, 15, 253 fracture, 80, 81, 82, 84, 90, 97, 134, 173 fracture zone. See fracture Fredericksburg, 7, 16, 21, 24–27, 29, 93, 95–98, 114, 115, 254 Fredonian Rebellion, 19, 253 freeze, 94 freeze-thaw cycle. See ice wedging freezing rain, 98, 110 French (France), 7, 11, 15–18, 20–22, 31, 35, 253 Freshman Mountain, xiv, 72, 83, 133 Freshman Mountain Creek, 139 Friends of Enchanted Rock, 30 Frio point, 8 frog, 115, 206 Frog Pond, 115, 139, 205, 206, 224 front. See cold front; warm front frontier, 7, 24, 25 Frontside Trail, 259 frost, 99 fruit, 182 fruticose lichen, 191, 192 fungi, 191 gabbro, 47, 56 Galvan, Lt. Juan, 16, 31 Galveston, 11, 24 Gault Site, 8 Geh mit ins Texas, 22 geological time scale, 40 geomorphology, 124, 125, 127 Georgia, 35, 255, 257 Germans (Germany), 1, 7, 21, 22, 24–26, 28, 35, 254 giant swallowtail, 213 Gillespie, Richard Addison, 26 Gillespie County, 2, 10, 25, 26, 28, 143, 211, 224, 254, 256, 257 glacier (glaciation), 82–84, 117, 142 glauconite, 75 global warming, 119 gnamma, 86–87, 90 290

gneiss, 61, 64, 66, 67 goat, 142 gold, 7, 31, 32 Goliad, 19 Gonzales, 19 Gorman Falls, 75 Gorman Formation, 46 Gould, Frank, 128 grade (metamorphic), 61, 62, 64, 67 gradient. See stream gradient Grand Canyon, 53 grandiorite, 57 granite, 1, 10, 27, 29, 32, 33, 47, 56–60, 67, 70–74, 76–78, 80, 81, 83–87, 89–91, 94, 96, 97, 122, 123, 130–137, 139, 140, 173, 174, 190, 191, 192, 199, 204, 205, 229, 259 granite flank (sub)zone, 133, 134, 151, 173, 190, 197, 205 Granite Mountain, 27 granite outcrop association (plant community), 128 granite perimeter (sub)zone, 134, 135 granite top (sub)zone, 131, 132, 133, 134 granite zone, 130, 131, 138 granitrillen. See channel granulite, 61 Grape Creek Pluton, 62, 67 graphite, 32 grasses, 137, 139–142, 176, 229 grasshopper, 137, 139, 229 gravel succession, 129 gray hairstreak, 213 Great Plains, 1, 7, 10, 44, 93, 105, 111, 123 Great Plains Province, 125 Great Unconformity, 44, 68, 76, 77, 84 greenschist, 61 Grenville Orogeny, 62, 63, 66, 76, 77 grind stone. See metate; mortar group (NVCS), 127 grus, 73, 75, 78, 79, 82, 84, 85, 87, 88, 97, 122, 129, 132–135, 137, 174 Guadalupe River, 17, 39, 117 Gulf air, 102, 103 Gulf Coast, 42, 43

Gulf Coastal Plain, 42 Gulf of Mexico, 1, 11, 41, 45, 51, 73, 78, 95, 99–101, 103, 107, 108, 110–114 Hadley cell, 104, 105, 107 hail, 103 Half-Dome, 35, 82 Hays, Capt. John Coffee “Jack,” 23, 34, 254 headright (certificate), 20, 24, 27 headwater advance, 78 heat, 93, 94, 98, 99, 107, 123, 153 heat index, 98–100 hematite, 75 Hickory Creek, 46 Hickory sandstone, 32, 46, 68, 76, 77 High Plains, 14, 123 high pressure, 104, 105, 107, 108, 112 Highway 965, 141 Hill Country. See Texas Hill Country Hill of Red Ochre, 31 Himalayas, 49, 50, 68 Historic Period, 8, 10 Hodges number, 144, 218 Honey Creek, 17, 27, 31 Honeycut Formation, 46 Honey Eaters, 24 hornblende, 57, 67 horst and graben terrain, 52, 53 host rock, 56, 59, 62, 68 Houston, Samuel, 19, 20, 21, 22 Houston, Texas, 100 Hueco Tanks State Historical Site, 10 humidity, 93, 98–101, 103, 107– 109, 119 hummingbird, 133, 153 hurricane. See tropical system Hurricane Katrina, 114 Hurricane Rita, 113 hydration (reaction), 74, 75, 91 hydrological system, 125 hydrolysis, 74, 75 hydrosere, 128, 130 hydrostatic pressure, 72 ice age, 8, 35, 82 ice sheet, 85

