Troubled Waters: Understanding the Science Behind our Coastal Crisis [1st ed.] 9783030523824, 9783030523831

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Springer Climate

Stephen J. Culver  Editor

Troubled Waters

Understanding the Science Behind our Coastal Crisis

Springer Climate Series Editor John Dodson Institute of Earth Environment, Chinese Academy of Sciences,  Xian, Shaanxi, China

Springer Climate is an interdisciplinary book series dedicated to climate research. This includes climatology, climate change impacts, climate change management, climate change policy, regional climate studies, climate monitoring and modeling, palaeoclimatology etc. The series publishes high quality research for scientists, researchers, students and policy makers. An author/editor questionnaire, instructions for authors and a book proposal form can be obtained from the Publishing Editor. Now indexed in Scopus® ! More information about this series at http://www.springer.com/series/11741

Stephen J. Culver Editor

Troubled Waters Understanding the Science Behind our Coastal Crisis

Editor Stephen J. Culver Department of Geological Sciences East Carolina University Greenville, NC, USA

ISSN 2352-0698     ISSN 2352-0701 (electronic) Springer Climate ISBN 978-3-030-52382-4    ISBN 978-3-030-52383-1 (eBook) https://doi.org/10.1007/978-3-030-52383-1 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

For family Devinder, Katherine, David, Steve, Jessy, Will, Andie, Alice, Len, Aimee, Dave, Lew, Michelle, Jasvinder, John, Boo, Darshan, Ajit, Bill, NooNoo, Jasmine, Mira, Mike, Diana, Andy, Jo, Matt, Stephanie, Georgia, Brianna, Scarlett, Olive, Anyu, Millie, and Ben.

Preface

Academic geologists spend their careers educating future generations of geologists. We are also quite good at communicating with other geologists about our scientific research. We do it through the publication of research papers in peer-reviewed journals and through presentations at conferences attended by other geologists. Unfortunately, we are not quite so good at communicating our results and their implications to politicians, policy makers, and the public. In this book we try to correct this situation to some small degree for the very relevant subject of coastal geology. Several of our chapters concentrate on coastal North Carolina, USA (it is the natural laboratory where many of the authors have worked), but the information we convey is relevant to many other coastal systems worldwide. Thus, we include several chapters that deal with coastal systems (the coastal plain to the inner shelf) beyond the boundaries of North Carolina, in Malaysia, the Basque Country, the Western Pacific, Gabon, Wales, the Caribbean, Tanzania, Russia, Papua New Guinea, the Philippines, the Maldives, Alaska, Hawai’i, Louisiana, Florida, Oregon, and Georgia. Several authors also mention older coastal systems, up to 450 million years old. New approaches to collecting coastal geologic and oceanographic data are also treated in a couple of chapters and we recognize the importance of education of students in coastal matters in another chapter. Most importantly, we try to present the human side of geologists’ work. How we conduct research, how scientific knowledge evolves as new data become available, and how we, unfortunately, sometimes take missteps along the way are all included. Our hope is that readers will come away with a better understanding of coastal systems, field and laboratory-­ based geologic research, and the people who conduct it. Because approximately 25 million of the world’s population (~7.8 billion people) currently live on land less than 1 m above high tide level (Kulp and Strauss, 2019), and that proportion has been growing, an enhanced understanding of coastal evolution, coastal processes, and anticipated future coastal change, together with a greater understanding of geologists’ research efforts (and our foibles), is relevant to us all. I wrote much of the paragraph above in June 2018. In October 2018, the Intergovernmental Panel on Climate Change (IPCC) distributed a special report entitled “Global Warming of 1.5 °C.” This report, based on extensive scientific data, vii

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explains the impacts of global warming of 1.5 °C above pre-industrial levels, what we should do about the threat of climate change, and when we should do the necessary things to avoid what can only be called global catastrophe. In the months that have followed (I am writing this paragraph in August 2019) we hear more and more serious commentators, and, indeed, the leaders of many countries, accept the fact of climate change and its (unfortunately) mind-blowing threat to humanity. As the father of two great kids and grandfather to two perfect (of course) baby grandchildren, this threat is very real to me—as it should be to all of us. As a geologist, I knew of this threat when this book was conceived in the summer of 2017, but the fall 2018 IPCC report really focuses the mind and spells out the dangers of doing nothing, or not enough, or not soon enough. So, the chapters in this book take on a little more significance. They are geological in scope and they deal with coastal matters. We hear in these chapters the backstory of scientists trying to understand coastal systems around the world so we can inform those who manage these incredibly valuable natural resources. Geologists study past coastal areas that are preserved in the subsurface and also study the processes that take place in modern coastal settings. When you read in these chapters about sea-level rise, multiple powerful hurricanes, coastal erosion and flooding, saltwater intrusion, barrier island breakdown, anthropogenic coastal pollution, tsunami, and the death of coral reefs— the modern version of the canary in the coalmine, keep in mind the fact that if we humans do not act appropriately, and very soon, to reduce the rate and amount of global warming, things will only get worse. The economic costs of projected global warming will be far greater than the economic costs of reducing carbon emissions so that the Earth does not warm 1.5 oC or more. It takes a long time to get a multiauthored book from conception to publication. So I am putting the finishing touches to this preface in the midst of the COVID-19 global pandemic. The public reaction to the virus has been unprecedented. Individuals and local, state, and national governments have joined together to fight against a ruthless and unknown threat to our way of life. I have no doubt that the doctors and scientists will find a way to combat and control the disease. Unfortunately, there is a far greater threat to humanity, and that is the anthropogenically forced global warming that drives climate change, the root cause of our coastal crisis that we discuss in this book. The effects of climate change, however, are many and go far beyond the threats to our coasts. Spread of disease, social unrest, social breakdown, and conflict readily come to mind as we battle COVID-19. But floods, droughts, crop failures, and myriad other challenges, many of them economic, will also occur. These issues are interrelated by the commonality of global warming. Indeed, the Earth is a system, analogous to a human body, but threatened by the “virus” of climate change. Perhaps we should consider the Earth to be elderly (it is 4.6 billion years old) and immunosuppressed (by the impact of humans and their burgeoning population, mainly since the Industrial Revolution). We must come together once more as individuals and local, state, and national governments to fight

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against global warming, an existential threat to the future of humankind. Individual responses are valuable, but not enough. Governments must act, and act in unison. And our responses should always be informed by science and driven by a communal caring for all of the inhabitants (not just human) of our third rock from the Sun. Greenville, NC, USA  April, 2020

Stephen J. Culver

Reference Kulp SA, Strauss BH (2019) New elevation data triple estimates of global vulnerability to sea-level rise and coastal flooding. Nat Commun 10:4844. https://doi. org/10.1038/s41467-019-12808-z

Contents

1 A Cautionary Scientific Tale and an Introduction to This Book ��������    1 Stephen J. Culver 2 Buried Secrets of the North Carolina Coast, USA��������������������������������   15 David J. Mallinson 3 Time and Tide Wait for No Man������������������������������������������������������������   33 Andrew C. Kemp and Benjamin P. Horton 4 Barrier Island Breakdown: The Ephemeral Outer Banks of North Carolina ������������������������������������������������������������������������   55 Stephen J. Culver 5 A Different Kind of Sea-Level Story from Malaysia����������������������������   69 Peter R. Parham 6 What Lies Beneath? Revealing Coastal Processes Through Mapping������������������������������������������������������������������������������������   93 J. P. Walsh 7 The Anthropocene, Wait, What? A Basque’s Coastal Experience Helps to Figure It Out���������������������������������������������������������  109 Eduardo Leorri 8 A Tale of Two Hydrogeology Problems in Coastal North Carolina ����������������������������������������������������������������������  123 Alex K. Manda 9 Drilling the North Carolina Coastal Plain – Discovering What Lies Beneath����������������������������������������������������������������������������������  137 Kathleen M. Farrell 10 Earthquake-Driven Coastal Change: Ghost Forests, Graveyards and “Komodo Dragons” ����������������������������������������������������  151 Andrea D. Hawkes xi

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11 A Scientist’s Personal 70-Year Discourse with Past, Present and Future Coastal Change������������������������������������������������������  169 Stanley R. Riggs 12 Climate, Sea Level, and People – Changing South Florida’s Mangrove Coast ��������������������������������������������������������������������������������������  189 G. Lynn Wingard 13 Pictures from Space and Feet in the Mud: Understanding the Value of the World’s Changing Mangrove Forests ������������������������������������������������������������������  213 David Lagomasino 14 What Is Happening to the World’s Coral Reefs?����������������������������������  233 Pamela Hallock 15 The Water, the Coast, the Future������������������������������������������������������������  253 Joy Moses-Hall 16 Afterword: The Power of the Ocean������������������������������������������������������  259 Stephen J. Culver

Contributors

Stephen J. Culver  Educated at the University of Wales (Swansea), Steve Culver taught for 2 years at the University of Sierra Leone before moving to the USA in 1978 on a Postdoctoral Fellowship at the Smithsonian Institution. Except for a 5-year sojourn at the Natural History Museum, London, in the 1990s, Culver has taught and conducted coastal research for over 30 years at Old Dominion University and East Carolina University. He is coeditor of a textbook on biotic response to global change over the past 135 million years and coauthor of a popular text on coastal change in North Carolina, USA. His recent research has utilized microfossils (foraminifera) as tools to reconstruct and understand past as well as current coastal environmental change in North Carolina and peninsular Malaysia.  Department of Geological Sciences, Thomas Harriot College of Arts and Sciences, Graham, East Carolina University, Greenville, NC, USA Kathleen  M.  Farrell  Educated in sedimentary geology at the University of Rochester, the Virginia Institute of Marine Science, and Louisiana State University, Kathleen Farrell taught sedimentary geology at Old Dominion University in Virginia for 2 years. After this, she became Senior Coastal Geologist at the Georgia Geologic Survey, moving to the North Carolina Geological Survey in 1991. Farrell is Senior Geologist for Coastal Plain, Stratigraphy, and Geomorphology disciplines in NC. Throughout her career, Farrell has conducted research to understand how modern and ancient geologic environments such as barrier islands and river systems evolve over time and form geologic deposits that may be economically valuable.  North Carolina Geological Survey, Raleigh, NC, USA Pamela  Hallock  Educated in ecology and oceanography at the Universities of Montana and Hawaii, Pam Hallock taught earth sciences for 5 years at the University of Texas of the Permian Basin before joining the University of South Florida Marine Science Faculty in 1983. She conducts research on environmental conditions that support modern coral reefs, on how environmental changes can terminate accretion

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of modern as well as ancient reefs, and on how human activities are altering warmwater coastal ecosystems worldwide.  College of Marine Science, University of South Florida, St. Petersburg, FL, USA Andrea  D.  Hawkes  After completing B.Sc. and M.Sc. degrees at Dalhousie University in Halifax, Nova Scotia, Canada, Andrea Hawkes moved to the USA in 2004 to pursue a Ph.D. in Earth and Environmental Sciences at the University of Pennsylvania in Philadelphia, PA. Following a 3.5 year postdoctoral appointment at Woods Hole Oceanographic Institute, Hawkes moved to University of North Carolina Wilmington where she continues her 16 years of research on reconstructing coastal change, with a focus on coastal hazards in the USA and abroad.  Earth and Ocean Sciences Department and Centre for Marine Science, University of North Carolina Wilmington, Wilmington, NC, USA Benjamin  P.  Horton  Ben Horton is the Chair of the Asian School of the Environment at Nanyang Technological University (NTU), Singapore. He was previously a Professor at Rutgers University and an Associate Professor at the University of Pennsylvania. Horton obtained his B.A. from the University of Liverpool, UK, and Ph.D. from the University of Durham, UK. His research concerns sea-level change. He aims to understand and integrate the external and internal mechanisms that have determined sea-level changes in the past, and which will shape such changes in the future.  Asian School of the Environment, Earth Observatory of Singapore, Nanyang Technological University, Singapore, Singapore Andrew  C.  Kemp  Andy Kemp completed his undergraduate education at the University of Durham (UK) before moving to the University of Pennsylvania where he completed a Ph.D. in Earth and Environmental Science. This was followed by a 3 year postdoctoral appointment at Yale University, after which he joined the faculty at Tufts University. His research focuses on reconstructing relative sea level changes that occurred during the past ~5000 years with the goal of understanding the physical processes that cause sea level to vary across space and through time. This field and laboratory-based work has spanned North America, Asia, Europe, the Middle East, and Oceania.  Department of Earth and Ocean Sciences, Tufts University, Medford, MA, USA David Lagomasino  Growing up in South Florida, David Lagomasino had a fascination with the beach, coastal wetlands, and mangrove forests. David earned three degrees in Geological Sciences, a B.S. from Florida International  University, an M.S. from East Carolina University, and a Ph.D. from Florida International University. After completing his Ph.D., David continued his research at NASA Goddard Space Flight Center, near Washington, DC.  Now David is an Assistant Professor in the Department of Coastal Studies at East Carolina University and continues to study coastlines around the world.  Coastal Studies Institute, East Carolina University, Wanchese, NC, USA

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Eduardo Leorri  Educated at the University of the Basque Country (Spain), Edu Leorri received postdoctoral fellowships that took him to Newark (Delaware, USA), Angers (France), and Lisbon (Portugal) before arriving at East Carolina University (North Carolina) in 2009. Over two decades, Leorri has conducted coastal research focusing at time scales that span the Quaternary period, including the Holocene, but with a special emphasis on the Anthropocene. His research has utilized a multidisciplinary approach that includes micropaleontology (foraminifera and their shell chemistry), organic and inorganic chemistry, magnetic susceptibility, and sedimentology, among others, and various dating techniques to understand coastal evolution at different time scales and anthropogenic impacts on coastal systems.  Department of Geological Sciences, Thomas Harriot College of Arts and Sciences, Graham 101, East Carolina University, Greenville, NC, USA David  J.  Mallinson  Educated in geology and marine science at East Carolina University (B.S. and M.S.) and the University of South Florida (Ph.D.), Dave Mallinson taught at Emory University, worked as an environmental consultant, and was a Research Scientist at University of South Florida before joining the faculty at East Carolina University in 2000. Mallinson has conducted coastal and marine research on a wide range of topics related to the processes that drive climate, oceanographic, and coastal changes through time. His most recent work uses geophysics and core data to understand the evolution of coastal systems in response to rapid sea-level change and storm impacts.  Department of Geological Sciences, Thomas Harriot College of Arts and Sciences, Graham 101, East Carolina University, Greenville, NC, USA Alex K. Manda  Alex Manda earned his Bachelor’s degree in Geology from Cardiff University (UK) and his Master’s Degree in Geology from Florida International University. He obtained a Ph.D. in Geosciences from the University of Massachusetts  – Amherst where he specialized in the hydrogeology of fractured rocks. Manda’s research focuses on investigating groundwater–surface water interactions, studying coastal hydrogeology, and assessing the influence of environmental change on water resources in coastal regions. He has taught various university courses that include Groundwater Modeling, Groundwater Hydrology, and Hydrogeology and the Environment.  Department of Geological Sciences, Thomas Harriot College of Arts and Sciences, Graham 101, East Carolina University, Greenville, NC, USA Joy Moses-Hall  Joy Moses-Hall teaches physics, astronomy, and Earth science at Pitt Community College, North Carolina, and teaches oceanography and geology at East Carolina University. She has a Ph.D. in Oceanography from the University of Delaware, a Master’s degree in Physical Oceanography from Old Dominion University in Virginia, and a Bachelor’s degree in Liberal Studies from the University of the State of New York (now Regents University). She is a science columnist for the Daily Reflector and is the author of the novel Wretched Refuge.  Math and Physics Department, Pitt Community College, Greenville, NC, USA

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Peter R. Parham  Peter Parham has Bachelor’s (Beloit College) and Master’s (East Carolina University) degrees in Geology and a Ph.D. in Coastal Resources Management (East Carolina University). His coastal research with Universiti Malaysia Terengganu and Earth Observatory of Singapore covered many areas of SE Asia. Parham conducted coastal surveys for NOAA in the Gulf of Mexico during the Deepwater Horizon oil-spill response. Prior to completing his degrees, he conducted extensive geological fieldwork in the lake country of SW Ontario and managed ranches in Montana.  US Army Corps of Engineers, Conchas, NM, USA Centre of Tropical Geoengineering, Universiti Teknologi Malaysia, Jalan Universiti, Johor Bahru, Malaysia Stanley R. Riggs  Stan Riggs is presently Distinguished Professor of the College of Arts and Sciences and Distinguished Research Professor of East Carolina University. He has degrees from Beloit College, Dartmouth University, and University of Montana. As a coastal-marine geologist, Riggs has been doing research on ancient and modern coastal systems since 1964. His recent research focuses on the interrelationship of environmental dynamics with development of human civilization. Riggs is founder and president of a non-profit 501 (c) 3 titled “North Carolina Land of Water” (NC LOW).  Department of Geological Sciences, Thomas Harriot College of Arts and Sciences, Graham 101, East Carolina University, Greenville, NC, USA J. P. Walsh  Educated in geology at Colgate University (B.A.), marine science at Stony Brook University (M.S.), and oceanography at the University of Washington (Ph.D.), J.P.  Walsh conducted 2  years of postdoctoral research at the Scripps Institution of Oceanography and was on the faculty at East Carolina University for 14 years, where he taught and engaged in research on North Carolina, the Gulf of Mexico, Puerto Rico, New Zealand, and France. In 2017, Walsh became a Fulbright Research Scholar at the Université de Bordeaux. He moved to the University of Rhode Island in 2018 to be Director of the Coastal Resources Center. His research uses a variety of remote sensing and sampling approaches to study coastal and marine sedimentary processes in the USA and around the world.  Coastal Resources Center, Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA G. Lynn Wingard  Lynn Wingard received her Bachelor of Science degree from the College of William and Mary and her Master’s and Ph.D. degrees in geology from George Washington University. She began working at the U.S.  Geological Survey as a student intern while at George Washington, and after completing her degree she was hired as a Research Geologist. Her research focuses on reconstructing past conditions in coastal ecosystems over the last 5000 years, using mollusks and the sedimentary record preserved in cores. Much of her recent work has been in support of the Greater Everglades Ecosystem Restoration.  Frances Bascom Geoscience Center, U.S. Geological Survey, Reston, VA, USA

Chapter 1

A Cautionary Scientific Tale and an Introduction to This Book Stephen J. Culver

Abstract  The unplanned collection of a small, nondescript rock in Senegal, west Africa leads to a story of how science and the acquisition of new knowledge does not necessarily progress in a series of straightforward steps. This cautionary tale is followed by an introduction that explains the purpose and content of this book, to explain to the general public, politicians, managers and policy makers how our coasts, important to us as places of not only inhabitation and vacation but also of natural resources and industry, are in crisis, in large part due to human activities. The human side of scientific research is emphasized and this book describes how geologists try to understand the workings of our varied coastal systems and what the future will bring for these beautiful and often wild parts of our planet. Keywords  Senegal · Sierra Leone · Late Precambrian · Shallow marine glacial deposits · Aldanella · Geologic research · Modern coastal environments · Climate change · Anthropogenic · Mitigating coastal hazards

A Cautionary Tale Serendipity is a wonderful thing. It has certainly been a part of my research career. I’m a paleontologist who specializes in the study of microfossils. But I have conducted research on other matters. My first job after graduating from university was as a Lecturer (the British version of an Assistant Professor) at the University of Sierra Leone in West Africa. I held that post from 1977 to 1978 and began a life-­ long interest in the geology of West Africa. By 1984 I was teaching at Old Dominion University in Virginia. That year I led a National Geographic Society-funded S. J. Culver (*) Department of Geological Sciences, East Carolina University, Greenville, NC, USA e-mail: [email protected] © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 S. J. Culver (ed.), Troubled Waters, Springer Climate, https://doi.org/10.1007/978-3-030-52383-1_1

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expedition to Sierra Leone, Liberia and Senegal, West Africa. It was a very small expedition, just me, a graduate student and a French geologist from Cheikh Anta Diop University (also known as the University of Dakar), Senegal. Early one morning I was sitting on a large rock in the Walidiala Valley, in the far southeastern corner of Senegal, 600 kilometers from the coastal capital city of Dakar and within a stone’s throw of Guinea, watching my student climbing up the steep hillside in front of me slowly and carefully logging (graphically describing) the various kinds of sedimentary rocks over which he was scrambling while my French colleague collected samples. It was hot, of course, and the air was still. I stood up to walk over to a tree under which I’d left my backpack and water bottle. We carried a lot of water and so our backpacks were somewhat of a burden even though we were only a mile or two from our Land Rover. Unfortunately, our packs became heavier rather than lighter as the day progressed because we replaced the water with rocks! These were specimens that my student and I were taking back to our home laboratory in the US to study and describe in detail. I drank deeply and in the shade of the tree I took off my hat in the futile hope that a little air to the head might cool me down. As I walked back to my seat, perhaps because I had removed my hat, the sunlight reflected off a small rock and it caught my eye. It was light in color, a buff-grey, in sharp contrast to the rocks on the floor of the valley that had a reddish tinge to them. I picked it up. It was quite nondescript, maybe 10  cm in length and width and 3 or 4 cm in thickness (Fig. 1.1). For some reason I placed it in a canvas sample bag and put it in my backpack. I carefully recorded its location in my notebook and did not give it another thought for several weeks. Our Senegalese samples that we had dispatched in a wooden box via sea freight finally arrived in the US about two months after our departure to cooler climes. My student excitedly prized open the box and sorted out his samples. And there was my little light-colored rock. The goal of our research was to build upon research I had conducted while living in Sierra Leone. We were seeking rocks that had originally been deposited by coastal and shallow marine glacial processes as much as 635 Fig. 1.1  The sample of dolostone from the Walidiala Valley, southeastern Senegal that yielded two early Cambrian fossils of the enigmatic species, Aldanella attleborensis. Pen for scale. (Image by Laura de Sousa)