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ice wedging, 72–74, 84 igneous rock, 47, 55, 56, 62, 65, 66, 68, 69, 80, 84, 94 immigration, 1, 7, 18–20, 24, 25, 27 Inks Lake gneiss, 67 Inks Lake State Park, 67 insect, 2, 3, 143, 239 inselbergh. See Bornhardt inselbergs instability. See air instability Interior Plains Division, 125 Interstate Highway 35, 107 inundation (from the sea), 44– 46, 49, 50, 68, 77, 80, 84 invasive species, 143 iron (ore), 27, 31, 32, 75, 76 isostatic balance (adjustment), 77, 80 jet stream, 95, 103, 104, 105, 107, 115 Jicarillo, 13, 15, 24 joint. See jointing jointing, 80, 81, 83–85 Jones, Anson, 26 Jumano, 14, 16 Junction, 12 Jurassic Period, 41, 43, 44, 51 Jurassic-Triassic Uplift, 43 Kalahari protocontinent, 63, 64 kamenitza. See weathering pit Kansas, 12, 108, 115 kaolinite, 74, 76 Karankawa, 11 karst topography, 75, 87 Katemcy Pluton, 53, 68 katydid, 229 Kennedy, William, 32 K feldspar. See potassium feldspar Kickapoo, 20 killer bee, 233 Kimbel County, 26 Kingdom of Zilch, 6 Kiowa, 13, 15 koppe. See castle tor Kreische Brewery State Historic Site, 1 laccolith, 56

Lake Buchanan, 27 Lake Travis, 115, 117 Lamar, Mirabeau, 20, 21 Lampasas Cut Plain (ecoregion), 128 Lampasas Cut Plain subregion (natural region), 125 land grant, 20, 21, 27, 28 La Niña, 93, 114, 115 lapse rate, 106 Laramide Orogeny, 43, 69 La Salle, René-Robert Cavelier Sieur de, 15 late seral stage, 128 Laurentia, 50, 51, 63–68 lava, 49 LBJ School of Public Affairs, 125 lead, 32 Legion Creek Pluton, 53, 67 Lehmann Shelter, 10 Leiningen, Count Victor zu, 22 leprose lichen, 191 leucogranite, 57 leucomonzite, 57 Level III ecoregion, 128 lichen, 73, 88, 90, 91, 93, 132, 190, 191 lifting process, 106 limestone, 26, 43, 45, 52, 54, 71, 72, 75, 76, 87, 90, 98, 123, 130, 136, 144, 191 Lion Mountain sandstone, 46, 75, 76, 91 Lipan, 13, 15, 16, 17, 24, 253 lithic scatter, 10 lithification, 45 lithosphere, 47, 48 Little Rock Dome, xviii, 83, 102, 135 Little Rock Dome Spur, 259 live oak–Ashe juniper park (vegetative type), 127 live oak-mesquite-Ashe juniper park (vegetative type), 127 live oak–mesquite park (vegetative type), 126 Live Oak–Mesquite Savanna subregion (natural region), 125 liverwort, 130, 190, 193 lizard, 133, 134, 144, 204, 205 Llanite, 67, 68

Llanite Quartz Porphyry Dike, 68 Llano, 26, 27, 51, 67, 68, 94–97, 114, 115, 117, 118 Llano Basin, 51, 53, 76, 95 Llano Complex, 8 Llano County, 2, 10, 26, 28, 32, 53, 117, 143, 211, 224, 254, 256, 257 Llano Fault Zone, 52, 53 Llano front, 63, 64 Llano Region, 1, 2, 8, 9, 12, 23, 27, 32, 39, 42–44, 46, 47, 52–55, 57, 59, 62–69, 71, 72, 74–80, 84, 94, 95, 98, 107, 123, 126–128, 130, 140, 143, 144, 179, 211 Llano River, 12, 13, 16, 17, 22, 39, 43, 53, 54, 78, 79, 98, 117 Llano Uplift, 51, 53, 54, 80, 144, 255–257 Llano Uplift Region (natural region), 125 load. See stream load lobed lichen, 191, 192 Lone Grove Pluton, 53, 68 Longhorn Cavern, 75 Lookout Spur Trail, 259 Loop Trail, 259 Los Almagres, 17, 31 Los Almagres Mining Company, 27, 32 Lost Creek gneiss, 62, 67 Lost Dome, 259 Louisiana, 255, 256 Louisiana Purchase, 18, 253 lovegrass sp., 137 Lower Colorado River, 17, 22, 32, 39, 41, 53, 73, 78, 79, 91, 115, 117 low pressure, 105, 107–109, 112 Loyal Valley (granite), 27 Lungkwitxz, Karl Friedrich Hermann, 28, 29, 254 magma, 49, 53, 56–60, 63, 69 magmatic enclave, 59, 60 magnetite, 32 Mainzer Adelsverein, 22, 254 major riparian zone, 136, 138, 139 mammal, 2, 134, 143, 197 manganese, 32 mano, 9, 10, 13 mantid, 242 index

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mantle, 47, 48, 49, 66, 69 maple, 142 Marathon, 50 Marble Falls, 8, 27, 53, 57, 80, 115 Marble Falls limestone, 46 margin sheeting, 81, 89 maritime polar air mass, 103 maritime tropical air mass, 103–105, 109–114 Martínez, Anavato and María, 27, 28, 254 Mason County, 26, 61, 62, 211, 224, 254, 256, 257 Matagorda Bay, 15, 24, 78 Maverick, Samuel and Mary, 28, 254 Mayeyes, 13 McCulloch County, 26, 256 meandering (stream), 78, 79 mechanical weathering, 71, 72, 74, 75, 86, 90, 191 Medina, 117 Medina County, 117 melt zone, 63, 64 Menard County, 26 Mendoza, Antonio de, 11 Mescalero, 13, 15, 24 Mesoproterozoic Era, 62 Mesozoic Era, 41, 51 mesquite grassland association (plant community), 128, 130 mesquite grassland zone, 131, 138, 140, 141, 173, 205 metamorphic rock, 47, 55, 61, 66–69, 72, 76, 90 metamorphic sequence, 61 metamorphism, 59–64, 65–67 metate, 9, 10, 13, 14 Meusebach, Ottfried Hans von, 24–26 Mexican Congress, 19 Mexican War of Independence, 18, 253 Mexico (Mexican), 7, 11, 16, 19–22, 24–27, 35, 50, 63, 66, 103, 105, 110, 113, 119, 143, 174, 211, 253, 257 mice, 3, 197 microclimate, 119 microcline, 67, 69 midden. See burned (rock) midden

mid-level ridge, 112 mid-level trough, 95, 112, 113 mid-ocean ridge, 49, 69 Midway Sill, 62 migraton, 10, 14, 15 Miller, Brukart, 22 mimic bee, 233 Minnesota, 85, 95 minor riparian zone, 136, 139 Miocene Epoch, 42, 43, 69 Miranda y Flores, Don Bernardo de, 17, 31, 32, 253 mission, 15–17, 19 Mission San Antonio de Valero, 16, 253 Mission San Francisco de los Tejas, 16 Mission Santa Cruz de San Sabá, 16, 17, 253 Mississippian Period, 50 Mississippi River, 11, 79, 117 mixing zone, 111 Mohorovicic discontinuity, 69 molybdenum, 32 monoculture, 129 monsoonal flow, 107 monzonite, 57 Moody, Dan, 29 Mopechucope, 25 Morgan Creek limestone, 46 mortar, 9, 10 Moscovo, Luis de, 11 moss, 129, 130, 190, 193 Moss (family), 11, 26, 29, 30, 254 Moss, Aaron (A. F.), 28 Moss, Charles (C. T.), 28 Moss, Charles H., 28 Moss, John, 28 Moss, Julie, 28 Moss, Mathew, 28 Moss, Tate, 28 Moss Creek, 139, 259 Moss Lake, 115, 139, 206, 224 moth, 2, 144, 153, 211, 218 mountain lion, 142 mountain root zone, 49 mourning cloak, 213 mudstone, 45, 61 Mueller, Brukart. See Miller, Brukart muscovite (mica), 61 mushroom rock, 74, 85