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Fig. 1.2  The author standing on and next to late Precambrian, shallow marine, glacial sedimentary rocks (laminated sandstone and shale with ice-rafted dropstones) in the Walidiala Valley, Senegal. (Image by A.W. Magee)

Fig. 1.3  Close-up of the rocks illustrated in Fig. 1.2 showing a large dropstone that fell from the base of a melting iceberg and landed on the seafloor bending and disrupting underlying sediment laminations. (Image by S.J. Culver)

(maybe as little as 560) million years ago. At that time, in the late Precambrian (modern terminology is Neoproterozoic), what is now West Africa, including the countries of Liberia and Senegal, was located over the South Pole. Continental drift, powered by the processes of plate tectonics, much later moved West Africa to its current location just north of the equator. To this day, I use specimens of these shallow marine rocks deposited around the margins of a huge ice sheet that covered the northern part of the frigid West African continent as incontrovertible evidence of climate change (Fig. 1.2). By comparing the characteristics of these rocks with the characteristics of sediments deposited in coastal and shallow marine environments around Antarctica today, we can see no difference except for the fact that the African rocks are hard (Fig. 1.3) and the Antarctic sediments are soft. No other environment

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Fig. 1.4  Late Precambrian tillite from Sierra Leone. (Image by S.J. Culver)

Fig. 1.5  Late Precambrian tillite from the Walidiala Valley, Senegal. (Image by S.J. Culver)

on the surface of the Earth today exhibits sediments with same characteristics as those of shallow marine glacial environments. Thus, we use one of the basic tenets of geology, “The Present is the Key to the Past”, to interpret the environment of deposition of ancient rocks. These interpretations are valuable. For example, while I was teaching at the University of Sierra Leone, I studied late Precambrian conglomerates that had been investigated for gold deposits. The general consensus was that the conglomerates, poorly sorted sedimentary rocks composed, in this case, of sand, pebbles, cobbles and boulders up to a meter across, were deposited on the beds of rivers during the late Precambrian. Taking that idea a step further, it was thought that detrital gold might be concentrated under the pebbles and cobbles as is the case with classic placer deposits. But no gold had yet been found. By demonstrating that the conglomerates (Fig. 1.4) were glacial in origin rather than fluvial in origin, I explained why no one had struck it rich. The hydrodynamic processes that concentrate gold particles under pebbles and cobbles on the bed of a river just do not take place under a continental ice sheet or just offshore of its margins in coastal and shallow marine environments. These conglomerates were, in fact, tillites, the lithified and ancient version (see an example from the Walidiala Valley, Senegal; Fig.  1.5) of the

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extensive tills that were deposited under a great ice sheet in the northern states of the US and in northwest Europe during the maximum advance of the last ice age approximately 20,000–18,000 years ago. But let’s get back to my little buff-colored rock. I looked at its surface under a microscope and thought it might be a limestone. But it did not fizz when I dripped a little dilute hydrochloric acid upon it. It was, in fact, dolostone, a rock that is similar in composition to limestone, but which contains magnesium. I would have preferred a limestone because limestones often contain fossils. However, limestones that later become dolomitized can preserve fossils within them and so I was still interested in this specimen. Just for the fun of it, I carried my rock to a paleontologist colleague who worked at the US Geological Survey in Washington, D.C. to look for fossils. An expert in ancient molluscs (snails, clams and their relatives), he processed it by quenching – alternating hot and cold until the rock fractured and broke. And lo and behold, two tiny fossils popped out! They were internal molds (lithified sediment infilling) of coiled snail shells preserved as phosphate and each one no bigger than a pin-head (Fig. 1.6). Similar shells, called Aldanella, had been described from Siberia and Newfoundland and they indicated that the rock I had collected in Senegal containing them had been deposited early in the Cambrian Period approximately 530 million years ago. So now I had a big problem. By pure chance, the serendipity that I spoke of at the beginning of this story, I had found some fossils that were of some importance. This type and age of fossil had not been recorded previously in this part of West Africa. Thus, their presence was of significance for both dating the rocks and for understanding their paleogeographic distribution. But I did not know exactly where the fossils were from! I had not collected my little rock from its source. I had not hammered it off a cliff face of solid rock. My rock was from the “float”, the collection

Fig. 1.6  Three scanning electron microscope images of a specimen of the early Cambrian fossil Aldanella attleborensis from the Walidiala Valley, Senegal. Scale bars are 500 micrometers. (Images by SJ. Culver and L. De Sousa; from C.R. Acad. Sci. Paris, t. 307, Serie II, p. 651–656, 1988)

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of loose rock of all sizes that had either fallen down the valley side under the force of gravity or had been transported along the valley floor by running water during a rainy season in the not too distant past. The 635 million year-old glacial rocks sat directly upon older limestone and sandstone that together with 2 billion year-old metamorphosed basement rock of granitic composition floored the valley. So, where did my dolostone come from? Its source must have been from higher up the side of the valley – but the sedimentary logs did not record any dolostone. With my student, I had climbed up the valley side, which was partially covered by dense scrub, to check his work and I too did not see any dolostone. Overlying, and therefore younger than the glacial rocks, were red and green siltstones, with an interbedded approximately one meter-thick greyish colored chert, a very hard rock with the same composition as quartz. Overlying the siltstones was a much younger almost black rock called diabase. This dark, hard, igneous rock, which had protected the underlying sedimentary rocks from erosion, was intruded at shallow depths in the Earth’s crust as a result of fracturing and faulting of rock during break-up of the supercontinent Pangea early in the Jurassic Period approximately 190 million years ago. The region that is now Senegal, Gambia, Guinea-Bissau, Guinea and Sierra Leone rifted away from what is now eastern Florida and Georgia as the continents of Africa and North America began their slow journeys that resulted in a 7000 kilometer-wide Atlantic Ocean. Indeed, the rocks deep in the subsurface below the Everglades of Florida are the same as those exposed on the surface in Sierra Leone today. If my rock was not from the valley sides, then it must have been transported down the river valley. I needed to go back to Senegal to walk up the valley to find the source, not of the ephemeral river that carved the valley over tens of thousands of years, and perhaps much longer, but of the fossils in my little buff-colored rock. I wrote another proposal, this time to the National Science Foundation, and a couple of years later I returned to the Walidiala Valley, this time with two colleagues from the U.S. Geological Survey. On arrival I saw immediately that the place had changed dramatically. The dense brush that had covered the valley sides had been burned off (Fig. 1.7), perhaps by wildfires but more probably by the local villagers in order to expand the area where crops could be planted. And there, at the same

Fig. 1.7  A hillside in the Walidiala Valley, Senegal showing burnt vegetation in the left foreground and geologists moving past newly exposed rock outcrops (Image by J. Repetski)

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elevation on both sides of the valley was a horizontal buff-colored rock unit, a little scorched from fire, from 1 m to 7 m in thickness, above the glacial rocks. I was both surprised and extremely happy to see this. This must be the source rock for my little snail shells! A couple of years earlier, my student and I had climbed up the hillside and had, by chance, chosen a route through the brush that happened to be over a thin part of the dolostone where it was hidden by vegetation. With this new knowledge about the source of my “float” rock, I could now submit a research paper describing and illustrating these fossils to a peer-reviewed scientific journal. After review and editorial comments my coauthors and I revised the paper and a year or so later it was finally published.

An Introduction to This Book So why have I recounted a cautionary scientific tale? Well, first of all, the only people who read my paper on the fossils I had found in the Walidiala Valley were fellow paleontologists interested in the early Cambrian when many groups of animals and various kinds of single-celled organisms first acquired hard parts, in this case, coiled shells. In other words, we scientists communicate through our publications in specialized journals with liked-minded people with similar interests. Most of what scientists publish is never seen let alone read by anyone else. The proverbial “man in the street” has little idea what scientists are doing and why the many avenues of research might be important. Indeed, importance, is not always self-evident. Remember, for example, the conglomerates in Sierra Leone and the lack of gold. Second, you’ll see that serendipity is a big part of this story. It was by chance that I picked up my little buff-colored rock. It was by chance that my student and I missed the source dolostone during our traverse up the valley sides. I had not planned for returning to a valley almost devoid of vegetation. And I’m sure chance had something to do with my grant proposal being funded. I could have received reviews from anonymous scientists who did not like what I had written. But, instead, the reviews were good, and I received the funding that enabled me to return to my field site. It was also by chance that I knew paleontologists at the U.S. Geological Survey who could collaborate with me. And that was the result of my being a post-­ doctoral researcher in the Department of Paleobiology at the Smithsonian Institution at a time when the Survey’s paleontologists were housed in the Smithsonian’s Natural History Museum along with Paleobiology’s paleontologists. This was the result of a (successful) effort to encourage collaboration between the paleontologists of two of the most important scientific institutions in the US. Third, you’ll understand now that the research I published on the little snail shells was not only the result of chance finds but that it was the result of basic, curiosity-driven science. That is one way to undertake research, but it is well removed from what we are taught about at school – the scientific method. Geologists are expected nowadays to undertake hypothesis-driven research. The geologist develops a hypothesis about a topic of interest, often based on previously conducted

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research. S/he then tests the hypothesis by trying to falsify it. It is possible to falsify a hypothesis, but it is not possible (in geology, usually) to prove a hypothesis. Take, for example, the hypothesis that all ants have six legs. One cannot prove that is the case because it is not possible to count the legs on every ant that is alive today and, of course, the legs on every ant that was alive in the past. Now consider the hypothesis that all sheep are white. Observations are then made, and one single observation of a black sheep falsifies the hypothesis. This then leads to the next, interesting scientific question, “Why are some sheep are black?” Fourth, this book will, hopefully, demonstrate the fact that geologic research, like any other endeavor, has a human side. We all have our styles, strengths, weaknesses, and foibles. And, of course, we can all make mistakes. One fact that pleases me, even though I have disagreed, sometimes strongly, with other scientists, is that in 46 years of undertaking geologic research I have not come across a single case of a fellow geologist being willfully misleading in his/her research activities. That is a pretty strong statement and one that should give us all much comfort. It is very important to point out, however, that this does not mean that we should not question scientists’ research and conclusions. As I suggested in the Preface, we should all do a little research, nowadays probably on the web (making careful judgements on the veracity of sites we visit), and in doing so allow ourselves to make educated judgements on what to accept, what to question and what to reject. And our acceptance, questioning and rejection should be based on data and not belief. In summary, geologic research, often involving a significant field component, can be exploratory and descriptive or it can be hypothesis-driven. Either way, science progresses. New scientific data can often answer a question and lead to one or more new scientific questions. Scientists rarely have all of the answers. We are always learning new things. It is understandable, therefore, when other professionals, such as environmental managers or policy makers, become frustrated by the diffidence of scientists and their unwillingness to become dogmatic about whatever topic is the subject of discussion. This apparent “changing of the mind” can lead to accusations of “bad science” or even of scientists feathering their nests with grant funds. All you need to do is look at how most geologists dress and the cars that we drive and you’ll know that grant funds have not led to a life of luxury. What is this book about? Well, it’s not about West Africa, not about 635 million year-old shallow marine glacial deposits, and not about tiny fossils of snail shells. But it is about how geologists conduct research and progress their science. More specifically, it is about coastal geology and it is a sincere effort to communicate what coastal geologists do and why they do it. It is an effort to explain the relevance of what we do to the lives of people living in coastal communities, to the tourists who visit our shores, to the people who manage our coastal economies and, indeed, the relevance of our work to the well-being of national economies and, therefore, the populations of entire countries. The coast is the zone where the marine realm and the terrestrial realm intersect. It is a dynamic place, one that is affected by climate change and where the processes of sea-level rise and storm dynamics demonstrate the power of the ocean over the relatively long term and short term, respectively (Figs. 1.8, 1.9, and 1.10). But the coast,

1  A Cautionary Scientific Tale and an Introduction to This Book Fig. 1.8 Storm-driven erosion of a bluff on the Chowan River estuary, North Carolina. (Image by Burrell Montz)

Fig. 1.9  A back-barrier marsh on Ocracoke Island, North Carolina, showing hurricane-driven overwash sand covering much of the marsh vegetation. (Image by A.C. Kemp)

Fig. 1.10  Highway12 just north of Rodanthe, North Carolina, looking south, showing the artificial dune on the left that was overwashed by water and sand during a nor’easter. Note the location of the white dashed line down the middle of the road. In the right distance, bulldozers are clearing sand off the highway. (Image by S.J. Culver)

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defined narrowly, does not tell the whole story. The coastal zone is affected, for example, by the waters that come down the rivers and by the nature and amount of sediment that characterizes the inner shelf. In return, coastal processes can affect the characteristics of the coastal plain, for example by intrusion of saline water miles inland in surface and subsurface waters. Hence, this book documents aspects of a zone much broader than the coast, encompassing the coastal plain to the inner shelf. We have heard much in the media about climate change. The authors of this book recognize that climate change is a natural process. How can we not recognize and accept this? The entire history of the Earth that we read in the rocks is about change. Refer again to the Cautionary Tale and glacial deposits in what is now equatorial Africa. But even greater changes have characterized our Earth. For example, if you travelled in a time-machine back to the early Earth, 3.5–4  billion years ago (the Earth is ~4.6 billion years old), and you got out, you would suffer an awful but quite rapid death because the atmosphere at that time contained no oxygen for you to breathe. Free atmospheric oxygen arrived millions of years later during the Great Oxygenation Event (2.4–2.0 billion years ago) and only by about 540 million years ago did it reach concentrations high enough to lead to the evolution of the animal groups that are still with us today. So, the composition of the Earth’s atmosphere has changed since early Earth History and climate has always changed but we also now know that human activities are an increasingly important driver of current climate change. This book will not debate this fact – it has been well demonstrated elsewhere (see IPCC reports, for example). But readers of the following chapters will see that climate change is a fact of life and that the geological record of the recent past is important as it provides us with an understanding of the nature and scale of environmental changes we should anticipate in the future. Thus, we have changed around that basic tenet of geology referred to earlier in this Introduction (“The present is the key to the past”) to, “The past is the key to the future”. If our data-based projections for the future are realistic, accepting that there are uncertainties and that science progresses, our projections will become more accurate as new data are collected and new models are run. We will have a chance of adapting to the warming world mentioned in the Preface and to mitigating the coastal hazards that come our way (Figs. 1.11 and 1.12). We start the book with a chapter by Dave Mallinson that introduces the reader to coastal North Carolina, USA (Fig. 1.13) and, in particular, to what lies beneath the Outer Banks barrier islands and the sounds behind them. Andy Kemp and Ben Horton then explain the science behind sea-level studies based on research experience from all over the world. We then return to the Outer Banks and this book’s editor describes an event of major change that occurred 1200 years ago that might well happen again in the not too distant future. Pete Parham’s chapter describes his sea-level studies in Malaysia that come at the question in a completely different way from that of Kemp and Horton. Next we hear from J.P. Walsh about new ways to investigate coastal processes, including the high-tech approaches to that tried and true scientific activity, geologic mapping. Edu Leorri then recounts some of his coastal pollution research in the Basque Country and gives us his perspective on a topic de jour, the proposed new geologic interval of time known as the Anthropocene.

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Fig. 1.11  Highway 12 on Pea Island, North Carolina, looking north showing an eroded dune on the right and bulldozed sand on the left during a nor’easter. (Image by S.J. Culver)

Fig. 1.12  Houses in the ocean at Rodanthe, North Carolina, during a nor’easter storm. The house with the blue shutters featured in the movie, “Nights in Rodanthe”, starring Diane Lane and Richard Gere. The house was later moved by truck to another location. (Image by S.J. Culver)

We return to North Carolina and Alex Manda’s stories on water resource issues. Of course, the availability of water is a basic societal need – recall that the capital of South Africa, Cape Town, came perilously close to running out of water in 2018 (water levels of major dams dropped to 13.5% of capacity). The next chapter, by Kathleen Farrell, is about her experiences drilling into the subsurface of the Mississippi Delta and the Georgia and North Carolina Coastal Plain, the source for much of this region’s ground water supply. We then travel to the west coast of the US and hear from Andrea Hawkes about coastal change driven by earthquakes. Andrea then takes us back to Malaysia and describes her experiences as a graduate student studying the geologic record of the horrifying tsunami of December 2004 caused by a megathrust earthquake off Sumatra, Indonesia. We stay in warmer realms with Lynn Wyngard’s chapter on the value of coastal mangrove forests and threats to the unique Everglades environment and David Lagomasino’s chapter on remote sensing of mangrove forests in Gabon, Tanzania and the Philippines. Following is Pam Hallock’s extremely educational but, unfortunately, disturbing

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Fig. 1.13 (a–d) Maps showing the location of studies mentioned in this book 1. Pamlico Sound, Outer Banks, Roanoke Island, North Carolina, USA 2. Suffolk Scarp, Buckridge Preserve, Plymouth, Chowan estuary, North Carolina, USA 3. Florida Keys, USA 4. Florida Bay, USA 5. Mississippi Delta, Louisiana, USA 6. Coastal Georgia, USA 7. Coastal Oregon, USA 8. Coconut Island, Kaneohe Bay, Hawai’i, USA 9. Beloit, Wisconsin, USA 10. Dartmouth, New Hampshire, USA 11. Missoula, Montana, USA 12. Hamilton, New York, USA 13. Long Island, New York, USA 14. Sitkinak Island, Alaska, USA 15. Parguera, Puerto Rico 16. St. Croix, US Virgin Islands 17. West coast, Peninsular Malaysia 18. East Coast Peninsular Malaysia 19. Sarawak, Malaysia coast, Borneo 20. Sabah, Malaysia coast, Borneo 21. West coast, Thailand 22. New Britain Island, Papua New Guinea 23. Fly River Delta, Papua, New Guinea 24. Southern Negros, Philippines 25. The Maldives 26. Belau, western Caroline Islands 27. Libreville, Gabon 28. Rufiji Delta, Tanzania 29. Southeast Senegal 30. Bilbao, The Basque Country 31. White Sea, Russia 32. Swansea Bay, South Wales, UK

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chapter on the threat of global warming to the well-being of coral reefs worldwide. Stan Riggs then describes his love affair with coastal geology and education over 70 years; many, many students have had successful careers as geologists due to the things they have learned (not just geological) under Stan’s “soggy groggy” tutelage. In the penultimate chapter, oceanographer and educator Joy Moses Hall reflects on the chapters in this book and provides thoughts that will, hopefully, encourage and enable the reader to both embrace and coexist with the inevitable coastal change that will come our way. We end with an Afterword  – a brief essay by the editor that describes an unforgettable experience during his doctoral student days that greatly impressed upon him the incredible power of the oceans. It is that power, and the changes that it effects, that makes the coastal zone such an interesting and exciting place to live, work, study and play.

Important Postscript (More Caution!) I’ve noted above that science progresses. We learn new things and old interpretations might need to be modified or even rejected. Sometimes we might not like what we learn. My story about the two tiny fossil snail shells in the buff-colored rock took another turn in 2007 in a paper that I coauthored with a multinational team of geologists. In the 23 years since I had collected that rock, no other fossils had been found in samples from the dolostone outcrop (although few people had looked at those specific outcrops, similar rocks, in similar stratigraphic sequences, and of similar age, occur on several continents, and none -to my knowledge- have yielded fossils like the two I had found in Senegal). Furthermore, phosphate had not been recorded in the Walidiala Valley dolostone and yet the fossils were phosphatized. The weight of evidence led us to conclude that it was “unwise” to use the two fossils to assign an early Cambrian age for the dolostone when all other evidence suggests the dolostone was of late Precambrian age. What have I learned from this? Never pick up a loose rock! You might think that is the end of this tale, but it is not! In 2013 a research paper argued that Aldanella was not a snail (class Gastropoda, phylum Mollusca). Amazing fossils of Aldanella attleborensis from Pennsylvania and Siberia, even though they are more than 500 million years old, preserve phosphatized soft parts including hair-like structures called chaetae that were part of a locomotory organ that indicates a swimming lifestyle. These are not characteristics of early gastropods (although some tiny members of this group called pteropods began to swim in oceanic surface waters ~72–79 million years ago and continue to do so today). It was suggested in the 2013 paper that Aldanella belonged to an enigmatic group of extinct organisms called the hyoliths (class Hyolitha, phylum Mollusca). So, my tiny coiled fossils, now in the collections of the Smithsonian Institution, are not even snail shells! Serendipity can be very complicated! But we learn new things and science progresses.

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Acknowledgments  Thanks are due to Marty Buzas, Bernard Robineau, A.  W. “Pete” Magee, Dave Hunt, John Pojeta, John Repetski, the National Geographic Society, the National Science Foundation and the US Geologic Survey. I greatly appreciate the support of Dave Mallinson, Lauren Morrison, Emily Griffin, Laura de Sousa, Seth Sutton and Marah Dahn. Annett Buettner and Alexander James at Springer helped me through the process of getting this book to press. My friends who are the coauthors of this book have been great to work with. All care deeply about their research and its relevance to society.

If You Would Like More Information Culver SJ, Magee AW (1987) Late Precambrian glacial deposits from Liberia, Sierra Leone, and Senegal, West Africa. Natl Geogr Res 3:69–81 Culver SJ, Pojeta J, Repetski J (1988) First record of Early Cambrian shelly microfossils from West Africa. Geology 16:596–599 Dzik J, Mazurek D (2013) Affinities of the alleged earliest Cambrian gastropod Aldanella. Can J Zool 91:914–923 IPCC (2014) In: Edenhofer O, Pichs-Madruga R, Sokona Y, Farahani E et al (eds) Climate change 2014: mitigation of climate change. Contribution of working group III to the fifth assessment report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge/New York IPCC (2018) Summary for policymakers. In: Masson-Delmotte V, Zhai P, Portner HO, Roberts D et al (eds) Global warming of 1.5°C. An IPCC special report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. World Meteorological Organization, Geneva, p 32 Riggs SR, Ames DV, Culver SJ, Mallinson DJ et  al (2009) In the eye of a human hurricane: Oregon Inlet, Pea Island, and the northern Outer Banks of North Carolina. In: Kelley JT, Pilkey OH, Cooper JAG (eds) Identifying America’s most vulnerable oceanfront communities: a geological perspective, Geological Society America Special Paper 460. Geological Society of America, Washington, DC, pp 43–72 Riggs SR, Ames DV, Culver SJ, Mallinson DJ (2011) The battle for North Carolina’s coast: evolutionary history, present crisis, and vision for the future. University of North Carolina Press, Chapel Hill Shields GA, Deynoux M, Culver SJ, Brasier MD et al (2007) Neoproterozoic glaciomarine and cap dolostone facies of the southwestern Taoudeni Basin (Walidiala Valley, Senegal/Guinea, NW Africa). Compte rendu Geosci 339:186–199

Chapter 2

Buried Secrets of the North Carolina Coast, USA David J. Mallinson

Abstract  The Outer Banks Barrier Islands of North Carolina, USA are beautiful and dynamic coastal features with a long and complicated human history and geological story. The hard work of numerous university faculty, agency scientists and students have uncovered the geological secrets of this region. Using geophysical devices that reveal the underpinnings of the islands and estuaries, and collecting sediments and fossils to understand changes to the environments, we can see how the islands and estuaries responded to climate conditions and storm patterns in the past. Those past responses are informing us of what might be expected in the future given projected climate and sea-level changes. This is the story of the work that has been done to reveal the secrets of this coast. Keywords  Outer Banks · North Carolina · Barrier islands · Inlets · Coastal geology · Lost Colony · Sea level · Climate change

Where History and Geology Meet In 1585  A.D., the crew of an English ship first glimpsed the sparkling emerald waters, white breaking waves and endless beaches and dunes of the North Carolina coast, looking to establish an English settlement and a new life in the New World. This was the plan of Sir Walter Raleigh, a bold nobleman with close ties to Queen Elizabeth, who wanted a foothold on North America to ensure a British claim on the continent, and to have points from which to capture gold coming up the coast from the south in Spanish galleons. The captain and crew carefully navigated the ship through the Outer Banks barrier islands to the estuaries behind via an inlet, Roanoke D. J. Mallinson (*) Department of Geological Sciences, East Carolina University, Greenville, NC, USA e-mail: [email protected] © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 S. J. Culver (ed.), Troubled Waters, Springer Climate, https://doi.org/10.1007/978-3-030-52383-1_2

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Inlet, the location of which is now occupied by dry land, a strip mall, miniature golf courses, a highway, and many homes and rental properties. One of the passengers of this first expedition was Sir Thomas Harriot, an English naturalist who documented the plants and animals, and the natives of this new land, and the namesake of the Harriot College of Arts and Sciences at East Carolina University where I work. Another passenger was John White who produced the first map of the coast showing the rivers, estuaries, islands and inlets from Cape Fear NC to the Chesapeake Bay of Virginia (Fig. 2.1). He also produced wonderfully accurate watercolor paintings of native peoples, which now reside in the British Museum in London. This first expedition returned to England after only a year, leaving 15 men behind, but the die had been cast, and England was set on placing a claim in the New World. In 1587, John White, who was now appointed by Sir Walter Raleigh as Governor and Assistants of the Cities of Raleigh Virginia, returned with a contingent of 115 colonists including women and children, who found no trace of the 15 men left behind, except for the bones of one. The colonists built a fort, Fort Raleigh, on the northern point of Roanoke Island, behind the barrier islands. The location of that original fort and settlement is underwater now, destroyed, scattered and buried under estuary sands and muds, by erosion of the island shoreline; a result of the nearly 2  feet (~60  cm) of sea-level rise since 1587. The island now has two communities, Manteo and Wanchese, named after the first Native Americans to have returned to England following the first contact. A reconstruction of the fort can

Fig. 2.1  A comparison of the White-DeBry map of 1590 (left) and the modern coastal system of eastern North Carolina, USA (right; Landsat imagery – Google Earth). Arrows show the location of inlets. Eleven inlets were mapped in 1585–1590, as compared to four that are active today. CH is Cape Hatteras. CL is Cape Lookout. RI is Roanoke Island. The Outer Banks barrier islands are the long thin islands that extend from near the Virginia border in the north to Cape Lookout in the south

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be found in the Fort Raleigh National Historic Site near Manteo. This colony failed, partly because they had the misfortune of setting up shop during one of the worst extended droughts in North American recent history. We know this based on analyzing tree rings. The rings record, in their width, periods of drought versus abundant rainfall; drought produces a dense narrow ring due to poor growing conditions, while good growing conditions produce a thick ring. When John White returned to the colony after 3 years, all that was found was a carving on a fence post that said “Croatoan”, the name of a local Native tribe and nearby island (now Hatteras Island). However, the English presence continued, although in the tidewater region of Virginia at the Jamestown colony. The White map also survived and provides a historical document from over 400 years ago, to which we can compare the modern coast and see changes to the barrier islands (Fig. 2.1). Of course, there are other ways we can understand changes in the past besides historical documents. This is where coastal geology comes into play. Roughly 425  years after White and Harriot visited the coastal part of what became North Carolina, a plain white truck with a roof-rack loaded with aluminum pipes and an odd tripod rattles down Highway 12 on the Outer Banks barrier islands of North Carolina. The air shimmers with heat above the pavement and the adjacent sand dunes. One could easily fry an egg on the pavement (not that you would want to; it would just be too sandy to eat). Sand is everywhere. Patches of American Beach Grass, Sea Oats, and Sand Spur, with red, brown and yellow Sea Oxeye Daisy, dot the tan sandy landscape. Looking west over the sand flats, marsh plants, Juncus (Black Needle Rush  – aptly named for its extremely sharp points) and Spartina (Salt Marsh Grass), provide a green border at the edge of the water of the Pamlico Sound, reflecting the blue of a nearly cloudless sky. Pamlico Sound extends like a vast inland sea to the west, roughly 70 miles (112 km) long from north to south, and 20–30  miles (32–48  km) wide. It’s not surprising that early explorers believed Pamlico Sound to be the Pacific Ocean. Looking east, dunes covered with sea oats rise above the tan colored beach bordering the white foam of breaking waves and the vast expanse of the North Atlantic Ocean. Rising in the distance to the east is a line of towering thunderheads, perched over the warm waters of the Gulf Stream, a vast oceanic “river” carrying Caribbean and Gulf of Mexico waters northward and across the ocean to warm western Europe (palm trees grow in southwest England, at the same latitude as Labrador, Canada). This is the same current that the Spanish galleons would ride, and sailors would navigate back to Europe in colonial times, as well as today. It is a major artery of the ocean, transporting as much water as 500 Amazon rivers.

Boots on the Ground The van slows and pulls tentatively off the road and onto the loose sand shoulder, being careful to keep two wheels on the pavement; we learn from experience! Boots hit the ground and a student climbs to the roof. She begins unstrapping and passing

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Fig. 2.2  Photograph of students unloading the tripod for the vibracore on the Outer Banks, NC (Hatteras Island). (Image by S.J. Culver)

down the components of a device designed to recover long tubes of sediment (sand, mud, etc.) from beneath the surface of the island. This is our vibracoring system. Long aluminum tubes, some with discs on the bottom, and a platform on the top (Fig. 2.2) are handed down. Others start pulling items from the back of the van – tools and an engine with a long cable attached. Another student, who is using the data for a thesis, consults with the professor (that would be me) on our location and the anticipated geology. We record our position with a global positioning system (GPS) unit and look at some geophysical data that show the layering beneath the ground here where we stand, the results of a ground penetrating radar (GPR) survey done earlier in the season. The GPR device shoots radio waves into the ground, which are reflected back where changes occur in the sediments below the ground. The reflection is recorded and reveals the layers and buried secrets of the island, showing us what existed before today; inlets, beaches, marshes, dunes, etc. We break out various wrenches and other tools and begin the construction of a vibracore tripod on the sand flat, with which we intend to recover the layers and expose the buried secrets. It’s another day in the office for these coastal geologists. At 5 pm, everyone is tired, having been at it since 7 am, when the temperatures were more inviting. But the challenge, if only for bragging rights, is to get the most and/ or the longest cores in a day. The students are up to the challenge. The core pipe is lifted with the vibrating head clamped near the top (Fig. 2.3). The engine is started and the vibrator roars to life in an ear-piercing rattle. The core pipe rapidly sinks through the sand at first, then slows. Tourists driving by slow down and point, as if we’re another novel variety of wildlife on these islands. We wave and smile when we can. The geologists twist the vibrator and pipe, trying to force the pipe to penetrate deeper into the island sands. The objective is to recover sediments – sand, mud, shells, organic material, that occur beneath the surface and record the history of this island. Why do we expend our blood, sweat, and tears to recover a pipe full of sand? It’s all about the lure of adventure and knowledge; the knowledge being critical to

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Fig. 2.3  A vibracoring operation at Duck, NC on the northern Outer Banks. (Image by S.J. Culver)

understanding future environmental changes. We know that the salinity and energy (waves, currents, tides) varied greatly within Pamlico Sound in the past. One thousand years ago, and as recently as 500 years ago, conditions were very different than today. And we know that these changes must be related to what was happening to the Outer Banks barrier islands, so we want to know what the islands looked like in the past, where the inlets were, how many there were, when were they active, and, perhaps most important, how the changes relate to climate and sea-level changes in the past. We know that inlets opened and closed in numerous places throughout history. As mentioned before, there are maps that go back to 1585 AD, created by John White, that demonstrate where some of these inlets were, and how the barrier islands have changed since then. But we also want to know what was going on one thousand years ago, before there were any maps. To do this, we need to look at the geology.

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The Medieval Warm Period Perhaps a little history is in order, regarding what was happening one thousand years ago, to put our effort in context. The period of time, from approximately 700 A.D. to 1200 A.D., is known as the Medieval Warm Period, or the Medieval Climate Anomaly (or MCA for short; because more than just temperature changes occurred). The term Medieval might conjure up images of castles and knights in shining armor, which is accurate to a degree. During this period of time, temperatures around the North Atlantic basin were relatively warm; likely as warm as the twentieth century, although we’re exceeding these temperatures now in the twenty-­ first century. There are lots of data that support relatively warm temperatures during the MCA including historical records of the time, the extent of various types of vegetation in Europe, including crops, the extent of various types of organisms in the oceans, and geochemical data from fossils and ice cores from glaciers. Warm surface ocean waters decreased the extent of sea ice in the high North Atlantic and allowed the Vikings to explore westward and colonize Iceland, Greenland, and Newfoundland. Cultures flourished and expanded in Europe and Asia as agriculture expanded due to the warm conditions. The increase in ocean water temperature also may have increased the number and/or intensity of hurricanes at this time, based on storm deposits seen along the North American east coast, and in the Bahamas and islands in the Caribbean Sea. There is also some evidence that the rate of sea-level rise increased slightly during the MCA. All of these factors, rising sea levels, changing sea-ice conditions, hurricane activity, precipitation patterns, water temperatures, are critically important to our modern civilization. What’s more, in coastal areas, understanding how the beaches, barriers and estuaries change in response to the rising sea level and storm activity is vital to managing these areas and preparing for what the future will bring. Below the surface of the barrier islands and the estuaries, within the layers of sand and mud, we have the record of the past which informs us of what is possible in the future.

Good Morning Outer Banks We’re coring in a particular spot where we know there was once a large inlet. How do we know this? To explain, we need to rise early, 3 am, and venture out onto the deserted roads of the Outer Banks. We do this with the help of dedicated law enforcement officers who provide an escort. Why 3 am? We’ve been informed that any earlier and you may have impaired drivers on the road. And, by 7 am, the roads are becoming too busy. So, we have a short window of opportunity while most are dreaming about the waves and beaches. The officers aren’t impressed that we need to tow our GPR device (Fig. 2.4) at a mind-numbing 3–5 mph. We creep down the dark highway, illuminated only by the flashing blue lights of the police car. The radar antenna trails behind us, noisily dragging on the highway, sending signals into

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Fig. 2.4 Collecting Ground Penetrating Radar (GPR) data using a utility vehicle on the Outer Banks near Salvo, NC. The bright orange box is the GPR antenna. Data are shown in Fig. 2.5. (Image by S.J. Culver)

Fig. 2.5  Ground Penetrating Radar data (top) and an interpretation (bottom) indicating that an inlet (yellow highlighted area) occurred in this area of the Outer Banks, NC. Subsequent vibracoring and dating of the sediments tells us that it was active sometime between approximately 300 and 500 years ago

the ground, and receiving the reflections from the layers below. The reflections on the computer screen are mostly horizontal, indicating the surface layers of sand deposited as sheets when ocean waves and water washed over the island during storm events; an important process in the natural maintenance of the barrier islands. Occasionally, the reflections dip in one direction or another (Fig. 2.5), signifying that the layers were deposited within an ancient inlet channel. These provide our targets for coring. These sites have piqued our curiosity because the data show that many more inlets occurred in the past, whereas today there are so few inlets, only four, along the Outer Banks (Figs. 2.1 and 2.6). As a result, the tidal range in Pamlico Sound is minimal (around 4  inches  =  10  cm) except near the inlets themselves. Likewise, the salinity stays much lower in Pamlico Sound than in the ocean, as the Sound waters are fed by freshwater coming from the various rivers feeding into the Pamlico and Albemarle Sounds. These conditions dictate the biology in the Sound,

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Fig. 2.6  Map showing the location and ages (in years before present; cal y BP) of paleo-inlets (ancient inlets) in the Outer Banks, NC. LIA refers to the Little Ice Age that occurred between approximately 700 years ago (700 BP) and 100 years ago. MCA refers to the Medieval Climate Anomaly that peaked about 1000 years ago (1000 BP) (Mallinson et al. 2011)

including the fish and shellfish, and crabs that form the vital fisheries, so important to the economy of the region and the social fabric and way of life of the local inhabitants. As the eastern sky begins to grow brighter, and the stars begin to fade, we wrap up the survey and head back toward our little house at Jockey’s Ridge State Park to have some breakfast and coffee. Already, trucks with fishing rods mounted on the grill, and coolers in the back, begin their trek to the beach to surf cast. When we arrive, the rest of the crew are up and getting prepared for the rest of the day’s work, including the vibracoring, which brings us back to the hot sand flats where we’re working.

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More Core! We pull the core from the ground using a winch and load it up on the truck after taking careful measurements and cutting it into shorter sections. The cores, and there are many dozens of them, are transported back to the core cutting lab at East Carolina University (ECU). Here we split them lengthwise, using a circular saw and wire, and lay them open to reveal their secrets (Figs. 2.7 and 2.8), buried for hundreds of years. The sediments and layers are meticulously and methodically described and documented in a process we call core logging. Photographs are taken. Finally, samples are extracted for multiple purposes. Some of the samples are analyzed for the grain-size characteristics of the sediments, which enables an understanding of the energy of the environment where they were deposited. Other samples are analyzed for their fossil content. The fossils we look for are microfossils, tiny organisms called foraminifera (forams for short), so small that several could fit on the head of a pin. Particular species of these organisms live in discrete coastal and open marine environments, dictated largely by salinity and temperature of the water, among other things. Identifying them provides information on the ancient environment. When we analyze them in cores from the Pamlico Sound, they provide information on how much water is coming from the ocean, and thus the degree to which inlets might occur through the islands. Still other samples are analyzed to determine the age of the deposits. Shell material undergoes radiocarbon analysis, which uses the regular decay of carbon-14 within the shell mineral structure to estimate age. Quartz sand undergoes optically stimulated luminescence (OSL) analysis. This is a very complicated technique to determine the age. Upon burial, quartz sand begins to absorb ionizing energy from the decay of radioactive elements in the soil. When recovered and exposed to light in a laboratory setting, the samples will luminesce, shedding that ionizing energy. The amount of luminescence is related to how long the sample has been buried. With these techniques we can place environmental changes in the context of time, Fig. 2.7 Students sampling a core in the core cutting laboratory at East Carolina University. (Image by E. Leorri)

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Fig. 2.8  A closeup photo of a split core showing layers of sediment which hold the key to understanding coastal change. The scale is in centimeters. (Image by D. Mallinson)

and to other known climate changes in the past, thus helping us understand the processes that drive change in these coastal environments, and how they will respond to future climate change. The barrier islands are not the only place we work to understand the changes affecting the coast. Our research takes us on the water as well. We have spent years traversing, mapping, and sampling the estuaries of eastern North Carolina. Pamlico and Albemarle Sounds are the largest, but the smaller estuaries, for example Croatan, Roanoke and Currituck sounds, near to Albemarle Sound (Fig. 2.1) and Core Sound, south of Pamlico Sound (Fig.  2.1), also contain secrets. Much of the work has involved surveying the seabed and the layers of sediment below and collecting bottom samples and cores.

Reflecting on Rising Seas We depart the dock in Washington, NC shortly after sunrise and navigate the R/V Stanley R. Riggs, a 34-foot aluminum craft built for just this type of work, to the larger reaches of Pamlico Sound to begin a survey. Following an invigorating high-­speed cruise propelled by twin Volvo diesel engines, we slow to walking speed and deploy a three-foot long yellow submarine-looking device called a CHIRP (Compressed HighIntensity Radiated Pulse) subbottom profiler (Fig.  2.9). This device sends highlytuned sound energy of multiple frequencies through the water column and into the underlying sediment every half second. The sound is much like the chirping of a bird. It rises quickly from low frequency to high frequency in every half-second cycle. The energy enters the sediment and an echo is reflected back up toward the surface wherever a change is encountered in the density of the sediment and the velocity of the sound. That echo (or “reflection”) is then received by the CHIRP profiler, transmitted up a cable, amplified, digitally sampled by a computer, and shown on a computer screen. The result is an image of the layers of sediment beneath the seafloor (Fig. 2.10). The images that are revealed remind us of the incredible changes that the Earth has undergone as sea level has fallen and risen multiple times over tens to hundreds

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Fig. 2.9  Photographs of scientists deploying the CHIRP subbottom profiler in Pamlico Sound, NC. This device provides an image of the layers of sediments beneath the seafloor. (Images by S.J. Culver)

Fig. 2.10  CHIRP subbottom data from Pamlico River, NC showing the layers of sediment that inform us on environmental changes

of thousands of years in response to the growth (i.e., Ice Ages) and retreat of glaciers and ice-sheets on the continents (i.e., glacial-interglacial cycles). It is these sea level changes, and the response of the river systems, that have really shaped the coast here. Large channels within river valleys are buried beneath the sediments of Pamlico and Albemarle Sounds. They show up as U-shaped reflections up to a

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Fig. 2.11  Map showing the river valleys (blue) that were carved in northeastern North Carolina when sea level was 120 meters (400 feet) lower than today during the Last Glacial Maximum approximately 20,000 years ago

mile (1.6 km) wide and 100 feet (30 m) deep (Fig. 2.11). The valleys were carved as the glaciers and ice-sheets expanded across the northern hemisphere, most recently beginning around 75,000 years ago, taking water out of the oceans and causing sea level to fall by roughly 400 feet (120 m). With the lowered sea level, the coast was tens of miles farther east than it is today, and rivers cut downward to create valleys. As the ice-sheets receded, beginning around 20,000 years ago, sea-level rose, and the valleys filled with sediment from the rivers and estuaries. The shape of the present estuaries is inherited from those river valleys, as sea level rose then overtopped the interstream divides (the high areas between valleys). As sea level continues to rise into the future, the Albemarle, Pamlico and Neuse River estuaries (Fig. 2.11) will expand and the shorelines will shift westward. Even more sobering are the layers of older sediment that are seen in the imagery, which show us how far west the coast was around 80,000  years ago (Fig.  2.12). Prior to the last glacial episode, sea-level was higher than today, and the ocean shoreline extended along a prominent feature called the Suffolk Scarp (a.k.a., the Suffolk Shoreline). This ancient shoreline lies 75 miles (120 km) west of the modern ocean shoreline on the Outer Banks. The present land surface and the locations of the various coastal counties and communities (Swanquarter, Belhaven, Oriental,

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Fig. 2.12  Map of northeastern North Carolina and southeastern Virginia showing the elevation of the land, and the location of the Suffolk Shoreline (a.k.a., the Suffolk Scarp). This linear feature marks where the ocean shoreline was between approximately 125,000 and 80,000 years ago

Edenton, etc.) between the Suffolk Shoreline and the modern coast were underwater when this shoreline was active. Sea level was up to 20–25 feet (6–7.5 m) higher than today. Other layers suggest that large areas were once extensive tidal flats; regions dominated by large tides, unlike anything we see here today. This would indicate certain sea-level conditions that favor a much larger tidal range than today, which could greatly modify the coast. This demonstrates the potential for future change under worst case scenarios of catastrophic melting of ice sheets in Greenland and Antarctica. The seismic data provide us with a view of targets beneath the surface that we want to sample to understand the environmental changes and ages. This is done by using a vibracorer again, much like that used on the barrier islands. However, vibracoring in the sounds is a bit more challenging than on the land. First, the vessel (Fig. 2.13) needs to be nearly stationary. This is done by laying out four anchors

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Fig. 2.13  Vibracoring on the Croatan Sound, west of Roanoke Island, NC (see Fig. 2.1) from the stern of the RV Stanley R. Riggs. (Image by S.J. Culver)

from each quarter of the boat; a job that requires a good captain, patience, and strong-armed crew members (students mostly) to take in and lay out anchor line. The vibracorer is prepared without the tripod and is lowered over the stern of the vessel using a winch mounted to a U-frame that extends outward. Divers are used to guide the corer down, take careful measurements, and cap the bottom of the core as it is pulled out of the seabed. The core is brought to the surface (Fig. 2.14) and onto the deck, cut, and returned to the lab and subjected to the same analyses described before. From these, we can confirm times of greater tidal influence, and times when this area was under shallow waters of the inner continental shelf. We can also confirm changes in the estuaries due to variations in the number of inlets through the Outer Banks.