Nacogdoches, 19 Narváez, Pánfilo de, 11 National Natural Landmark, 30 National Registry of Historic Places, 11, 25, 27, 254 National Vegetative Classification System, 127 National Weather Service, 114 Native Americans, 1, 7–18, 20, 21, 25–27, 31–35, 142, 254 natural region, 125 Nature Conservancy, 28, 30, 127, 254 Nearctic ecozone, 127 Neches, 20 New Braunfels, 24 New Mexico, 12, 14–16, 26, 107, 253 New Spain, 1, 7, 11, 18 newt, 204, 206 Nightingale Archaeological Site, 8 Nolan point, 8 nonconformity, 47, 68 normal fault, 41, 42, 53 North America, 8, 50, 62, 63, 103, 107, 114, 253 North American plate, 49 North Creek, 139 North Dome, 259 North Texas, 15, 26, 105, 107, 256 North Walnut Springs Creek, 115, 136, 139, 259 Nueces River, 26 NVCS. See National Vegetative Classification System oak savanna association (plant community), 128, 130 oak savanna zone, 130, 138, 139, 140 oak woodlands. See oak savanna association (plant community) Oatman Pluton, 67 occluded front, 110 ocean basin, 49, 64 oceanic crust. See crust Oklahoma, 26, 50, 115, 254, 257 Old San Antonio Road, 20 Oligocene Epoch, 41

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Omernick, Jim, 128 opferkessel. See weathering pit Ordovician Period, 45, 46, 53, 55, 77 orogen, 49 orogeny, 48, 49 orthoclase, 69 orthographic variations, 106 Ouachita Mountain (Range), 50, 69 Ouachita Orogeny (Orogen), 50–53, 77 outflow boundary, 95, 113 overrunning, 101, 110 owls, 199 oxidation, 74, 75 Pacific Ocean, 95, 100, 101, 103, 110, 113, 114 Packsaddle Domain, 66–68 Packsaddle Mountain, 26, 28, 31 Packsaddle schist, 62, 65, 67, 74, 76, 130, 133, 139, 141 Padilla, Lt. Juan, 18 Paleocene Epoch, 41 Paleo-Indian Period, 8, 35 Paleozoic Era, 50 Paleozoic Mountain Building Era, 50 Pangaea, 43, 50, 69 panhole. See weathering pit parcel. See air parcel Parilla, Col. Diego Ortiz, 17 Pecos River, 9, 39, 95, 117 Pedernales (point), 8 Pedernales River, 10, 16, 17, 24, 32, 39, 98, 117 Pedernales State Park, 98 pedestal rock. See mushroom rock pegmatite. See dike Penateka, 15, 24 Pennsylvanian Period, 45, 46, 53, 55, 77 perennial plant, 129 periodite, 66 permability, 71–73, 75 petroglyph, 9 Phanerozoic Eon, 41, 69 phenocryst, 57 phenocryst alignment. See flow foliation

physiognomic characteristics, 126 physiographic region, 124 Pinto Trail, 16 pioneer species (community), 87, 127, 129 pipe, 56 Pirate Rocks, 70 plagioclase feldspar, 56, 57, 74, 75, 85, 90 Plainview point, 8 plant association, 130 plant community, 76, 127, 128, 130, 139 plant subzone, 131 plant succession, 87, 129 plant zone, 130, 131, 173 plate, 48, 49, 62, 63 plate boundary, 49 plate tectonics, 47–49, 77 platinum, 32 platy parallelism. See flow foliation pluton, 56, 62–64, 67, 68 plutonic igneous rock. See igneous rock pod, 182 point, 8–11, 13 Point Peak siltstone, 46 polar cell, 104, 105, 107 polar jet stream, 104, 105 Polk, James, 26 pore (space), 71–73, 75 porosity, 71 porphyritic, 57, 68 post oak (savanna) plant community, 76 post-Toyah phase, 9 potassium feldspar, 32, 56–60, 69, 73, 76, 85, 90 pottery, 8, 10 Pre-Archaic Period, 8 Precambrian, 63, 66, 69 precipitation, 93, 95, 96, 102–105, 107, 114, 117–119, 142 Prehistoric Period, 8–10, 35 presidio, 15–17 Presidio San Antonio de Béjar, 16, 253 Presidio San Luis de las Amarillas, 17, 253 prickly pear, 130, 142