Change Is the Only Constant What have we learned from all of this research effort? Quite a lot actually. We’ve shown that our coast is much more dynamic, subject to a wider spectrum of change on shorter timescales, than we ever imagined. We’ve been living in a period of relative stability over the last 400 years or so, with what are relatively minor changes

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Fig. 2.14  Retrieving a vibracore from Pamlico Sound, NC using the A-frame on the RV Stanley R. Riggs. (Image by S. J. Culver)

occurring to the Outer Banks, until recently. Even these geologically and historically minor changes – shoreline erosion, inlet formation, etc. – currently cost millions of dollars each year in loss of property, maintenance, and business losses. What happens as climate changes, and sea-level rise accelerates, as is occurring now? Our data show that the islands tend to become more fragmented, eroding rapidly, and allowing much more ocean water to enter the estuaries. This has multiple effects, which will greatly impact the various ecosystems and residents throughout the region. As barrier islands become more fragmented, an increase in the tidal range and tidal currents will occur, which will inundate low-lying areas and further exacerbate the effects of sea-level rise. As the estuary expands and deepens, wave energy will increase, which will increase rates of estuarine shoreline erosion and threaten the existence of coastal properties. An increase in the number of inlets, in addition to destroying the roads and properties, will alter sediment transport and trap sand which will increase rates of ocean shoreline erosion. Changes to the salinity and the suspended sediment in the water will affect the living organisms in the region, impacting the various fisheries (fin-fish as well as shell-fish). Rising waters and increasing salinities will result in saltwater intrusion into farmlands, rendering them unproductive for crops, and will contaminate water wells used for drinking water and irrigation. All of these issues directly impact the livelihoods of well over a million people in North Carolina and Virginia. Our modern coastal societies and community structures are intertwined with the coastal environment. We are intimately connected to both the land and the water.

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There are uncertainties we have to deal with. How fast will sea-level rise in the future? At present, in northeastern NC, sea level is rising at about 4 mm (0.15 inches) each year, but it is accelerating. As melting of the Greenland ice sheet continues at ever-increasing rates, and seawater expands as it heats, and with a contribution of changes to ocean circulation patterns, sea level could easily rise by over 3 feet (1 m) by the year 2100. This is a serious consideration for coastal counties, many of which have an average elevation of approximately 2  feet (0.6  m). How will storm frequency and intensity be affected? Hurricanes derive their energy from very warm surface ocean waters. Our data and those of other researchers suggest an increase in hurricane activity during the warm surface ocean conditions of the Medieval Warm Period. However, we are already exceeding the temperatures of that period. Models and historical data suggest a recent increase in the number of intense hurricanes, which will likely continue into the future, but it is not clear whether the total number of hurricanes in a year will increase. What will be the impact on winds and precipitation in the region? This has significant implications for flooding, water for agriculture and people, wave energy and coastal erosion. Recent calculations indicate that winter precipitation in eastern North America has increased as a result of the human influence on climate. How will humans respond and attempt to mitigate the impacts of climate change? This is the most significant question. Will society accept that the current pattern of change is real and will continue and accelerate, and make the difficult political and economic decisions to stave off worst-case scenarios involving several meters of sea-level rise? Or will we take a path of indifference that will commit our children to the most extreme consequences. We understand, based on changes in the past, what we might expect in the future, and we know that we must be prepared to deal with the changes. Acknowledgments  I am forever grateful to the many students, both graduate and undergraduate, who contributed to the knowledge expressed in this paper via their back-breaking work in the field, and tedious hours in the laboratory. Many colleagues also contributed, most notably, Dr. Stephen Culver, Dr. Stanley Riggs, Dr. Eduardo Leorri, Dr. Ryan Mulligan, Dr. Siddhartha Mitra, Dr. John Wehmiller, Dr. Reide Corbett, Dr. J.P.  Walsh, Dr. Ben Horton, Dr. Andy Kemp, Dr. Kathleen Farrell, and Dr. Rob Thieler. Without funds to support this type of work, our knowledge would be very limited. I would like to acknowledge funding from the U.S. Geological Survey, the National Science Foundation, and the Cushman Foundation for Foraminiferal Research.

If You Would Like More Information Culver S, Grand Pre C, Mallinson D, Riggs S et al (2007) Late Holocene Barrier Island Collapse: Outer Banks, North Carolina, U.S.A. Sedim Rec 5:4–8 Donnelly JP, Woodruff JD (2007) Intense hurricane activity over the past 5,000 years controlled by El Niño and the West African monsoon. Nature 447:465–468 Donnelly JP, Hawkes AD, Lane P, MacDonald D et  al (2015) Climate forcing of unprecedented intense-hurricane activity in the last 2000 years. Earth’s Future. https://doi. org/10.1002/2014EF000274

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Fitzgerald DM, Fenster MS, Argow BA, Buynevich IV (2008) Coastal impacts due to sea-level rise. Annu Rev Earth Planet Sci 36:601–647 Kemp AC, Horton BP, Donnelly JP, Mann ME et al (2011) Climate related sea-level variations over the past two millennia. Proc Natl Acad Sci 108:11017–11022 Horton BP, Rahmstorf S, Engelhart SE, Kemp AC (2014) Expert assessment of sea-level rise by AD2100 and AD2300. Quat Sci Rev 84:1–6 Kopp RE, Horton BP, Kemp AC, Tebaldi C (2015) Past and future sea-level rise along the coast of North Carolina, USA. Clim Change. https://doi.org/10.1007/s10584-015-1451-x Mallinson D, Culver S, Leorri E, Mitra S et al (2018) Barrier Island and estuary co-evolution in response to Holocene climate and sea-level change: Pamlico Sound and the Outer Banks Barrier Islands, North Carolina, USA. In: Moore L, Murray B (eds) Barrier dynamics and the impact of climate change on barrier evolution. Springer. https://doi.org/10.1007/978-3-319-68086-6_3 Mallinson DJ, Smith C, Mahan S, Culver S et al (2011) Barrier Island response to Late Holocene climate events, North Carolina, USA. Quat Res 76:46–57 Mallinson DJ, Smith CW, Culver SJ, Riggs SR et al (2010a) Geological characteristics and spatial distribution of paleo-inlet channels beneath the Outer Banks Barrier Islands, North Carolina, USA. Estuar Coast Shelf Sci 88:175–189 Mallinson DJ, Culver SJ, Riggs S, Thieler ER et al (2010b) Regional seismic stratigraphy and controls on the Quaternary evolution of the Cape Hatteras region of the Atlantic passive margin; USA. Mar Geol 268: 16–33 Mallinson D, Riggs S, Culver S, Thieler R et al (2005) Late Neogene and Quaternary evolution of the northern Albemarle Embayment (Mid-Atlantic Continental Margin, USA). Mar Geol 217:97–117 Parham PR, Riggs SR, Culver SJ, Mallinson DJ et al (2013) Quaternary coastal lithosomes, depositional environments, and sequence development in a passive margin setting, northeastern North Carolina and southeastern Virginia. Sedimentology 60:503–547 Riggs SR, Ames DV, Culver SJ, Mallinson DJ et  al (2009) In the eye of a human hurricane: Oregon Inlet, Pea Island, and the northern Outer Banks of North Carolina. In: Kelley JT, Young RS, Pilkey OH (eds) Identifying America’s most vulnerable oceanfront communities: a geological perspective, Geological Society of America, Special Publication. Geological Society of America, Boulder, pp 43–72 Riggs SR, Ames DV, Culver SJ, Mallinson DJ (2011) The battle for North Carolina’s coasts: evolutionary history, present crisis, and vision for the future. University of North Carolina Press, Chapel Hill Thieler ER, Foster DS, Himmelstoss EA, Mallinson DJ (2014) Geologic framework of the northern North Carolina, USA inner continental shelf and its influence on coastal evolution. Mar Geol 348:113–130

Chapter 3

Time and Tide Wait for No Man Andrew C. Kemp and Benjamin P. Horton

I’m just come sittin’ on the dock of the bay Watchin’ the tide roll away I’m sittin’ on the dock of the bay, wastin’ time Looks like nothin’s gonna change Everything seems to stay the same –Otis Redding (1968)

Abstract  Relative sea level is the difference in height between the coast and sea surface. It changes across space and through time in response to many different physical processes operating on a range of scales. Using an example from North Carolina, USA, we introduce some of these key processes and explore how their importance varies on timescales from hours (e.g., hurricanes and tides) to millennia (e.g., ongoing subsidence of the coast). Below the salt marshes of North Carolina (and elsewhere) are sequences of sediment that that accumulated over thousands of years and record relative sea-level changes. Geologists collect this sediment, establish its age and interrogate it to understand when and how relative sea level changed long before people began to make systematic measurements. This research shows that the rate of rise during the twentieth century was without precedent in ~2000 years. Keywords  Salt marsh · Relative sea level · Foraminifera · Isostasy · Outer Banks · North Carolina · Fieldwork A. C. Kemp (*) Department of Earth and Ocean Sciences, Tufts University, Medford, MA, USA e-mail: [email protected] B. P. Horton Asian School of the Environment and Earth Observatory of Singapore, Nanyang Technological University, Singapore, Singapore e-mail: [email protected] © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 S. J. Culver (ed.), Troubled Waters, Springer Climate, https://doi.org/10.1007/978-3-030-52383-1_3

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Did Otis Redding Get It Right? And Why Should We Care? Sitting on a dock, undisturbed by the wider world, and looking out at the bay on a warm and sunny day is a luxury usually only enjoyed during a vacation. If you are fortunate enough to find yourself on vacation in coastal North Carolina, USA (perhaps on the famous Outer Banks barrier islands; Fig. 3.1) and chose to spend a day doing exactly that, you would observe the tide roll in and you would watch it roll away about 6 h later. Over the course of the day sea level would rise with the incoming tide and then fall with the ebbing tide. What comes next is a thought experiment. Instead of enjoying that single day on the dock, what if you could sit there for a

Fig. 3.1  Map of eastern North Carolina, showing locations of places mentioned in text. The Outer Banks barrier islands are cut by several inlets

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month, a year, a decade, a century, or perhaps even a few millennia? How would sea level change on those different timescales along the coast of North Carolina and what physical processes would cause the changes that you observed? And since nobody sat on the dock for the past ~2000 years and there were no instruments making measurements, how do we know that sea-level in North Carolina did change? An important definition must be made before we can proceed any further. The key quantity that we are interested in is relative sea level, which is the height of the sea-surface with respect to the land. In short, it is what the passive observer on the dock in North Carolina would observe and, crucially, it can change because the sea and/or land surface moved up/down as a consequence of many different physical processes. To complicate matters, the sea and land can move in the same direction, opposite directions, or not at all, depending on the time and place where the observations are made. This means that in our example from North Carolina, relative sea-level changes through time and the causes of those changes will depend on what timescale we are interested in (minutes to millennia). Furthermore, it means that relative sea level can (and does) vary across space, such that relative sea-level trends in North Carolina are not always, if ever, the same as those elsewhere (for example, in South Carolina, South Africa, or Singapore). Sea-level rise will be one of most widespread, costly, and difficult to manage effects of the climate changes predicted for the remainder of the twenty-first century and beyond. To accurately predict local sea-level rise (since this, not the global average, is the quantity that matters to the people and organizations tasked with managing our coasts and planning for future changes) requires an understanding of how and why relative sea-level can vary through time and across space. The trajectory of socio-economic impacts caused by sea-level rise will not be an abrupt change from “dry” to “flooded”, but rather a step-wise progression of worsening and more frequent effects. Imagine a building in a coastal community, perhaps a private home or a piece of expensive public infrastructure such as an airport or a power station. It was likely constructed to be above and beyond the reach of floods from the ocean. As relative sea level rises, tides, waves, and storms are carried to higher elevations and further inland. The first impact on our building is likely to be anomalous flooding during a (near) worst-case scenario when large waves during a major storm arrive during a particularly high tide. We might think of how Hurricane Sandy impacted New York City as an example. Continued relative sea-level rise will make such events more common because it ceases to be necessary to have all of the factors align in time and space to cause flooding. As more time goes by even unusually high astronomical tides without waves and storms may begin to flood the building. This phase is sometimes called “sunny day” or “nuisance” flooding and can currently be seen impacting locations such as Annapolis by closing roads on predictable days. Ultimately, our location will be impacted by every tide and, eventually, complete flooding will occur. The amount of time that elapses between these phases depends on the rate of relative sea-level change and the impact will depend on the anticipated lifespan of the building compared to the time frame of relative sea-level rise.

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Short-Term Processes Controlling Relative Sea Level Tides During a single day we already recognized that our observer sitting on the dock witnessed a regularly-paced rise and fall of the sea surface as the tide came in and retreated. On this very short timescale, the land surface is essentially stable and the cause of relative sea-level change is the pull of gravity in the Earth-Moon-Sun system. Over the course of a month (a particularly generous and relaxing vacation perhaps), the careful observer would note that the height of the high and low tides is not the same every day. When the Sun and the Moon are working together the high tides get a little higher while the low tides get a little lower and we say that we are experiencing spring tides. During these few days tidal range (the difference between high and low tides) is large. In contrast, at those times of the month when the Sun and the Moon are working against one another, high tides are a little lower and low tides are a little higher. These neap tides cause a period where tidal range is small. Since the procession of the Earth, the Moon, and the Sun is well known, tides can usually be predicted well in advance with a high degree of confidence. Tides must be accurately predicted to ensure (for example) that ships can enter and leave ports and harbors. In North Carolina, the sea level changes caused by astronomical tides are actually very small. At Oregon Inlet (Fig. 3.1), there is a tide gauge (Fig. 3.2) that automatically measures relative sea level every 6 min (and has done so since 1974). It shows that the difference between and high and low tide is, on average, just 0.36 m (14 inches). In contrast, the Bay of Fundy in Nova Scotia has the biggest tidal range in the world, the inflow and outflow of one billion tonnes of water twice each day results in an astonishingly large tidal range of 16 m (53 feet). This is our first example that relative sea level varies from place to place and through time. Even the most diehard holiday maker is unlikely to want to spend an entire year, or a couple of decades, sitting on the dock, but relative sea level continues to change on these timescales. Just as the tidal ranges were larger or smaller at particular times within a month, so they also vary among different months. For North Carolina, the largest tidal range occurs in January (when Earth is a little closer to the Sun, a position called perihelion) and the smallest in July (when Earth is a little further from the Sun, a position called aphelion). On top of all this, the tides vary in a predictable cycle that lasts 18.6 years.

Winds and Ocean Currents Astronomical tides, however, are not the only cause of relative sea level changes to influence the dock on timescales of hours to decades. Prevailing winds and individual weather systems can push water onto, or away from, the coast causing relative sea-level rise and fall respectively by tens of centimeters. The Wright brothers

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Fig. 3.2  Dr. Matthew Wright stands next to the tide gauge at Oregon Inlet, North Carolina. The staff with height graduations is a piece of equipment used to measure the elevation of samples with respect to the tides. Having a tide gauge at a research site makes this task much easier. (Image by A.C. Kemp)

used these coastal winds to make North Carolina the “first in flight” when they successfully completed a controlled and sustained flight at Kitty Hawk (Fig. 3.1) in 1903. The highest rates of relative sea-level rise over the past ~20 years (~15 mm/ yr) occurred in the tropical western Pacific Ocean because intensification of the prevailing trade winds keeps water piled up even as gravity tries to correct this distortion of the sea surface. If and when those trade winds relax, the water that they currently hold in place will flow away from the western Pacific Ocean and that process would contribute to a relative sea-level fall in that region. North Carolina is no stranger to hurricanes and tropical storms, which can raise coastal relative sea level for a period of several hours to a couple of days by forcing (and then holding) water into the sounds behind the Outer Banks (Fig. 3.1). This specific change in relative sea level is called a storm surge and its impacts on coastal populations and infrastructure are worsened if the surge arrives on top of a high (rather than low) tide and brings large waves. A common misconception is that the low atmospheric pressure of a hurricane allows the sea surface to rise. While this so-called inverse barometer effect does occur, its magnitude is small compared to the effect of water being pushed onto the coast by winds. Two events in 2018 provide illustrative examples of how winds can briefly, but dramatically change sea levels in North Carolina (Fig. 3.3c). In September 2018, Hurricane Florence brought

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a

–0.2

22nd 12:00 23rd 00:00 23rd 12:00 24th 00:00

Day and Time in April 2018 Neap Tides

0.2 0.1 0.0 –0.1 –0.2

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Spring Tides

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devastating flooding to many parts of North Carolina and neighboring states. At Oregon Inlet however, the wind field from Florence pushed enough ocean water away from the coast to cause sea level to be 30 cm (~1 foot) lower than expected before the storm track and wind field moved and sea level rose quickly to be 30 cm higher than expected. This 60 cm swing in sea level took place over approximately 20 h. The highest elevation reached by sea level in 2018 at Oregon Inlet was during Tropical Storm Michael in October when a storm surge of 1.3 m was measured. This is a nice example of how the path and speed of a particular storm, rather than its raw strength, controls the height of a storm surge. It just goes to show that a large storm surges are not limited to the biggest and most powerful hurricanes. One way to predict when a hurricane will hit North Carolina is to ask one of us (Horton) when we are going on summer vacation to the Outer Banks because, over the years, several family vacations (often with some fieldwork thrown in for good measure) were cut short by the need to evacuate a coastline in the path of an incoming hurricane! The strength and/or position of ocean currents also affects relative sea level. The Gulf Stream is a warm and fast-moving current that hugs the U.S. southeastern Atlantic coast as it moves northward until it reaches Cape Hatteras, North Carolina (Fig. 3.1), from where it hangs a sharp right turn into the Atlantic and heads toward northern Europe. The Gulf Stream (in combination with other currents in the North Atlantic Ocean) sustains a gradient in the height of the sea-surface, such that it is lower on the U.S.  Atlantic coast and higher near the center of the ocean (near Bermuda for example). The more powerful the Gulf Stream becomes, the more pronounced this gradient becomes. In contrast, if the Gulf Stream weakens, the gradient is diminished and relative sea-level rise occurs on the U.S. Atlantic coast. Instruments in the ocean and along our coasts that record this effect on timescales of months to a few years. Computer simulations of how the climate of the Atlantic Ocean will likely change during the twenty-first century predict that the Gulf Stream will get weaker and ocean water will slosh on to the U.S. Atlantic coast causing relative sea-level rise.

Long-Term Processes Controlling Relative Sea Level When we thought about why relative sea level varies over time periods of hours to a couple of decades, we could reasonably assume that the land-surface in North Carolina was stable and that the changes in the height of the sea surface were caused by processes (such as tides and winds) which moved water that was already in the ocean from one place to another. Now we need to think longer term and we will see that if our observer stays on the dock for many decades to millennia, these assumptions must be reconsidered. To illustrate this point, let’s return to the tide gauge at Oregon Inlet. During the course of a day (Fig. 3.3a), a month (Fig. 3.3b), or a single year (Fig. 3.3c), the changes in relative sea level follow the expected pattern of rise and fall by tides with the occasional evidence of a storm impacting the coast. If instead we remove this short-term noise (with the caveat that one scientist’s noise is

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another scientist’s data) and look at year-on-year trends there is a clear and systematic relative sea-level rise at an average rate of ~4.4 mm/yr. (1.43 ft. in a century). There are, broadly speaking, three processes that explain this long-term trend: (1) expansion of water already in the ocean as it warms up; (2) additional water being transferred to the ocean as ice on land melts; and (3) downward vertical motion of the land (subsidence). The density of seawater is controlled mainly by temperature with a smaller influence from salinity. Since the oceans absorb heat from the atmosphere, when the atmosphere becomes warmer so will the oceans, which causes relative sea-level rise because the ocean water expands. Indeed, this thermal expansion of existing ocean water has been the main cause of global sea-level rise for the 75–100  years since the start of the Industrial Revolution in the mid-nineteenth century. A mass of water can only be in one place at a time. The hydrological cycle moves water from one reservoir (in a figurative, not literal sense of the word) to another. For example, energy from the Sun arriving on Earth at the ocean surface (as most of it does on our Blue Planet), is put to work evaporating water from the ocean (a reservoir) into the atmosphere (another reservoir). At some point down the line, this water condenses and falls back to the surface as precipitation. Over the course of a year and averaged out over the globe (since precipitation often falls somewhere other than where the water was originally evaporated from), the volume of water in the ocean is about constant. However, if conditions permit, there can be a sustained and pronounced imbalance in the hydrological cycle. If the precipitation falls as snow that doesn’t melt in the summer, then over time ice accumulates into a glacier or ice sheet and the amount of water in the ocean decreases resulting in a sea-level fall. For context, enough water was removed from the global ocean in this fashion between approximately 125,000 and 25,000 years ago that global sea level fell by around 130 m (425 ft). In North America, the Laurentide Ice Sheet covered much of Canada and contained up to 2.65 × 107 km of ice, that was up to 2 miles (3.2 km) thick in some places. This disequilibrium also runs in the opposite direction, when the meltwater from shrinking ice masses on land runs off the landscape and into the ocean, which raises relative sea level. This process happens faster than the ice growth, such that the 130 m of water stored on land as ice returned to the ocean in about 20,000 years. In recent years our glaciers and ice sheets have begun to melt at an accelerating rate and are once again delivering water to the oceans. Between 1992 and 2017, an estimated three trillion tons of ice melted from Antarctica, which is equivalent to almost 1 cm of sea-level rise around the world. Changing the volume and mass of the ocean causes the sea-surface to rise even if the land beneath the dock is stable and our observer on the dock experiences relative sea-level rise on timescales of a few decades or longer. Once we begin to think on century and millennial timescales, our assumptions of a stable land surface rapidly become untenable; the surface on which our dock is built is in motion and able to move up and down. In the case of North Carolina specifically and the U.S. Atlantic coast more widely, a key process driving this relative sea-level change is called glacio-isostatic adjustment (GIA). Over the past few thousand years GIA drove subsidence and therefore relative sea-level rise at the

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dock. The Earth is not a solid sphere, but instead has a structure of layers with different chemical compositions and physical characteristics. We live on a solid layer called the lithosphere or crust, but beneath that is the mantle, which flows and deforms if force is exerted upon it. We can draw an analogy with a waterbed; the crust is the surface that we can lie on and the mantle is the water that fills the bed. When someone gets on one side of the waterbed, the surface sinks, but on the other side a compensatory bulge emerges as the water is displaced. Similarly, when the Laurentide Ice Sheet grew over North America it exerted a force on the crust which displaced material in the mantle beneath and uplifted a bulge around the periphery of the ice sheet. When the person gets off the waterbed, the pattern is reversed by the rush of water back to the disturbed side. Likewise, when the Laurentide Ice Sheet was diminished by melting, the peripheral bulge collapsed (subsided) and retreated back toward the former center of the ice sheet near modern-day Hudson Bay, while the area formerly buried by ice uplifted as mantle material returned. A key difference between the waterbed analogy and real-life Earth is how quickly these responses take to occur. The bed responds almost instantly because the medium is water. In contrast, Earth takes thousands of years to adjust because the medium is mantle material with a very different viscosity (think of decadently filling your waterbed with cold honey instead of water for example!). The key point to recognize is that even thousands of years after the ice is gone, the Earth is still seeking a new equilibrium and GIA is ongoing. The U.S. Atlantic coast lies on the peripheral bulge of the former Laurentide Ice Sheet, which today causes the land to subside and our dock to experience an additional source of relative sea-level rise. In the tide-gauge measurements made at Oregon Inlet (Fig. 3.3), GIA contributes about 1 mm/yr. of the measured relative sea-level rise. Since the process occurs slowly, this rate is likely to have persisted unchanged over the past ~2000 years and will continue at the same rate into the future on human timescales of decades to a couple of centuries. If we examine longer timescales (say 5000 or 10,000 years), GIA does not make a linear contribution to relative sea level, but instead slows down from the past toward the present.

Reconstructing Relative Sea-Level The instrumental record of direct relative sea-level measurements from North Carolina and elsewhere illustrates that profound changes are underway in our oceans, but these are short records. The very longest observational time series of relative sea level began in the 1700s in northwestern Europe (Amsterdam), but most records began much more recently. If we want to provide a context for modern changes and understand why they happened, then we need to know how relative sea-level varied naturally in geologically recent times. Generating such a paleo perspective can enhance our ability to peer into the future and to answer fundamental questions such as what fraction of relative sea-level rise since 1900  AD can be assigned to human activities? And can we anticipate the magnitude and

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consequences of future relative sea-level rise? The answers to these questions lie in exploration of the past and to achieve that we need to generate relative sea-level reconstructions. We need a proxy for sea-level. That is, a physical, biological, or chemical marker of how high relative sea level was in the past that is preserved for thousands of years and stands in for the direct instrumental tide gauges. Fortunately, North Carolina has such a proxy in abundance: salt marshes and the organisms that live on and in them. On low-energy, temperate coasts, salt marshes mark the transition between the terrestrial and marine realms. As a consequence of occupying this unique position, salt marshes exhibit a strong environmental gradient encompassing marine, brackish, and freshwater conditions driven by the frequency and duration of inundation by tidal water. The plants that live on salt marshes are adapted to spending at least some amount of time submerged by, or exposed to, saltwater. Plants that live at lower elevations on the salt marsh must be able to survive relatively long and frequent intervals of submergence. In North Carolina, the plant best suited to this habitat is Spartina alterniflora (smooth cord grass). Plants that live at higher elevations on the salt marsh need only survive relatively short and perhaps infrequent intervals of submergence and this environment in North Carolina is dominated by Juncus roemerianus (black needle rush). Salt-marsh plants in North Carolina (and elsewhere) are therefore a sea-level proxy. As a side note on black needle rush, it is one of the few plants to actively take up silica that it then uses to construct a very pointy tip (hence the name needle). If you visit a North Carolina salt marsh be sure to wear long sleeves and eye protection and be prepared to spend the day getting painfully needled and the evening removing tiny splinters where the silica-rich tips of the needles broke off in your skin. A nice example of just how predictable the relationship between plant species and elevation is on salt marshes comes from Boston. In the late nineteenth and early twentieth centuries, surveyors working in Boston sometimes used a reference level called “marsh datum”, because they recognized that the high salt-marsh zone (as identified by the characteristic plants that live there) in particular had a very predictable and robust relationship to the mean high water tide level and that the marsh itself was a strikingly level plane. At that time Boston had considerably more intact salt marsh than it does today, so it was often more convenient for surveyors to level to a nearby salt marsh rather than running a level line to a known benchmark. Go one step further and examine microscopic (and basically immobile) organisms living on the salt-marsh surface and it becomes clear that they too form distinctive assemblages that live at specific elevations. The most commonly used group of organisms in this role are foraminifera (single-celled organisms with a shell that live in saltwater environments; Fig. 3.4). If relative sea level rises, a salt marsh responds by accumulating sediment on the surface to maintain a constant elevation through time. The best place to reconstruct relative sea level is to find the most boring, flat salt marsh imaginable; one that successfully maintained its elevation with minimal disturbance for hundreds to thousands of years. In this game, “Looks like nothin’s gonna change, Everything seems to stay the same” is exactly the type of place we want to find! But how would you

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Fig. 3.4  Scanning electron microscope image of a common species of salt-marsh foraminifer (Trochammina inflata) collected in North Carolina. Most species of foraminifera that live on salt marshes build a shell from tiny particles of sediment that are attached using an organic cement. The structure and shape of the shell is characteristic of the species that constructed it. The foraminifer lives inside the shell and interacts with the environment through the small opening visible in the image. After the foraminifer dies, the shell is incorporated into the sediment and can be preserved intact for thousands of years. At its widest point, this individual is about 0.3 mm wide. (Image by A.C. Kemp)

find such a place? In short, scientists must explore many salt marshes and that can take time. We might first look at maps and try to interpret the landscape to narrow down our search, but after that we get boots on the ground (or in the mud; Fig. 3.5). At each site we push a hollow tube (a corer) into the salt marsh below our feet and pull up a cylinder of sediment that accumulated through time, with the oldest at the bottom and the youngest at the top (Fig. 3.6). The sediment might be peat that formed when salt marsh plants died but didn’t decay because of the water-logged conditions, or it might be mud that was delivered by the daily tides. In some places you might see a layer of sand, representing a time when a big, high-energy event (e.g., a hurricane) impacted the site and had the energy to erode and redistribute this coarse sediment. For many of us, this laborious and physically-demanding task is actually a highlight of the year. Sure, the sun can be relentless, there are snakes, lunch is usually a soggy sandwich, the black needle rush hurts, and you end up wet and dirty (the longer you try to avoid it, the worse it feels when it inevitably happens), but on the plus side, being outside in such a beautiful and peaceful place in the company of friends with no email is wonderful (Fig. 3.5). Sometimes, this type of fieldwork requires an exercise in logistics and some difficult living conditions. Conducting fieldwork in Alaska’s Aleutian Islands often involves being dropped off by float plane, camping in areas where Kodiak bears roam (Fig. 3.7), and working in a region where the weather can make a dramatic turn for the worse (Fig.  3.8). On the plus side, wild-caught salmon for dinner is often better than what is on the menu at home, especially when hungry after a long

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Fig. 3.5 (a) Professors Matthew Brain (left; Durham University, UK) and Ben Horton (right; Nanyang Technological University, Singapore) enjoying a break from working in the salt marsh. The tall grass behind them is Juncus roemerianus (black needle rush) which is the dominant species on North Carolina salt marshes. In the background the border between salt-marsh grasses and the surrounding forest marks the transition from environments regularly flooded by saltwater and those that are freshwater uplands. (b) Almost as dynamic as the Outer Banks themselves, Professor Stephen Culver (East Carolina University) after a quick change from field wear to office wear to reluctantly return to campus for a faculty meeting. (Images by A.C. Kemp)

day in the field! In 2012, we visited a field site on the White Sea in Russia, a 24-hour train ride north from Moscow (and even then one of us fell asleep at the last minute and we found ourselves in the sidings, fortunately our stop was the last stop!) followed by a long day of driving. We stayed in a village’s small wooden school (Fig. 3.9) and experienced a community where people rely on one another and the dairy offers fresh, warm milk in the morning, cream in the afternoon, and butter in

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Fig. 3.6  A “Russian” type core collected, fittingly, from a salt marsh on the White Sea in northwestern Russia (hilariously, our Russian colleagues call this piece of kit a “Dutch” corer). The unit of grey sediment at the bottom of the core is composed of marine silt and clay that was deposited below sea level. The overlying unit is salt-marsh peat that includes the remains of grasses and plants that used to live at the site. This transition from sub- to inter-tidal environment represents a relative sea-level fall caused by ongoing uplift of the land. (Image by A.C. Kemp)

the evening. Perhaps the biggest challenge was getting our Russian colleague Daria to keep working; summer in Russia is a time of abundance and Daria loved nothing more than downing tools at every opportunity to gather wild mushrooms and blueberries that made for a delicious evening meal. Other times fieldwork can be as simple as visiting your local marsh; having a local project is a great way to get students into the field and engaging with local communities (Fig. 3.10). The goal of fieldwork is to select a specific core (or set of cores) that are representative of the environmental and relative sea-level changes that took place over the past few thousand years. These are then recovered and returned to a research laboratory for analysis that often takes months and even years to complete. The goals of this analysis are straight forward: determine (1) how high relative sea level was and (2) when it was there. As always, the devil is in the detail. To figure out how high relative sea level was we rely on reasoning by analogy. When the core is unwrapped in the lab, it is first cut into 1-cm thick depth increments. Within these sub-samples there are likely to be many hundreds of tiny foraminifera that are identified and counted under a microscope. On salt marshes there are just a handful of species of foraminifera to learn how to identify, and once your eye is trained it is possible to count them quite quickly, but the whole process will require many hours at the microscope (a good opportunity to listen to an audio book). It is not unusual for a project to require tens of thousands of individual foraminifera to be tallied. But what do the foraminifera say about the height of relative sea level? Previously we established that some of the species prefer to live at low elevations and experience more frequent and longer duration submergence than other species

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Fig. 3.7 (a) A chartered float plane used to transport personnel and equipment from Kodiak to Sitkinak Island, Alaska. (b) Field camp on Sitkinak Island: home for a week. Although Kodiak bears live on these islands they are (fortunately) rarely seen. The large yellow tent is called an Arctic Oven and is a very comfortable place to eat and sleep; it even has a small stove. (Image by A.C. Kemp)

that favor higher and drier conditions. Therefore, if we know the ecological preferences of a species, we can infer (either qualitatively or quantitatively) the elevation at which a sample from our core must have formed in the past. To make this inference we need to find the modern (i.e., living) analog for the biological assemblage that is present in the core sample. This is achieved by simply collecting surface sediment (in which foraminifera are living) from salt marshes and measuring the elevation of the salt marsh surface at the same time. How old is the sediment in each of those 1-cm thick sub-samples of core sediment? The primary means to answer this question is to radiocarbon date preserved plant remains. When a plant is alive and photosynthesizing, the carbon that it is made of was in equilibrium with carbon in the atmosphere. But when the plant dies, one type of carbon (the carbon-14 isotope, which is also called radiocarbon because it decays radioactively) begins to disappear through time in a systematic fashion. By measuring how much carbon-14 remains in the sample, the time of its death is established with a high degree of accuracy and precision. Very few labs have the instrumentation needed to make this measurement, so the samples are usually

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Fig. 3.8  The typical “commute”, under threatening skies, from base camp to a coastal field site on Sitkinak, Alaska. These salt marshes record relative sea level changes caused by instantaneous and dramatic changes in the land elevation during repeated great earthquakes. The goal of this research is to determine how often earthquakes occur given the very short period of human observation in the region. (Image by R.W. Briggs)

submitted to an external organization. Often, we supplement the radiocarbon chronology by finding depths in the core that correspond to environmental changes and pollution trends of known age. These trends and events are recorded in down-core profiles of elements such as lead, unusual isotopes such as cesium-137, and pollen from plants that lived in the past. Industrialization began in the middle of the nineteenth century in eastern North America and released a lot of pollution into the atmosphere where it was distributed far and wide by prevailing winds. As the consequences of pumping heavy metals into the atmosphere for ecological and human health became apparent, legislation sought to curb pollution. Go to most salt marshes in the mid-Atlantic and northeastern United States and the history of pollution will be immediately clear in down-­ core (i.e., age) profiles of elements such as lead. Deep in the core, before humans were agents of industrial-scale pollution, lead concentrations are stable and low. At some depth up-core, the concentration of lead begins to rise, and this represents the onset of pollution. It continues to rise to a peak, after which the concentration declines up-core again because the Clean Air Act became law, so lead was removed from gasoline and other industrial emissions were sharply curtailed. In some places even more detail in the history of lead pollution is discernible, including an increase

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Fig. 3.9  The wooden schoolhouse in Russia where we stayed while working on salt marshes around the White Sea. We nicknamed the large dog “Wolfy” and he followed us into the field most days and most nights he forced his way through the front door and tried to climb into one of our sleeping bags. Coauthor Horton wears a red cap. (Image by A.C. Kemp)

in pollution associated with manufacturing during World War One and a subsequent decrease as the economy slowed during the Great Depression, for example. The isotope cesium-137 is produced in nuclear reactors and nuclear weapons. Like the concentration of lead, down-core trends in cesium-137 activity can be traced back to human activities of known ages. Following World War Two, several countries sought to acquire, develop, and build nuclear weapons, which required them to be tested at places like Bikini Atoll in the Pacific Ocean. These tests generated cesium-137 that entered the atmosphere and was distributed by winds around the world and was eventually rained out onto surfaces including salt marshes in eastern North America such as those in North Carolina. The deepest occurrence of cesium-137 is usually taken as evidence for nuclear testing becoming increasingly common in the early 1950s and it peaked it in the early 1960s when above-ground testing of nuclear weapons was banned, and most countries adhered to the new rules. Once the testing went physically underground, the cesium-137 did not enter the atmosphere. As anyone who suffers from hay fever knows, plants produce huge quantities of pollen and those pollen grains have a shape and structure that varies among species (hence we can be allergic to one type, but not others). Pollen is extremely resistant to decay and hard to break down. Therefore, when it settles out on the surface of a

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Fig. 3.10  A Tufts University student and professor (Jack Ridge) collecting a sediment core in a Boston salt marsh for an undergraduate senior thesis project. Some of these marshes are heavily impacted by people; we once hit a buried radiator when coring here that someone had dumped years before. (Image by A.C. Kemp)

salt marsh, it is incorporated into the sediment and can stay there, intact, for many thousands of years. Palynologists can look at a pollen grain using a microscope and determine what species of plant it came from (don’t judge them, after all it is no worse than learning to identify species of foraminifera – and a case in point of how seemingly extravagant, esoteric occupations and fascinations can underpin our knowledge of broader issues with great socio-economic importance). This is another example of reasoning by analogy. The natural landscape of forests that existed in eastern North America in pre-colonial times was disturbed by the arrival of Europeans who set about efficiently altering the landscape to grow crops and raise livestock. This shift is preserved in the pollen record and if you know when a particular location was cleared (for example from historical accounts) then observed changes in down-core pollen can be assigned an age. All the approaches briefly explained above enable us to determine the age of the sediment. When this is coupled with our analysis of the sea-level proxy (e.g., foraminifera), a detailed relative sea-level history is produced because we now know the height of relative sea-level in the past and when it was there.

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 elative Sea-Level Change in North Carolina During the Past R ~2000 Years We spent about 5 years reconstructing relative sea-level changes in North Carolina (Fig. 3.11) that occurred over the past ~2000 years (Fig. 3.3e, f) using the approaches described earlier. Five years is about the time it takes to get a PhD degree with all the fieldwork, lab work, analysis, writing (and rewriting), and following of dead ends (“wastin’ time” in the words of Otis Redding) that are involved. The record is, and can only be, relative sea level, which we already established is the net outcome of all processes acting at our sites over the time period under consideration. However, our reconstructions are based on 1-cm thick slices of sediment and these represent some period of time (typically a couple of decades each) and we therefore say they are naturally “time averaged”. Furthermore, we used foraminifera to establish the height of relative sea level and these organisms don’t respond to very short-lived events such as tides. Together these factors mean that our record has a resolution that is too coarse to preserve relative sea-level changes that occurred on timescales shorter than a few decades. This is clear from the smooth nature of the relative sea-­ level reconstruction compared to what a tide-gauge measures (Fig. 3.3) and means

Fig. 3.11  Coauthor Kemp (left) and Dr. Simon Englehart collecting a core of salt-marsh sediment at Sand Point, North Carolina. The steel pipe is extended in 1-m long sections and is pushed into the sediment by hand. In this case half the core is below the ground and will be pulled back up to retrieve a sample to take back to the lab for analysis. (Image by S.J. Culver)

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that we are only seeing the effects of longer-lived processes such as changing the mass and volume of water in the ocean and the vertical motion of the land. In effect we have managed to install someone on the dock for thousands of years, but they were only inclined to report their observations after first averaging them over decades. At first this might seem disappointing news, the annual tide-gauge data for example provides a rich and detailed history of coastal change, but it is actually a good thing. By smoothing away the high frequency processes, we are left with the relative sea-level changes caused by processes that occurred because of significant changes in conditions in North Carolina and the wider North Atlantic Ocean that will be key drivers of future change. On first appraisal, the North Carolina reconstruction (Fig.  3.3e) seems quite straight forward, relative sea level rose continuously and at a steady rate, with some seemingly subtle changes imposed on top of this long-term trend. The long-term linear trend occurred because of GIA as Earth continued to respond to the most recent deglaciation of North America and therefore the majority of relative sea-level change had nothing to do with climate in the direct sense of the relationship. Since we are confident that we know the rate of GIA, it can be removed from the relative sea-level curve to leave us only with the parts caused by climate-driven processes acting on decadal to centennial timescales (Fig. 3.3f). This so-called “detrended” sea-level record shows some interesting features. There is a period of stability followed by a hump and then a marked rise beginning in the late 1800s. Let us first tackle the recent acceleration because it is the most obvious feature in North Carolina and also shows up time and time again in similar records produced elsewhere. Put simply, this is the onset of modern sea-level rise caused initially by warming of the oceans and more recently by melting of ice. It is this acceleration of global sea-level rise that has scientists and others concerned for the future of our coasts because the rate of rise is predicted to accelerate, resulting in more and more relative sea-level rise unless carbon dioxide emissions are curtailed. The earlier bumps and wiggles are intriguing features, they probably represent periods of time where changes in ocean and atmospheric circulation that were sustained for several hundred years pushed water onto the coast of North Carolina and then allowed it to return to the open ocean.