primary succession (seral stage), 127 private park, 10 Proterozoic Eon, 62 province (physiographic region), 124 pygmyweed, 130 Quapaw, 20 quartz, 31, 56–59, 66, 67, 73–75, 79, 85, 90 Quivira, 7, 12 Radiant Red (granite), 27 radioactive decay, 57 radioactive element, 32, 57 rain (rainfall), 92, 93, 95–98, 100–102, 108–110, 112–118, 122, 132, 136–139, 153, 173, 206, 211 rain band, 113 Red Mountain gneiss, 67 Red River, 17 region, 123 region (natural region), 125 region (physiographic region), 124 regional metamorphism, 62, 64 regolith, 76, 87, 97 Reid, Samuel J., 33, 34 relative humidity, 98, 99 reptile, 143, 144, 204 Republic of Texas, 1, 7, 8, 19–23, 25–27, 253 reverse fault, 42 rhyolite (dike), 59, 64, 65, 68 ridge (high pressure), 104, 107, 112 rifting, 49, 50, 65, 67 rift valley, 49 Riley Formation, 46 Riley Mountains, 31, 52, 53 rill. See channel rimrose lichen, 191 Rio Colorado, 17 Rio del Alarcon, 17 Rio de las Chanas, 13, 17 Rio de los Llanes, 13 Rio del Plata Craton, 63, 64 Rio del San Antonio de Ahumada, 17 Rio del San Miguel, 17 index

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Rio del San Xavier, 16 Rio Grande River, 9, 16, 20, 26, 69, 112, 117 Rio Grande Valley, 101 riparian association (plant community), 127, 128, 130 riparian zone, 130, 135, 144 Robinson, James, 28 Rock Clarke Wall, 72 rock pool succession, 130 rock shelter, 9 rock surface succession, 129 Rocky Mountains, 41, 43, 103, 110 Rodinia, 62, 63, 67, 68, 77 root zone (mountain), 77 Round Rock Period, 8 rush, 137, 176, 180 Sabine River, 20 saddlebag (dragonfly), 224 salamander, 204, 206 San Andreas Fault, 49 San Antonio, 12, 15–17, 19, 22, 43 sandstone, 43, 45, 46, 68, 72, 75–77, 79, 144 Sandy Creek, 10, 17, 30, 32, 33, 43, 53, 67, 73, 76, 78, 79, 96, 98, 115, 116, 136, 138, 139, 141, 151, 193, 199, 204, 205, 207, 208, 224 San Felipe de Austin, 18 San Gabriel River, 16 San José Mission, 33 San Marcos Period, 8 San Marcos River, 17, 39 San Saba, 18, 27 San Saba County, 26 San Saba dolomite, 46 San Saba–Ellenburger Aquifer, 72 San Saba mine, 17, 30 San Sabá mission, 17, 31 San Sabá presidio, 17 San Saba River, 25, 79 Santa Anna (Indian Chief), 25 Santa Anna, Antonio López y, 19, 20, 253 saturation, 98, 99 saw greenbrier, 151 schist, 61, 62 Schleicher County, 26 schlieren, 59, 61, 69, 88, 90