What Do We Know? Relative sea level is what a passive observer (sitting, for example, on a dock or a similar perch; Fig. 3.12) would observe and is the net outcome of a rich tapestry of physical processes that cause the ocean and/or land surface to move up or down depending on the time and place being considered. On timescales of hours to a few years, the land surface is effectively static and relative sea level changes in response to predictable astronomical tides and the effects of winds and ocean currents. On timescales of a few decades to millennia, there can be large relative sea level changes caused by vertical land motion. In North Carolina the land surface is subsiding

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Fig. 3.12  Coauthor Kemp taking a nap while waiting for a boat to collect the field party at the end of a day working in mangroves along Florida’s intercoastal waterway, much to the confusion of passing pleasure boaters. (Image by S.E. Engelhart)

(relative sea-level rise) because of a process called glacio-isostatic adjustment and, since the late nineteenth century, this trend has been exaggerated as the ocean surface rises because of expansion of existing water as it heats up and by melting of ice, that adds mass to the ocean. We only have direct measurements of relative sea level going back a few decades in most places, but we can use geological methods, approaches, and reasoning to reconstruct how it changed over thousands of years. In North Carolina we develop these reconstructions by collecting cores from salt marshes and using them to establish how high relative sea level was and when it was there. Detailed reconstructions spanning the past ~2000 years show that the high rate of relative sea-level rise in North Carolina and globally during the twentieth century was unprecedented in the context of the ~2000 preceding years. Prior to the twentieth century relative sea-­ level rise occurred almost exclusively because of the land moving downward. As we look ahead, we can expect relative sea-level to rise at ever faster rates in North Carolina as ongoing land subsidence occurs with a rising sea surface. But some of that fate is in our own hands. For example, projections for Wilmington in North Carolina predict a nine in ten chance that relative sea-level rise during the current century will be between 42 cm and 132 cm under a business-as-usual scenario for carbon dioxide emissions, but 24–94 cm under a scenario in which emissions are

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sharply curtailed. That difference might very well be the difference between the dock surviving or being surrendered to the encroaching ocean. Acknowledgments  Funding for reconstructing relative sea-level change in North Carolina came from the National Science Foundation, the National Oceanic and Atmospheric Administration, and the University of Pennsylvania. We would like to thank our wonderful colleagues at East Carolina University (in particular Steve Culver, Dave Mallinson, Stan Riggs, Dorothea Ames, and Reide Corbett) for inviting us to work closely with them to understand the recent geological history of the Outer Banks and for being so welcoming and supportive of us over the past 15 years. We are also grateful to our colleagues who offered their time and hard work during fieldwork campaigns in North Carolina including Andrea Hawkes, Matthew Wright, Candace Grand-Pre, and Simon Engelhart.

If You Would Like More Information Church JA, White NJ (2011) Sea-level rise from the late 19th to the early 21st century. Surv Geophys 32:585–602. https://doi.org/10.1007/s10712-011-9119-1 Clark JA, Farrell WE, Peltier WR (1978) Global changes in postglacial sea level: a numerical calculation. Quat Res 9:265–287 Dawson A (2018) Introducing sea-level change. Dunedin Academic Press, Edinburgh Dutton A, Carlson AE, Long AJ, Milne GA et al (2015) Sea-level rise due to polar ice-sheet mass loss during past warm periods. Science 349:aaa4019. https://doi.org/10.1126/science.aaa4019 Engelhart SE, Horton BP (2012) Holocene sea level database for the Atlantic coast of the United States. Quat Sci Rev 54:12–25. https://doi.org/10.1016/j.quascirev.2011.09.013 Horton BP, Kopp RE, Garner AJ, Ha CC et  al (2018) Mapping sea-level change in time, space, and probability. Annu Rev Environ Resour 43:481–521. https://doi.org/10.1146/ annurev-environ-102017-025826 Kemp AC, Horton BP, Donnelly JP, Mann ME et al (2011) Climate related sea-level variations over the past two millennia. Proc Natl Acad Sci 108:11017–11022 Kopp RE, Kemp AC, Bittermann K, Horton BP et al (2016) Temperature-driven global sea-level variability in the Common Era. Proc Natl Acad Sci:201517056. https://doi.org/10.1073/ pnas.1517056113 Lambeck K, Rouby H, Purcell A, Sun Y et al (2014) Sea level and global ice volumes from the Last Glacial Maximum to the Holocene. Proc Natl Acad Sci 11:15296–15303 Milne GA, Gehrels WR, Hughes CW, Tamisiea ME (2009) Identifying the causes of sea-level change. Nat Geosci 2:471–478. https://doi.org/10.1038/ngeo544 Pirazzoli PA (1991) World atlas of Holocene sea-level changes, Elsevier oceanography series, vol 58. Elsevier, Amsterdam, pp 1–299 Shennan I, Long AJ, Horton BP (2015) Handbook of sea-level research. Wiley, Chichester

Chapter 4

Barrier Island Breakdown: The Ephemeral Outer Banks of North Carolina Stephen J. Culver

Abstract  This chapter describes sudden coastal change that took place in North Carolina, USA 1200  years ago during a period of warmth in the northern hemisphere known as the Medieval Climate Anomaly. It explains how we know that this event occurred, and it describes the geologic tools that we used to reconstruct the event. A large segment of the Outer Banks barrier islands was flattened, probably by one or more strong hurricanes. Oceanic waters entered estuarine Pamlico Sound, which metamorphosed into an open Pamlico Bay. The tidal range increased, tidal currents increased in strength, salinity increased, and fish migrated as they adapted to new conditions. Human inhabitants of the region would also have had no choice but to adapt. Over 500 years the barrier islands were reconstructed and pre-storm conditions returned by the time the first Europeans landed on this coast in 1585. A similar series of events could occur once more in coastal North Carolina during the current period of global warming. Economic effects would be disastrous. Keywords  North Carolina · Outer Banks · Pamlico Sound · Medieval Climate Anomaly · Hurricanes · Sea-level rise · Foraminifera · Barrier island segmentation

A Big Event Something happened in coastal North Carolina, USA 1200 years ago. The southern part of the Outer Banks barrier islands, which had formed several thousand years earlier, were, for want of a better word, decimated. Large portions of this almost continuous chain of barrier islands that juts out into the Atlantic Ocean (see chapter by Mallinson) disappeared. The sand that formed the islands was smeared out and

S. J. Culver (*) Department of Geological Sciences, East Carolina University, Greenville, NC, USA e-mail: [email protected] © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 S. J. Culver (ed.), Troubled Waters, Springer Climate, https://doi.org/10.1007/978-3-030-52383-1_4

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much was transported westwards into Pamlico Sound. Oceanic waters entered Pamlico Sound through these gaps. Indeed, one gap, where Ocracoke Island is currently located, was so large that it transformed the shallow body of water, Pamlico Sound, normally protected from the high energy Atlantic Ocean by the nearly continuous Outer Banks, into an unprotected Pamlico Bay, that was directly connected to the open ocean. Not only were sediments redistributed, modeling by my colleagues shows that currents adjacent to the breaks in the islands became stronger, the tidal range within the Bay doubled in places, and the salinity of the Bay also increased. All of these changes affected the organisms within the Bay. Native Americans who utilized the resources of this complex coastal system would have adapted to the new circumstances as did the fish, clams, snails, crustaceans, worms and smaller organisms, most probably by migrating, if they could do so. The range of salt-water fish expanded further westward. As salty waters extended further upstream, species of brackish water fish migrated up the Neuse and Tar-Pamlico estuaries. Native Americans surely followed them with their nets. What event caused these drastic changes? Was it a sudden process or was it gradual? Had it happened before and could it happen again? How do we know that this environmental perturbation occurred? What are the various lines of evidence that allow us to understand this, from a geological perspective, very rapid episode of change? Why should we be interested in this event? What is its relevance to us today? I’ll try to explain.

Three Hurricanes I arrived at East Carolina University (ECU) in August 1999. I was the new Chair of the Department of Geology (now named the Department of Geological Sciences). In an interesting parallel, I had migrated from the Natural History Museum in London to ECU because of a change in circumstances, akin to the migration of the fish and clams noted above (although, of course, I did not think of it in those terms at that time). I spent a year or so getting used to my new administrative tasks and then I turned my attention to another item in my job description, research. But three events occurred within several weeks at the beginning of my first year at ECU. The low-lying land of eastern North Carolina was hit in quick succession by three hurricanes, Dennis, Floyd and Irene. The result was terrible floods that affected the region for several years (Figs. 4.1 and 4.2). We’ve had enough hurricane hits along the Gulf and Atlantic coasts of the US over the past decade or so to know that some hurricanes are mainly rain events (such as Floyd), some are wind events, and some are storm surge events. Some terrible storms combine all three characteristics to horrifying effect. The Floyd floods affected me personally – my wife, my two children and cat, newly arrived from the UK, had to inhabit a hotel room for five months, living out of our suitcases until we

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Fig. 4.1  Reconstruction of NC Highway 33 on the eastern edge of Greenville, North Carolina. One of hundreds of cases of road/bridge destruction in eastern NC at locations where roads crossed rivers or creeks during flooding caused by Hurricane Floyd in September 1999. (Image by S.R. Riggs)

Fig. 4.2  Highway 33 (10th Street) in Greenville, NC during Hurricane Floyd flooding in September 1999. An East Carolina University building is at the right edge of the picture. (Image by S.R. Riggs)

bought a house (carefully selected for its elevation) and we could get our belongings, shipped from England, out of storage. But the three hurricanes and their impacts must have registered subliminally in my brain, ready to influence my future research when the time was right.

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The Genesis and Evolution of a Research Project I began to explore research possibilities during my second year at ECU.  I am a micropaleontologist by training. I study tiny fossils, small enough to need a microscope to view them closely enough to understand their morphology and to identify them (Fig. 4.3). The organisms are called foraminifera (“forams” for short). They are single-celled and distantly related to the amoebas that we all heard about at school. One of the main differences is that they have a shell composed of secreted calcium carbonate, or of sand and silt grains that the organism collects from their immediate environment and cements together. Forams live in all marine environments from estuaries and coastal marshes to the deepest trenches under the oceans that cover most of our planet. Most species live on or just under the sea floor (benthic) but some float near to the surface of the oceans (planktonic). Their shells are incredibly abundant. I once travelled to the bottom of the Atlantic Ocean off the coast of New Jersey, USA in the DSRV Alvin, the famous submarine that found the Titanic and the amazing black smokers, with their associated weird and wonderful animal communities, at sea-floor spreading centers beneath several oceans. During my dives I collected samples of sediment from the sea floor using the articulated arms at the bow of the Alvin. On return to the lab I washed the samples over a sieve Fig. 4.3  The morphological diversity of foraminifera. (Image by M.A. Buzas)

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to remove the mud. All I had left was sand. But that was my goal – the sand-sized particles were not grains of quartz such as those that comprise the beach sands of the Outer Banks and the wind-swept dunes behind them. Almost every single grain was a foram shell. In a handful of that sand were tens of thousands and perhaps hundreds of thousands of individual shells. Imagine how many such shells there are at the bottom of the oceans! Another way to understand their abundance is to consider the fact that the pyramids of Egypt are built of limestone blocks that consist entirely of foram shells cemented together! You might wonder why anyone would study such seemingly esoteric organisms as foraminifera. It is because they are very useful for finding energy resources. In fact, I’ve heard it said that there are more micropaleontologists in the world than all the other various kinds of paleontologists added together. That may or may not be true, but it explains why we micropaleontologists are not particularly rare or unusual beings. Because forams are so abundant, live in all marine environments, and have fossilizable shells, they are useful for exploring for oil and gas. When a test-well is drilled, the ground-up rock particles, that are returned to the surface within a constant stream of mud, often contain undamaged fossil foram shells. An experienced micropaleontologist can evaluate the shells, identify them and determine the environment in which the sediments containing them were deposited. We are able to do that by studying the environmental distribution of modern foram species (Fig. 4.4) and applying the Principle of Uniformitarianism, “The Present is the Key to the Past”, explained briefly in the Introduction to this book. Because

Fig. 4.4  Graduate student, Ray Tichenor, left, sampling sediment containing living foraminifera in Pamlico Sound, North Carolina. Research colleague, Andy Kemp (right) is helping to survey in the elevation of the sample site. (Image by S.J. Culver)

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forams, like all groups of organisms, evolve through time while some species become extinct (and both of these processes are irreversible), the micropaleontologist can also tell the relative age of foram-containing strata. With these two lines of information (paleoenvironment and age), combined with others such as sedimentological, geochemical and geophysical data, the three-dimensional structure of sedimentary rock basins can be reconstructed and the locations where a petroleum company might drill for oil and/or gas can be narrowed down to much smaller target areas. My specialty in micropaleontology is the reconstruction of past environments using benthic foraminifera. Back in 2001 when I was redirecting my research activities, I discussed the geology of coastal North Carolina with my colleagues Stan Riggs, Dave Mallinson and Reide Corbett and we came up with several research topics that would contribute to a much larger research program, involving the North Carolina Geological Survey and the U. S. Geological Survey, who funded the program. The aims of the program were to understand the origin and evolution of North Carolina’s coastal system, to understand the modern geological and oceanographic processes that occur today, and to determine what these two threads of information might mean for the future of this large and very complex system. This research would build on the geologic information preserved in a suite of 30 or more vibracores collected several years earlier in Pamlico Sound by Riggs. A vibracorer vibrates a section of aluminum irrigation pipe into sandy or muddy sediments, on land or under shallow water (see Mallinson’s, Leorri’s and Farrell’s chapters), to collect a core of those sediments (Figs. 4.5 and 4.6). The core of sediment within the pipe can be as long as 8 m (26 ft). The Riggs cores were placed in storage until someone came along to study them. That happened to be me. The cores were cut and split lengthwise (Fig. 4.7) and Riggs had drawn graphic descriptions (called “logs” like a sea captain’s or Captain Kirk’s logs) of the sediments in each of the forty or so cores. My research goal was to reconstruct the last several Fig. 4.5 Vibracoring adjacent to the Outer Banks barrier islands in Pamlico Sound, North Carolina. The author is climbing the tripod to deploy the core pipe. (Image by J. Watson)

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Fig. 4.6  Vibracoring from the R/V Stanley R. Riggs in central Pamlico Sound, North Carolina. (Image by Geological Sciences, ECU staff)

Fig. 4.7  Research team members logging and sampling a core of sediment from an Outer Banks, NC barrier Island. (Image by North Carolina Geological Survey staff)

thousand years of paleoenvironmental change in Pamlico Sound by studying the forams in several of these cores. But which core should I choose to commence the project? I pored over the logs and one core jumped out at me. Most of the longer cores were composed of mud (mud is easier to penetrate than sand and so the longer cores were muddy) but this particular core (PS03) had two distinctive sandy layers interbedded in the mud (Fig. 4.8). I knew from first geological principles that coarser sediments indicate a higher energy environment than finer sediments. Thus, the transition from mud to sand and back to mud again represents a change from a low energy environment to a higher energy environment back to a low energy environment. Ok, so this core exhibited environmental change and that was what I was looking for. I then spent several days carefully cutting this 8 m core into 2 cm slices. My job was to look at the forams in each of these 400 samples.

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Fig. 4.8  A graphic log by K.M. Farrell, of Pamlico Sound core PS03, paleoenvironmental interpretations, and a visual representation of changing foraminiferal species (biofacies) and, hence, environments in the core. Blue indicates the presence of open marine foraminifera, green indicates high salinity estuary foraminifera and yellow indicates low salinity estuary foraminifera. Rapidly (based on the radiocarbon age estimates) alternating colors show that boundaries between these three biofacies are not sharp because the sediments have been disturbed by burrowing organisms and/or currents which transport some of the tiny foraminiferal shells up and down the core. (Figure by D.J. Mallinson)

The samples sat in my lab for weeks. I was distracted by administrative tasks and, I must admit, was somewhat intimidated by the thought of processing and analyzing 400 samples! But then, a stroke of luck. A student came to me wishing to change her Master’s thesis project. I explained what I had in mind for core PS03 and she committed to the project. And she did an excellent job that resulted in the award of a Master’s degree a year or so later. In addition, Dr. Kathleen Farrell at the NC Geological Survey relogged the core in great detail. But what did these data mean? One core can tell a story, but it is much better to have several. We had more than that in the work of several additional students who cored the sediments of Pamlico Sound. Another three students documented the distribution of modern foraminifera in the coastal waters of North Carolina (Albemarle, Pamlico and Core sounds) and their data served as the model by which the down-core foraminiferal assemblages could be interpreted. So, we had a huge database and it was my job as the organizer

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and “big picture” guy to put all of this together. I did this in a short paper, coauthored by a cast of thousands, which caused considerable interest. It was titled, “Late Holocene barrier island collapse: Outer Banks, North Carolina, USA”. The president for the Society of Sedimentary Geology (SEPM) used this paper as an example of how this kind of research can aid in petroleum exploration. My student senior authored a more detailed research paper a few years later.

Unexpected Results Lead to Thought-Provoking Conclusions What was the evidence for this barrier island destruction? The mud in core PS03 (Fig. 4.8) contained low diversity (ten or fewer species) estuarine, variably brackish, foram assemblages identical to those that live in Pamlico Sound today (Fig. 4.4). That certainly seemed understandable. But the foram assemblages in the two sand layers were very surprising. Specimens were very well preserved and clearly in place because juvenile through to adult specimens were all present (Fig.  4.9). Specimens transported from another location are usually size-sorted and these were not. There were about twice as many species per sample than in the mud assemblages. Several of these species had only been recorded previously on the continental shelf

Fig. 4.9  Many of one thousand specimens of the benthic foram Elphidium excavatum exhibiting excellent preservation and a wide range of specimen size that indicate a lack of sorting by currents. Thus, the specimens can be interpreted as being in situ. The image is of approximately 4000 year-­ old specimens from 515 cm to 520 cm depth in Pamlico Sound core PS03 (see Fig. 4.8). Note red scale bar. (Image by W. Spivey)

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under oceanic salinity conditions. What were they doing in estuarine sediments? Just as surprising was the presence of pristine specimens of several planktonic foraminiferal species that we know are restricted to the warm waters of the Gulf Stream. How do we get shelf benthic species to live behind the barrier islands and well-­ preserved specimens of Gulf Stream planktonic in a core from a modern estuary? The only way this can occur is by removing large portions of the barrier island – the collapse, destruction or segmentation noted above (Fig. 4.10), which permits oceanic waters move onshore. How are large portions of the barrier islands removed? The only way this can occur is by a hit from a tsunami or from a storm or series of storms. We discounted tsunami mainly because we knew that hurricanes regularly impact the Outer Banks and we knew their effects, but we have no record of tsunami (yet). Furthermore, the tsunami explanation seemed less parsimonious than storm impacts. Scientists usually chose the simplest explanation when there are alternatives. This is called the principle of Occam’s Razor, attributed to a Franciscan friar

Fig. 4.10  Reconstruction of Outer Banks, North Carolina, barrier island segmentation 1200 years ago. (Figure by D.J. Mallinson)

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in fourteenth century England. There are slightly varying definitions but, basically, if there are several competing theories that make exactly the same predictions, the simplest one is the better. So, storms were more likely the perpetrators and the barrier islands the victims. Several strong hurricanes have hit the Outer Banks over the past century and caused overwash and the opening of, usually, ephemeral inlets. These inlets do not allow for the colonization of Pamlico Sound by benthic forams from the shelf. We need an event or events of much greater magnitude that destroy large segments of barrier island and allow eddies of Gulf Stream waters to be advected into the Sound by southerly prevailing winds (Fig. 4.10). My mind, for some reason, returned to my family’s miserable experience of five months trapped in a hotel room due to a set of three hurricanes in just several weeks that physically cut off Greenville from the rest of civilization and delayed our purchase of a house. Perhaps a series of very powerful hurricanes traveled up the Gulf Stream a thousand or so years ago and impacted the Outer Banks but, as our data suggest, the southern portion in particular. These must have been extremely powerful storms because their effects were long-lasting. We radiocarbon dated the base of the suspect sand unit using 1000 specimens of a single species of the benthic foram, Elphidium excavatum, that were clearly in situ because specimens ranged from tiny juveniles to full-grown adults (Fig. 4.9). Thus, no transport, sorting and redeposition of shells had occurred. The estimated age was approximately 1200 years before present. The top of the sand unit and, hence, the return to the deposition of mud in a sound protected from the ocean by reformed Outer Banks barrier islands, had an age of approximately 500 years before present. Thus, the segmentation of the barrier islands lasted some 700 years. When the first European visitors arrived in 1585 the map produced by John White showed that the Outer Banks had many more inlets than exist today (see Mallinson’s chapter). The barriers islands had healed somewhat, but evidence of segmentation persisted in these several inlets. Why would such strong and devastating hurricanes occur 1200 years ago? This was the time of the Medieval Climate Anomaly, a period of time lasting a few hundred years when temperatures in the northern hemisphere were warmer than in preceding and succeeding years (the Medieval Climate Anomaly was followed by the Little Ice Age). Warmer temperatures may not necessarily lead to more hurricanes, but the work of several hurricane researchers suggests that warming can lead to more intense hurricanes. That may well be what happened 1200 years ago. The same scenario is relevant today. Mainly due to anthropogenic activities (the burning of fossil fuels, for example) we are currently in a period of global warming of a magnitude (so far) similar to the Medieval Climate Anomaly. The difference is that the warming is happening much faster than 1200 years ago. Furthermore, as described elsewhere in this book, (see the Kemp and Horton chapter) sea-level is rising along the mid-Atlantic coast of the US faster than to the north or south due to subsidence of the land. Current warming climate could well result in more hurricanes and, scarily, perhaps more intense hurricanes. Add perhaps 1 meter (3 ft. 3 in)

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of sea-level rise (by the year 2100) to the storm surge that these hurricanes will bring, and it is not hard to imagine barrier island segmentation happening again. Of course, the effects of segmentation, were it to occur again, would be disastrous at many levels. Natural disasters are only disasters because humans get in the way of natural processes. The barrier island segmentation 1200 years ago probably affected tens (perhaps hundreds) of people. Nowadays, at the individual level, many residents would lose their homes and their livelihoods. At the state level, North Carolina’s coastal tourist industry would be severely impacted. Anything that affects a state’s economy does, of course, have national consequences. Think, for example, of the cost to US of Hurricanes Katrina and Sandy and the several hurricanes of 2017 and 2018 that affected the US Gulf and Atlantic coasts and coastal plains.