Scottsbluff point, 8 secondary succession (seral stage), 127 section (physiographic region), 124 sedge, 130, 137, 139, 176, 180 sediment, 45, 46, 50, 64, 78, 91 sedimentary rock, 44, 45, 48, 53, 55, 60, 66 sedum, 103, 129 seismic activity, 44 Seminole Canyon, 9, 10 seral stage, 127, 128 serpentine, 32, 66 settlers (settlement), 18, 19, 20, 25–27 Seven Cities of Gold, 11 shale, 46 Shawnee, 15, 20 sheep, 142 sheeting, 81 sherd, 10, 11 Sherman’s Regiment, 28 shrub, 133, 134, 139, 147, 151, 239 sill, 56, 67 siltstone, 45 Silurian Period, 45, 46 silver (mine), 1, 7, 17, 18, 23, 27, 28, 31, 32 sinkhole, 75 site. See archaeological sites skink, 204, 206 skunk, 197 slab, 82–84, 88 Slator, Damon J. D., 28 slave (slavery), 19, 26, 253 sleet, 98, 102, 110 Smith, Henry, 19 Smithwick shale, 46 snail, 208 snake, 204, 205 snow(fall), 92, 98, 102, 108, 117 soapstone, 32 Society of Nobelmen. See Mainzer Adelsverein soil, 2, 24, 76, 87, 90, 98, 127, 129, 130, 132, 136, 137, 140, 174 Solms-Braunfels, Prince Karl Frederich Wilhelm Ludwig, 22, 24, 25, 254 solution pan. See weathering pit Soto, Hernando de, 12, 253

source rock, 53 South America, 8, 50, 51, 63, 114 South American Boulders, xiv, 133 Southern Continent, 63–66, 68, 69 southern hairstreak, 213 southern oscillation, 114 South Texas, 10, 255, 256 Spanish (Spaniards and Spain), 7, 8, 10–19, 24, 27, 35, 253 Speiss, Hermann, 25 Spencer collection, 11 Spencer site, 10 spheroidal weathering, 73, 74, 83 Spicewood, 51 spike moss, 129, 130, 174, 190 Split Rock, 6 spring (season), 20, 94, 97, 98, 103–105, 107, 108, 112, 115, 123, 133, 153, 173, 199, 211, 218, 224, 239 spring (water), 32, 97, 98, 115, 208 squall line, 109 squamulose lichen, 191, 192 stationary front, 110 Stephen F. Austin colony, 28 stock, 56 Stockton Plateau, 128 straight-line winds, 113 stratigraphic column, 46 stratum, 45–47 stratus cloud, 110 streambed, 79, 91, 136, 137 stream gradient, 78–80 stream load, 79 stream terrace, 78–80, 130, 136 subclass (NVCS), 127 subduction (zone), 48, 49, 53, 63–65 subregion (natural region), 125 subsidence, 49, 79 subtropical jet stream, 101, 103–105, 112 subtropics, 1, 93, 100, 107, 119, 123, 211 subzone (plant). See plant subzone succession. See plant succession succulent, 97 summer, 20, 93, 97, 99, 100, 103–105, 107, 110, 112, 114, 115,

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117, 138, 153, 199, 211, 218, 224, 229 summer pattern, 103, 107 Summit Trail, 34 Sundance Sea, 43, 45, 51 Sunset Red (granite), 26 sunshine, 95, 106, 112 supercell, 112 surface high. See high pressure surface low. See low pressure Sutton County, 26 syntectonic, 62, 67, 68 system (NVCS), 127 tadpole, 137, 206 tafonic undercutting. See margin sheeting talc, 32 Tanyard Formation, 46 Taovaya, 17 Taysha, 12 tectonics. See plate tectonics Tehuacana, 15 temperature, 8, 93–95, 97–103, 105, 106, 107–111, 114, 115 tent blister, 88, 89 terrace (stream). See stream terrace terrane, 49, 63 Tertiary Period, 41 Texan(s), 7, 18, 19, 24 Texas, 1, 3, 7–16, 18–22, 24, 28–30, 32, 34, 63, 64, 69, 72, 76–78, 83, 95, 96, 100, 104, 105, 107, 110, 111, 113, 115, 117, 125, 128, 143, 254, 256 Texas, 32 Texas (Gulf) coast, 11, 26, 93, 95, 107, 110, 143, 253 Texas Hill Country, 1, 17, 39, 43, 69, 75, 76, 91, 117, 130, 142, 144, 174 Texas Panhandle, 12, 15, 112 Texas Parks and Wildlife, 30, 126 Texas Pink (granite), 26 Texas Provisional Government, 19 Texas Rangers, 24, 26, 33 Texas Red (granite), 27 Texas State Capitol, 26, 80 Texas Valley Country, 41 thalloid tissue, 91, 191