The Future What can we do about a barrier island segmentation that might happen a year from now or perhaps a hundred years from now? We cannot stop hurricanes impacting us, but we can plan for adaptation to whatever new circumstances come our way. Adaptation is what our species does best and has been doing since it first evolved in Africa some 300,000 years ago. Opportunity can be the outcome of adversity. In a little book (‘The Battle for North Carolina’s Coast”) published in 2011, the authors (Riggs, Ames, Culver and Mallinson) suggested what some of these opportunities might be in eastern North Carolina. The undeveloped islands would be “A String of Pearls”, the developed barriers would be “Islands of Opportunity” and the low-lying “Land of Water” of the Inner Banks (the marshy mainland coast of Pamlico Sound) could be utilized in new and imaginative ways. A decade later, we are telling the same story. We must accept the reality of coastal change and accept it as part of much broader climate change related to global warming. We must accept the huge amounts of data that show human activities have contributed and continue to contribute to this warming. We must do our utmost to cut back on carbon emissions and slow down the rate of global warming. Certain quotes or snippets of quotes sometimes stick in our minds. For me it is Churchill’s “Never give in, never give in, never, never, never…”, Einstein’s “If we knew what we were doing, it would not be called research, would it?”, Kennedy’s “Ask not what your country can do for you…”, and Saturday Night Live’s “More cowbell.” The pertinent quote in this case of global warming and the associated effects on our coasts, is Gandhi’s “…court of conscience” that “…supersedes all other courts”. We are all on trial in this court for the climate change and sea-level rise for which we are the major causative agent. Will we change our behavior for the sake of our children and grandchildren? Something happened in beautiful coastal North Carolina (Fig. 4.11) 1200 years ago. Let us be ready for when it happens again.

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Fig. 4.11  Sunset over Run Hill, Outer Banks, North Carolina. (Image by S.J. Culver) Acknowledgements  Thanks are due to former ECU graduate students, P.R. Parham, C.G. Smith. D.J.  Vance, I.  Abbene, J.  Ricardo, C.  Grand Pre, J.  Rosenberger, D.  Twamley, C.W.  Smith, J.A. Foley, C.L.T. Stanton, M. Hale, R. Pruitt, L. Metger, K. Peek, K. Best, K. Moran, C.F. Smith, A.  Dietsche, J.  Kegel, and N.  Zaremba. I also acknowledge the US Geologic Survey, National Science Foundation and the North Carolina Geological Survey for supporting our research. Acknowledgement is also made to the donors of the American Chemical Society (Petroleum Research Fund) for partial support of our coastal research in North Carolina.

If You Would Like More Information Culver SJ, Grand Pre CA, Mallinson DJ, Riggs SR et al (2007) Late Holocene barrier island collapse: Outer Banks, North Carolina, USA. Sedim Res 5:4–8 Grand Pre C, Culver SJ, Corbett DR, Farrell KM et  al (2011) Rapid Holocene coastal change revealed by high resolution micropaleontological analysis, Pamlico Sound, North Carolina, U.S.A. Quat Res 76:319–334 IPCC (2018) Summary for Policymakers. In: Masson-Delmotte V, Zhai P, Portner HO, Roberts D et al (eds) Global warming of 1.5°C. An IPCC special report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. World Meteorological Organization, Geneva

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Mallinson DJ, Culver SJ, Leorri E, Mitra S et al (2018) Barrier island and estuary co-evolution in response to Holocene climate and sea-level change. In: Moore LJ, Murray AB (eds) The response of Barrier Islands and barrier spits to climate change. Springer, New York, pp 91–120 Zaremba N, Mallinson DJ, Leorri E, Culver SJ et al (2016) Controls on the stratigraphic record and paleoenvironmental change within a Holocene estuarine system: Pamlico Sound, North Carolina, USA. Mar Geol 379:109–123

Chapter 5

A Different Kind of Sea-Level Story from Malaysia Peter R. Parham

How foolish to believe we are more powerful than the sea or the sky. Ruta Sepetys

Abstract  In many countries of Southeast Asia, the sea is the primary source of food and center of the community. Life is very simple and intertwined with the ocean’s moods. So many people depend on this sea, day after day, generation after generation, despite monsoons, typhoons, erosion and flooding, death and hardship. Surprisingly, little study had been undertaken to help these communities anticipate the impact of coastal change on their lives and livelihoods. My study of nearly every Malaysian island, shore and coastal plain stream allowed me to interpret past coastal influences and predict future impact. It also allowed me to experience this amazing country and her people under every conceivable circumstance, some warm or amusing, some perilous and some death-defying. Keywords  Malaysia · Borneo · South China Sea · Coastal geomorphology · Paleo-sea level

P. R. Parham (*) US Army Corps of Engineers, Conchas, NM, USA Permanent International Fellow, Centre of Tropical Geoengineering, Universiti Teknologi Malaysia, Johor Bahru, Johor, Malaysia © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 S. J. Culver (ed.), Troubled Waters, Springer Climate, https://doi.org/10.1007/978-3-030-52383-1_5

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An Introduction to Sea-Level Change in Malaysia Sea level is changing and affecting coastal zones around the world. This, however, is not the first time it has happened. The last approximately 2 million years of Earth’s history, the Quaternary Period, is defined by expanding and contracting polar ice sheets and corresponding low and high sea levels. The last major glacial interval was at its maximum about 20,000 years ago. Since then, the polar continental ice sheets have been melting causing sea level to rise and flood continental shelves around the world. What were once inland hills became islands. Some islands and low-lying land connections between islands became submerged. Shorelines evolved and backstepped as seas rose ~120 m to modern levels. Since all of the Earth’s oceanic basins are connected, one would think that the melting ice would cause sea level to rise everywhere. Indeed, the land is sinking in some places causing a greater rate of sea-level rise, but at other locations, the land is rising, sometimes faster than the rate of rise caused by the addition of water to oceanic basins. The result is that sea-level changes, in relation to the land, are variable around the world. The country of Malaysia is composed of two parts (Fig. 5.1). Peninsular Malaysia is a contiguous part of the Asian continent and occupies the southern end of a peninsula extending south from Thailand and Myanmar. The peninsula is bounded on the west by the Straits of Malacca and on the east by the southern South China Sea. The other part of Malaysia lies over 600 km to the east, across the South China Sea on the northwestern side of the island of Borneo. The South China Sea separating Peninsular Malaysia from Borneo is shallow, with an average water depth of ~70 m. This submerged area is known as the Sunda Shelf (Fig. 5.1) and is the second largest continental shelf in the world. The waters of the Straits of Malacca are even shallower than those of the southern South China Sea. Around 20,000 years ago, when polar glaciation was at its maximum and global sea level was ~120 m lower than it is now, the Straits of Malacca and the Sunda Shelf part of the South China Sea were dry land. Thus, the islands of Sumatra, Java and Borneo were connected by land to the Asian continent. The connection had a profound influence on the terrestrial biology of the region. Subsequently, as high latitude continental ice sheets melted, seas rose rapidly until 8000–7000 years ago, inundating the Straits of Malacca and the Sunda Shelf. Sea level in this region then rose at a much slower rate for at least 1000 more years to ~3 m above current sea level, after which it fell to the present level. It is this period, between approximately 8000 years ago and present, that most influenced the character of the Malaysia coastal zone as we see it today. The main phenomenon responsible for this higher-than-present mid-Holocene sea level (the Holocene encompasses the last 11,700 years) was a process called continental levering, the vertical movement of land in response to weight added by increased seawater on the continental shelf. Parts of the world far from the direct influence of

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Fig. 5.1  Map of the Southeast Asia region shows the locations of Peninsular Malaysia, Malaysian Borneo, Sunda Shelf and areas of major tectonic activity adjacent to the relatively tectonically stable southern extension of Asian continental crust called Sundaland (outlined with white dashed line). (Basemap from https://www.maps.ngdc.noaa.gov; modified and labelled by the author)

continental glaciers, and which are thought to be relatively tectonically stable, show similar Holocene sea-level records as a result of this process. Another substantial influence on the physiography of much of Malaysia’s coastal zone is its situation on relatively tectonically stable continental crust. Peninsular Malaysia (Fig. 5.2) has been widely considered to be a tectonically stable far-field (far from polar ice sheets) region. This relatively tectonically stable area, known as the Sundaland (it is centered on the Sunda Shelf), contrasts markedly with the zones of intense tectonic activity that surround it, for example, along the west coast of Sumatra (Fig. 5.1) where the 2004 earthquake caused horrific tsunami-related damage and loss of life (see the chapter by Hawkes). A tectonically stable far-field region is an advantageous place to study sea level because the coastal zone is considered to be neither going up nor down, except in response to continental levering. This makes global changes in sea level easier to decipher, while in tectonically active areas, vertical movement of the land can substantially complicate our ability to unravel the global sea-level record. The Malaysian Borneo states of Sarawak and Sabah, particularly Sabah (Fig. 5.3), are tectonically active, resulting in a very different sea-level story from that of the peninsula.

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Fig. 5.2  Map of Peninsular Malaysia shows the areas surveyed by the author (outlined in yellow). (Basemap from https://www.maps.ngdc.noaa.gov; modified and labelled by the author)

The history of sea-level change in Malaysia is different from that of the eastern United States (see the chapter by Kemp and Horton). There are two main reasons for this that operate over different time scales. As polar continental glaciers melted over the last 20,000 years, sea level in both areas rose ~120 m, flooding the continental shelves that were once land. In eastern US, this sea-level rise continues today. In Malaysia, sea level rose to a maximum of ~3 m above present by 6000 years ago then fell to the modern level, constructing a regressive coastal plain. Sea level is now rising again slowly in this region. Because of its relative tectonic stability, the eastern US has experienced multiple, alternating periods of high and low sea level for over two million years. These periods of high sea level were global in scale. In the southeastern US, they produced a broad coastal plain characterized by terraces (see the chapter by Farrell) that step down in elevation and decrease in age towards the coast. In Peninsular Malaysia, also considered relatively tectonically stable over the last two million years, the surficial deposits of the coastal plain consist solely of sediment associated with the

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Fig. 5.3  Map of northern Borneo Island including Malaysian Borneo (Sarawak and Sabah) shows the areas surveyed by the author (outlined in yellow). (Basemap from https://www.maps.ngdc. noaa.gov; modified and labelled by the author)

Holocene (i.e., the last) rise and fall of sea level. There is no evidence on land of any earlier period of higher sea level except in old (>70 million years) deformed strata. The implication is that the much of the Malaysian Peninsula region has undergone slow subsidence for millions of years.

A Needle in a Haystack My research over many years has focused on sea-level change and the coastal zone in both the US and SE Asia. I’ve located, measured and evaluated evidence of past sea-level highstands in many types of coastal environments. This is usually in the form of fossils or other geological clues (e.g., elevated coastal plain terraces and marine deposits) left behind. You can’t always know where these clues will be found. You must go out and search, which can sometimes be hazardous under the best of conditions. Finding them in Malaysia adds an extra level of risk since parts of this country are jungle and there are many islands that are difficult to access (Fig. 5.4). The evidence of former sea levels could be on cliffs or inside caves and crevices (Figs. 5.5 and 5.6). But huge pythons, venomous cobras, and tigers inhabit these areas. Excavations and mining can unearth clues (Fig.  5.7). They could be down wells (Fig. 5.8) or in old graveyards, or on the banks of crocodile-infested rivers.

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Fig. 5.4  The author preparing to get out on the rocks at Tioman Island off SE Peninsular Malaysia. (Image by Mary Ann Parham)

Fig. 5.5  The author collecting fossil oysters attached to a limestone cliff, Langkawi Archipelago, NW Peninsular Malaysia. Fossil oysters are attached to the rock in the crevice to the author’s left. Living rock-encrusting oysters occur near the water level (bottom left of the image). (Image by boatman Biden)

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Fig. 5.6  The author collecting fossil rock-­ encrusting oysters in a partially flooded limestone cave in the Langkawi Archipelago. Chiang Ong holds the ladder. (Image by Timothy Shaw)

These sea-level clues are hard to find but it’s never boring searching for them! Along the way I meet interested people, eager to help or to share their knowledge of their part of the planet. This is always a help, with the possible exception of the time I met a group of Malay teenagers in an oil palm plantation. After explaining, in broken Malay, that I was looking for places where old fossil shells could be found, a caravan of them excitedly hopped on their motor scooters to escort me to the special shell place they knew. Imagine my surprise when we pulled up at a Shell Petrol station! It may have been the wrong outcome, but it’s typical of the willingness of Malaysian people to help in any way.

A New Horizon So, how did I wind up in Malaysia in the first place? I was assisting NOAA with shoreline recovery efforts along the US Gulf Coast following the 2010 Deepwater-­ Horizon oil spill when Steve Culver, Chair of East Carolina University’s Department

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Fig. 5.7  Discussions with Universiti Malaysia Terengganu (UMT) graduate students at a Holocene fossil coral reef and associated shelly deposits excavated from a drainage ditch in an oil palm plantation, NE Peninsular Malaysia. From left to right: Noor Azariyah Mohtar, Noraisyah Sapon, the author, and Rokiah Suriadi. (Image by Emily Parham)

Fig. 5.8  UMT colleague, Jarina, climbing down an old well on Pulau Kapas, Terengganu to sample fossil coral at bottom. The bamboo ladder was made on the spot by the caretaker of the property. (Image by Peter R. Parham)

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of Geological Sciences, mentioned a potential opportunity. Steve had been leading summer research projects in Terengganu, northeast Peninsular Malaysia with ECU graduate students and in conjunction with the Institute of Oceanography and Environment (INOS) at Universiti Malaysia Terengganu (UMT). This collaboration encouraged INOS to expand their oceanography and environment research program to include a geologic component. The chance to do focused coastal geology research on climate change and sea level in Southeast Asia was exciting and filled with possibilities. Much of the basic geologic research (mapping) in what is now Malaysia had been done under British colonial rule, which ended in the 1960’s. Long story short, they hired me and with my wife, Mary Ann, I moved to Kuala Terengganu in January 2012 to join the scientists at INOS.

A New Way of Looking at the World Before coming to Malaysia, I imagined that there would be someone already at INOS with experience in the coastal geology of the region. This, I imagined, would be someone from whom I could learn and with whom I could go on field trips since it would all be new to me. When I arrived, I found that no one like that existed at UMT. Although many communities in Malaysia are dependent on the coastal zone for their food, livelihoods, and homes, little research had been undertaken on coastal zone geology and climate and sea-level change. I became determined to unravel the sea-level history of Malaysia and give this beautiful country tools to anticipate the impacts of future sea-level change. I needed to learn as much as possible about the geology and geography of the Malaysia region before I could decide what direction my research would take. My previous main experience was in Quaternary (the last ~2 million years) paleo-sea-­ level reconstruction and coastal plain stratigraphy. I focused, therefore, on what had already been done related to these topics. I read everything published that I could get online, which was not very much, and bought a fairly recently published book, Geology of Peninsular Malaysia. Digging deeper, I followed all references to previous work. Most of these previous works and reports were hard copies scattered between the Universiti Malaya Geology Department library in the capital city of Kuala Lumpur and the libraries of various Minerals and Geoscience Department of Malaysia offices around the country. I had to go to these places to peruse what was available and decide what I wanted to purchase. I became active in the Geological Society of Malaysia, attended national and regional conferences, and met other geologists with similar interests. Being a geologist in Malaysia is like being a member of a club. Enthusiasm for geology runs high but is primarily focused on mining, resource exploitation and geoengineering. After collecting and reading as much information as I could acquire, I decided to reconnoitre as much of Malaysia’s coasts, coastal plains and islands as possible for evidence of paleo-sea-level. I planned to include both Peninsular Malaysia and Malaysian Borneo, which proved to be no small task.

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Such evidence would include constructional beach ridges and other coastal deposits, erosional scarps and wave-cut notches, encrusting marine fossils on outcrops (oysters, barnacles, etc.), marine/estuarine strata exposed along stream cutbanks or in excavations, and elevated fossil corals and reefs. I would pay special attention to areas where previous researchers documented such evidence and evaluate their measurements and interpretations. Particular emphasis would be placed on the survey of river systems because I expected that former sea-level highstand deposits, if present, would be exposed in cut-banks near the landward margin of the coastal plain where streams dissect these older sediments. These surveys would be conducted using small watercraft, a four-wheeled drive vehicle, or on foot, as conditions dictated. I obtained a grant from the Malaysian Ministry of Science, Technology and Innovation to undertake this work. “Expedisi Malaysia’s Sea Level History” was soon underway! This project was to become a land and sea adventure that took me to almost every island, coastal zone, and on many of the rivers in both Peninsular Malaysia and Malaysian Borneo (Figs.  5.1, 5.2 and 5.3). I found many clues to Malaysia’s sea level past and had the privilege of seeing much of the entire country. I visited most of her coastal communities and experienced the vibrant way of life supported by Malaysia’s relationship to the sea.

More Questions than Answers The primary question for my research was: Is Sundaland, the crustal block centered on the Sunda Shelf (Fig. 5.1), in fact, vertically stable? My four hypotheses were as follows. 1. If the Malaysia region, or portions thereof, have been tectonically stable or experienced uplift during the last several million years then there should be an emergent (exposed on land) record of sea-level highstands that occurred during this time period. 2. If the region, or portions thereof, have been slowly subsiding, emergent coastal deposits will only consist of sediments associated with the mid-Holocene (the last) relative sea-level highstand ~6000 years ago. Any pre-Holocene sea-level highstand deposits will be preserved in the subsurface below modern sea level. 3. If evidence for higher than present pre-Holocene sea levels is found, we can begin to develop the region’s relative sea-level highstand history based on sedimentologic characteristics, stratigraphic relationships, elevations, and ages. 4. If evidence for higher than present pre-Holocene sea levels is not found, the following possibilities would be considered. Evidence has been removed by erosional processes associated with subsequent marine transgressions. Evidence is so intensely weathered and eroded by terrestrial processes that it is unrecognizable. Long-term regional subsidence has resulted in non-deposition on the presently emergent landscape.

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Fig. 5.9  The author’s fieldwork helpers at a fossil coral site in Terengganu, January 2013. From left to right, Emily Parham, Burke Parham, Noraisyah Sapon, Rokiah Suriadi, Noor Azariyah Mohtar, Che Mohd Kamarul Anuar, Granville Parham. (Image by Peter R. Parham)

I undertook this reconnaissance of the Malaysian coasts over a three-plus year period. For some of the NE Peninsular Malaysia field work, I had help from staff and graduate students from UMT, as well as my children (Fig. 5.9). My wife, Mary Ann, accompanied me and helped throughout this undertaking, especially with equipment and accommodation logistics and deployment of a canoe or kayak in streams and rivers. Most of the field work I conducted alone or with the help of various fishermen and boatmen. I was well equipped for this research with a Land Rover, a canoe, a kayak and an aluminum skiff with 25 hp. motor (Fig. 5.10). I used the canoe for most river surveys. My wife would drop me off in the morning and then pick me up at an agreed-­ upon take-out spot downstream at the end of the day. In general, this was a good plan although at times we ran into trouble.

Cutting it Close On one occasion, my take-out goal was a small town downstream on the Kelantan River near Kota Bahru (Figs. 5.2 and 5.11). When Mary Ann reached this town, she could not find a good take-out spot. The town was built atop a very steep hill with no access to the river. Improvising, she drove around further upstream until she found a field with river access. She cut through three family’s properties to reach the access point, obtaining permissions along the way.

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Fig. 5.10  The author loading a boat after field work along the SE coast of Peninsular Malaysia. (Image by Mary Ann Parham)

Fig. 5.11  The author about to launch a kayak from a floating bamboo dock on the Kelantan River, NE Peninsular Malaysia. (Image by Mary Ann Parham)

They hadn’t told her about the pastured cows. Cows in Malaysia are gentle, curious creatures that pretty much wander anywhere at will. These nice cows had cut a path to the water that would be perfect for taking the canoe and equipment out, but the tall shoreline grasses obscured Mary Ann’s position from the river below. While she waited for me, the cows became curious about the big red vehicle parked in the

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middle of their turf. Mary Ann negotiated friendly relations with the cows, but then saw me glide past on the far side of the river, heading further downstream, toward the agreed-upon town. Frantic calls to my phone revealed that my battery had died. After I reached the town and realized the issue, I found a kindly river fisherman who lent me his phone. Now I could find her, but this required paddling back upstream about two miles – exhausting! In the meantime, the cows’ guardians, who spoke no English, came angrily striding out to investigate this random white woman and her Land Rover, apparently messing with their cows. They carried big, well-used parangs (machetes) which could sever limbs with ease. Mary Ann grabbed a large staff of thick teak, part of our standard equipment, and braced it across her chest as she met them, prepared to deflect a machete assault. In halting Malay, she explained that she waited for her husband and explained our Science Expedisi. Machetes came down and were tucked into the back of sarongs as they became interested in this unusual event. When I finally dragged myself up the river bank, it was to quite a reception committee!