Thrall, 117 thunderstorm, 97, 100, 102, 103, 107, 109, 112–114 tin, 32 tinajitas. See weathering pit TMC. See Town Mountain Granite Complex toad, 115, 206 Tohaha, 13 Toho, 13 Tom Green County, 26 Tonkawa, 7, 13–16, 24, 26, 32, 33, 35, 253 topaz. See blue topaz tor. See castle tor tornado, 111, 113 Town Mountain granite, 57, 58, 81 Town Mountain Granite Complex, 57 Toyah phase, 9, 10 trade, 10, 13, 19, 31 trade winds, 114 transition area (riparian zone), 136 Trans-Pecos Igneous Province, 43 transportation, 73, 76, 78, 79, 134 travertine, 75 Travis County, 28 Treaty of Guadalupe Hidalgo, 26 tree, 115, 133–135, 137, 139, 140, 142, 144, 147, 151, 191, 239 Triassic Period, 44, 51 trilobite, 46, 91 Tropical Storm Amelia, 117 Tropical Storm Erin, 115 tropical system, 24, 95, 100, 101, 112–114, 119 trough (low pressure), 95, 105, 112 tungsten, 32 Turkey Peak, 81, 84 Turkey Peak Trail, 259 turtle, 115, 139, 204, 206 Twin Cities, 95 Twin Sisters Period, 8 unconformity, 46, 47 United States, 8, 14, 18, 19, 21, 22, 25, 26, 35, 88, 103, 108, 110, 112, 114, 123, 124, 253

unroofing, 65, 67, 80, 81 unstable air. See air instability uplift, 45, 79, 80 upper air disturbance, 95, 100, 103, 105, 112, 113, 115 uranium, 1, 32, 57 Valley Spring domain, 61, 65–67, 76 Valley Spring gneiss, 32, 62, 67 vegetative types, 126 Verein zum Schutz deutcher Einwanderer im Texas, 22–25, 31 vermiculite, 32, 75, 76 vernal pool, 86–87, 96, 103, 132, 179, 190, 206, 207 Viewpoint Dome, 259 vine, 134, 147, 151, 153 visitor center (Enchanted Rock), 10, 218 volcanic field, 49, 56 volcanic island arc, 49, 63–66, 68 Waco, 15 wall rock, 56 Walnut Springs Creek, 10, 78, 96, 98, 115, 136, 138, 139, 151, 193, 207, 208, 224 Walnut Springs Loop Trail, 259 warm front, 108–110 Washington-on-the-Brazos, 19 wasp, 137 Watch Mountain, 53 Waterfall Creek, 259 water staining, 72, 88, 90 water vapor, 98, 99 weathering, vi, ix, xi, 1, 57, 58, 65, 68, 71, 73–77, 81–85, 90, 91, 94, 129, 136, 191 weathering pan. See weathering pit weathering pit, 86, 87, 89, 90, 103, 128, 129, 132–134, 147, 256 Webster, James, 31 Welgehausen (Family), 11 Welge sandstone, 46 Western Interior Sea. See Cretaceous Seaway West Little Rock Dome, 83, 259 West Texas, 1, 7, 9, 15, 44, 45, 66, 69, 95, 107, 110, 255, 257 index

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wet lapse rate, 119 whiptail, 204 Whitehouse, Eula, 128, 131 Wilberns Formation, 46 winter, 92, 94, 95, 97–99, 101, 102, 104, 110, 114, 151, 207, 211, 239 wintering ground, 123 Wolf Mountain Pluton, 67

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wolves, 142 woodland, 142 xenolith, 56, 59, 61 xeric, 96, 97, 128, 142 xerosere, 128, 129 Yosemite National Park, 82, 83 yttrium, 32

Yucatan, 50 yucca, 97, 174 yucca giant skipper, 213 zinc, 32 zircon, 57 zonal flow, 104 zone (metamorphism), 61 zone (plant). See plant zone

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