Whatever Floats Your Boat Usually it took several days to complete a section of river, especially big ones like the Kelantan. On some rivers, I used my motorized skiff but finding launch sites was always difficult. Although boats are used extensively on the coastal parts of rivers in Malaysia, boat launch ramps are rare. People just keep their boats in the water or pull them up on the shore. While working the Endau River (Fig. 5.2), I put the boat in at a remote Orang Asli (the aborigines of the peninsula) settlement deep within a huge oil palm plantation. By the time I returned, the tide had gone out and the bank was revealed to be a straight down drop. There was no way to winch the boat up the vertical bank to the trailer. Dusk was settling in and most of the villagers had collected nearby to play football (soccer) or sit on the bank chatting. A stack of long wooden poles, the parts of a new deck platform, was piled handily nearby. The locals gave us permission to use them to build a skid ramp to help us pull the boat out of the river and up the bank using a rope extension on the trailer winch. It was a very successful group effort! I used my skiff in coastal waters for surveys of the headlands and close-to-shore islands in SE Peninsular Malaysia. But it was not seaworthy enough for the wind and waves that usually come up in the afternoon. Also, it was hard to run shore surveys where the boat wouldn’t be beaten on the rocks by waves. The islands of Malaysia are often ringed with huge boulders and have poor access in the places where evidence of past sea level is likely to occur. Reaching land can be a treacherous process involving leaping from the front of the boat, loaded with gear, onto large, slick boulders while the boat pitched wildly on the waves (Fig. 5.4). Being crushed between the boat and the boulders was a very real possibility if you missed your mark.

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At one spot where I was able to leave the boat, macaque monkeys boarded it in my absence. They raided my lunch and, when I returned, a monkey was sitting on the deck calmly eating my bag of keropok (Malay fish crackers). In the long run, I found it better and more efficient to hire local boats and boatmen for work around open coasts and islands.

Cultural Differences and Language In order to conduct this type of field research in Malaysia, you have to understand the diverse cultures and their different values. The primary language throughout Malaysia is Bahasa Melayu (Malay language). In places frequented by tourists, like Kuala Lumpur, many people speak some English but most boatmen, usually rural fishermen or water taxi operators, speak little or none. You have to speak enough Malay to communicate, although this is sometimes supplemented with lively pantomime and much laughter. The main ethnic groups in Peninsular Malaysia are Malay, Chinese, and Indian with fewer Orang Asli. Most coastal people and fishermen are Malay and are the best boatmen. Malays are Muslim and you must be aware of, and respect, religious practices and taboos. In Sarawak and Sabah, Malaysian Borneo (Fig. 5.3), ethnicities are more diverse than on the peninsula. Malays and Chinese still make up a part of the population but Indians less so. Here, indigenous tribal people make up a large portion of the population. In Sarawak, the coastal people are mostly either Malay or Melanau (also Muslim). The tribes of the Sarawak interior are loosely grouped under the name Dayak. These peoples were pagan and mostly head-hunters until around the late 1800s. Their pride in this ancestry endures, as does their warrior spirit. Tattoos are an important part of their culture. Most are now Christian (Figs. 5.12, 5.13 and 5.14). In Sabah, the main coastal groups (generally distributed clockwise around the Sabah coast) are Brunei, Bajau (also called Bajau Laut), Illanun, Orang Sungai (mainly in the Kinabatangan River area) and Suluk (east coast Sabah). These are all Muslim. The main tribes of the interior are the Kadazan-Dusun and the Murut. Similar to Sarawak, these tribes of interior Sabah used to be head-hunting pagans but are now mostly Christian.

Tigers and Crocodiles and Cobras…Oh My! Malaysia is primarily covered by jungle. As such, it is still home to occasional roaming tigers (only on the peninsula), wild elephants, deadly cobras, pythons, wild boar, crocodiles and a wide variety of other creatures you would rather not meet personally. Monkeys are abundant and fun to watch but are sneaky and smart. They’ll come into your house and forage, if you’re unwise and leave windows open.

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Fig. 5.12  Iban longhouse on the Rajang River, Sarawak. (Image by Peter R. Parham) Fig. 5.13  Iban (Dayak) tattoos. (Image by Mary Ann Parham)

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Fig. 5.14  Typical waterfront scene on the Limbong River at Pekan Limbong, northern Sarawak. (Image by Peter R. Parham)

I frequently saw huge, battered, stuffed toy tigers sitting on car roofs in many rural areas as monkey deterrents. The most common dangerous creature encountered during my fieldwork was the crocodile (Fig. 5.15). Crocodiles are happy to subsist on a diet of monkeys, dogs, fish, shore birds, people or whatever crosses their path and looks like dinner. When working in Borneo, caution and respect must be your guides. Borneo crocodiles are infamous man-eaters. Attacks and deaths are relatively common. This is not too surprising since many people spend a lot of time around and in the water bathing, washing clothes and fishing, especially along the muddy rivers where crocodiles are most abundant. But crocodiles are also in coastal waters. Brunei Bay and the islands (Pulau) of Balambangan and Banggi off the north coast of Sabah have large crocodile populations, particularly along mangrove-fringed coasts. You must be extremely careful when working in these areas. Crocodiles are lightning fast when motivated, and deadly. Boats do not guarantee protection as crocodiles can snatch prey as they propel themselves over boats and back under water, with their human prize dragged to a violent, horrifying, watery grave. Now that I’m typing this, it sounds kind of bad.

 empting Fate on My Trip to Pulau Mantanani T with the Illanun I planned to survey Pulau Mantanani, a group of three small limestone islands about 25 km off the NW coast of Sabah (Fig. 5.3). I would survey these despite worries about the Illanun, a Muslim coastal tribe in northern Sabah. They have a long

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Fig. 5.15  Large crocodile on the Lupar River in western Sarawak, Borneo. Crocodiles are abundant in Borneo rivers and are man eaters. (Image by Peter R. Parham)

history as pirates, raiders, and shady dealing and are believed by some to have mystical powers. The closest fishing kampung (village) to Pulau Mantanani is Illanun but it was my best bet for sourcing a boatman and boat. At the Illanun kampung, I found a boatman willing to take me out to Pulau Mantanani for a fair price. That was easy, I thought with relief, but as we pushed off four other guys jumped aboard! I’m a fit guy, 6′2″ and former US Marine, but this was worrisome. It is common for a boatman to bring along one helper but four was very unusual. As it turned out, my worries were unfounded. The Illanun boatman and extra crew were a great help, far more interested in joining a Science Expedisi than stealing my dubious worldly goods or head. My ancient, battered backpack probably gave them a clue that I was no rich tourist. I completed surveys of all the islands and we returned to the Illanun kampung safely despite stormy, rough seas on the return trip.

Lost in Translation Clues to northern and eastern Sabah’s sea-level history are preserved in the uplifted fossil coral terraces on Pulau Balambangan and around Semporna (Fig. 5.3). Part of my work in the Kudat area of northern Sabah involved the survey of two large

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islands, Balambangan and Bangi, over 30  km offshore (Fig.  5.3). At the Kudat waterfront I asked around to find a boatman and finally found a Chinese man who ran a fish packing house who called another man who he said might be interested. This was a pretty typical process. After a while, a Bajau man, named Kumai, showed up and we drove to his water kampung, a ramshackle cluster of simple houses on stilts over the water, all interconnected by rickety boardwalks. Kumai spoke no English so we negotiated in Bahasa Melayu as best we could. His smallish, traditional Malaysian wooden boat with a 15 hp. motor was suspended on ropes above the water under his home. The back was covered with a low cabin that was big enough for him to sit in cross legged but, being tall, I found cramped. We agreed on a 5-day schedule and an advance of 200 Ringgit (around $50). The request for an advance was unusual and I was leery that he might just take the money and disappear. It certainly was clear that he could desperately use the money. The next morning, Kumai was waiting at the Kudat waterfront with a case of cola and two styrofoam coolers crammed into the small cabin. I figured he must really like to drink cola. For 2 hours, we chugged out to Pualu Balambangan and spent the day working around the southern part of the island with me going ashore periodically while he waited offshore in the boat. We had a fairly elaborate lunch that Kumai’s wife had fixed. He laid this out in plastic containers on the deck of the cabin and called me to makan (eat) at precisely 12:00 noon. Knowing that it would take around 2 hours to get back to Kudat, at 4:00 pm I said, “balik Kudat” (we go back to Kudat). Kumai appeared confused but after a while we headed back. I suddenly realized that he thought we would stay at the islands for the 5 days I’d contracted him for. He’d come prepared with rations and colas, bought with the advance I’d given him. Next morning, we met again at the Kudat waterfront. This time, Kumai had two 15 hp. motors mounted side by side. We got to Pulau Balambangan in just 1 hour. Every day for the next several, at precisely 12:00 noon, Kumai would lay out the lunch his wife had fixed and call me to makan. At the end of each day, we would “balik Kudat”.

Modern Day Head-Hunters I had serious concerns about working in eastern Sabah and these were well-founded. For years, people have been kidnapped for ransom, often tourists from luxury island resorts, and taken by speedboat to one of the Philippine islands in the Sulu Sea (Fig. 5.3). This archipelago is so huge and intricate, the pirate camps are undetectable. If the ransom doesn’t come through, the hostages are often beheaded. The abduction of two Sarawakians in 2015 and beheading of one of them was only one such episode. The tradition of piracy and kidnapping in the Sulu Sea goes back centuries. Prior to coming to eastern Sabah, I met with geologist colleagues at Universiti Malaysia Sabah and asked how they conducted research in eastern Sabah. “We

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don’t!” was their reply, although they had, in the past, conducted field research under armed police protection. The people at the Sabah Parks headquarters in Kota Kinabalu said that for work in the Semporna area (Fig. 5.3) I should check in with their local office and the marine police before conducting surveys of the mainland and surrounding islands. My first stop in Semporna was the waterfront. It’s typically the best source for dependable boatmen but I quickly realized that Semporna was different from any other place I’d visited in Malaysia. It has the feel of a frontier town and is a hub for the many isolated kampungs (villages) on the islands of the adjacent Sulu and Celebes seas. The population and culture reflect the diverse peoples, many from Philippine and Indonesia territories. The cramped waterfront is alive with watercraft and the boat dock teems with activity. Boats load and unload with quick deliberation as dock space is sparse. Naked boys leap into the filthy, churning water wherever there is space. I was not confident that I would find a reliable boatman here. My second stop was the Sabah Parks office to get research permits. Strict compliance with the authorities is a necessity. The Parks officials recommended a Bajau man named Romy, who turned out to be an excellent boatman. Next stop was the marine police office. Their captain said the waters to the east and northeast, towards the Philippine archipelago that separates the Sulu and Celebes seas, were heavily patrolled by Malaysian security forces and should be safe. The islands to the north were not patrolled because tourists never go there, but they should also be safe. Trusting in my Marine Reconnaissance training and parang, I set out from Semporna town with Romy and his son to work around the Pulau Bodgaya area (Figs. 5.3 and 5.16). The day went well but, on the return trip, we were stopped by

Fig. 5.16  Typical Bajau island village on Pulau Bodgaya, Semporna area of eastern Sabah, Borneo. Every day at low tide, women and children from these villages scour the exposed reef flats and rocks for seafood. (Image by Peter R. Parham)

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Fig. 5.17  Uplifted coral reef limestone at Pulau Selangan in the Semporna area of eastern Sabah, Borneo is likely late Pleistocene in age (perhaps 120,000 years old). In boat, Bajau boatman Romy. (Image by Peter R. Parham)

a speedboat with guys in camouflage, black watch caps and submachine guns. Thankfully, they were a special unit of the marine police. After investigating my boatman, finding out what I was doing, and checking my permits, they invited me on board so that they could all take selfies with me. We parted the best of friends. I spent the following days on remote islands where no tourists ever go (Fig. 5.17). Around these islands, are scattered, small, water kampungs of stilt houses. The people I met while doing shore or reef flat surveys were always friendly and interested in what I was doing. So…no known pirates, no kidnapping and no beheading. I never thought I’d add those to the list of indicators of research success. Make no mistake, working in eastern Sabah is potentially dangerous, especially for foreigners. But working singly with native boatmen, in places where tourists don’t go, is the most low-profile and safe way fieldwork can be done.

A Shell Game So, what came out of this ambitious Expedisi? My several years of field work on Peninsular Malaysia produced a lot of Holocene sea-level data. The main objective of this project, however, was to search for evidence of pre-Holocene sea level(s) higher than modern sea level. I found no such evidence anywhere on Peninsular Malaysia and I felt like I had investigated every possible place. I concluded that either the evidence is not there or I’m not recognizing it. Double checking all

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Fig. 5.18  Uplifted horizontally bedded sandy strandplain deposits (late Pleistocene) overlying older (Cenozoic), tilted sandstone along the northern Sarawak coast. (Image by Peter R. Parham)

locations interpreted by previous researchers as evidence of pre-Holocene high sea level proved to me that they had been misinterpreted and were thus invalid. Some of the highest elevation sites, previously interpreted as evidence of high sea level, turned out to be archeological shell middens where early people had processed seafood under rock shelters or on what would have once been islands. In Borneo, I had surveyed the coastal zone and islands from Tanjung Datu, at the extreme western end of Sarawak, to Tawau, at the southeast corner of Sabah (Fig.  5.3). In the more tectonically active region, northeast of Sarawak’s Lupar River, the paleo-sea-level record is complex and variable. From northern Sarawak to southern Sabah, there is strong evidence for uplift extending into the Holocene. One expression of this likely ongoing uplift is the elevated and extensive strandplain sands that contain trace fossils (burrows) typical of marginal marine environments (Figs. 5.18 and 5.19). A different kind of elevated marine deposit is in the Semporna area of Sabah. These are fossil coral reef terraces that occur up to as much as 10 m above present sea level (Fig. 5.17). Although there have been several attempts (by me and other researchers) to date these terraces using radiocarbon methods, none of the resultant dates are reliable. This is because the fossil coral has been recrystalized with the result that radiocarbon ages are younger than the actual age. It is presumed that these coral reef terraces are of late Pleistocene age, perhaps around 120,000 years old. Based on these examples of well preserved and obvious sedimentary evidence of elevated pre-Holocene sea level in tectonically active northern Borneo, I drew some conclusions about what was likely going on in Peninsular Malaysia. If the peninsula is tectonically stable, there should be sedimentary evidence of at least the last major interglacial sea-level highstand (around 120,000 years ago), which global evidence

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Fig. 5.19  Left panel shows Ophiomorpha trace fossils of burrowing organisms (indicated by white arrows) in a marginal marine environment in uplifted, horizontally bedded sands of probable late Pleistocene age. Right panel shows the same type of trace fossils in the older, uplifted and deformed Cenozoic sandstone that underlies the deposits on the left. Insert shows a close-up of a burrow. Both sites are located between the mouth of the Niah River and Miri, northern Sarawak. (Image by Peter R. Parham)

indicates was between 6 and 10 m above present sea level. The mid-Holocene sea-­ level highstand around the peninsula was only around 3 m above present sea level. Deposits associated with previous, higher sea level(s) should have been inland, above and truncated by mid-Holocene sea-level highstand deposits. Instead, we see deposits related to the Holocene transgression and highstand lapping directly onto much older bedrock surfaces. There is no evidence in Peninsular Malaysia to support the idea that pre-Holocene sea level was ever at or above present sea level, except in much older deformed strata. There is, however, evidence for an older marine unit in the subsurface, several meters below present sea level, that was probably deposited during the last major interglacial around 120,000 years ago. There are no age data yet to support this interpretation. Taking all this into consideration, I concluded that the Peninsular Malaysia region, or at least the coastal parts, must be slowly subsiding over tens of thousands to millions of years. It is supported by other researchers’ interpretations of ongoing subsidence in the South China Sea oil-producing sedimentary basins off the peninsula’s east coast and in the Straits of Malacca.

Paradise Preserved or Being Lost? In any country, there’s an intimate relationship between her coastal people and the sea. It’s timeless, going back generations to the earliest people who were drawn by the salty bounty the oceans provide. It’s a balance, a dependence, a rhythm as

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endless as the tides. Traditions carry forward, such as drying salted fish in the sun before the rainy season, and recipes that honor the gifts that the seas bestow. As with anything observed day after day, big-picture changes, such as climate and sea level, may not be apparent to those living at the coast, even though these changes might threaten their very way of life, sustenance and economy. It’s imperative to be forewarned about possible coastal change. After spending years working alongside the coastal people of Malaysia and their vibrant, rich, Earth-oriented way of life, being able to provide tools to anticipate coastal change is important. To make coastal inhabitants of Peninsular Malaysia alert to the likelihood of sea-level rise and to reassure inhabitants of Sarawak and Sabah that sea-­ level rise will likely not be an issue for their small part of paradise (at least in the near term) is personally satisfying. The Expedisi was all about sea level and climate change and the implications that will be felt by each individual living in harmony with the environment along Malaysia’s beautiful coasts, happily eating Nasi Lemak (rice and tiny dried fish) for breakfast. And, like the tides, the pull of my experiences there will have a profound effect on all aspects of my life. Acknowledgements  I would like to thank Rokiah Suriadi, Noraisyah Sapon, Noor Azariyah Mohtar, Mary Ann Parham and Joseph Bidai for their assistance in portions of this research. I would also like to thank all of the boatmen and other locals from various parts of Malaysia who made much of the field research possible. This research was partially funded by Malaysia Ministry of Science and Innovation (MOSTI) ScienceFund project number 04-01-12-SF0163.

If You Would Like Additional Information Hanebuth TJJ, Voris HK, Yokoyama Y, Saito Y, Okuno J (2011) Formation and fate of sedimentary depocentres on Southeast Asia’s Sunda Shelf over the past sea-level cycle and biogeographic implications. Earth-Sci Rev 104:92–110 Hutchison CS, Tan DNK (eds) (2009) Geology of Peninsular Malaysia. Geological Society of Malaysia, Kuala Lumpur Kamaludin BH (2002) Holocene sea level changes in Peninsular Malaysia. Geol Soc Malaysia Bull 45:301–307 Kessler FL, Jong J (2015) Incision of rivers in Pleistocene gravel and conglomeratic terraces: further circumstantial evidence for the uplift of Borneo during the Neogene and Quaternary. Geol Soc Malaysia Bull 61:49–57 Parham PR (2016) Late Cenozoic relative sea-level highstand record from Peninsular Malaysia and Malaysian Borneo: implications for vertical crustal movements. Bull Geol Soc Malaysia 62:83–104 Tjia HD, Sharifah Mastura SA (2013) Sea level changes in Peninsular Malaysia: a geological perspective. Penerbit Universiti Kebangsaan Malaysia, Bangi

Chapter 6

What Lies Beneath? Revealing Coastal Processes Through Mapping J. P. Walsh

Abstract  Coastal areas are changing as a result of natural and human activities, and these dynamics create risks for citizens and communities. Science is needed to map and measure coasts and oceans, and many new tools exist  to enhance our knowledge. In this chapter, some of the methods being employed around the world  are discussed including GIS, multibeam sonar and aerial imaging. Stories from past and recent research are used to explain the approaches as well as their scientific and societal value. Weaving together experiences from ancient worlds, on distant shores and with crocodiles, I explain how and why we learn about what lies beneath the waves and along our shores. Keywords  Coast · Sediment · Shoreline · GIS · Mapping · Multibeam · Outer Banks · North Carolina · Papua New Guinea · Rhode Island

An “Aha” in an Ancient Ocean The ocean is scary. Many people hear the “Jaws” theme song when they take a dip in the sea. Sometimes I do too. Coastal geologists and oceanographers like myself want to understand what lies along the shore and underneath the sea. Every coast and every ocean has a story, and we seek to reveal it. This exercise is as much about learning about the future as it is about the past, especially as communities plan for the next storm or decades of sea-level rise. By measuring and mapping the land and sea, we can determine the location of valuable resources, such as sand to maintain shorelines or long-lost habitats. As a surfer I must add that I am more scared about what the sea will do to our coast than I am about a shark nibbling on my limbs.

J. P. Walsh (*) Coastal Resources Center, Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA e-mail: [email protected] © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 S. J. Culver (ed.), Troubled Waters, Springer Climate, https://doi.org/10.1007/978-3-030-52383-1_6

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My story starts in Upstate New York, USA, far from the modern coast, but home to an ancient one. I was a geology major at Colgate University in Hamilton, New  York. In the Devonian, about four hundred million years ago, the Atlantic Ocean did not exist, but as its predecessor closed, shallow seas covered some of the interior of the eastern United States. In a quarry near campus where some friends and I used to rock climb, I found my first large fossil. It was a Mucrospirifer mucronatus brachiopod, I believe – a cool-looking clam-like organism that lived in warm, shallow areas. This moment gave me an appreciation for how ancient times influence today. Several of the buildings on campus were constructed of stone from the quarry, including the one where I lived my first year. Ironically, landlocked Colgate was a wonderful place to learn about the sea and its effects on the coast. There were two accomplished and inspiring marine geologists on the faculty, Drs. Charlie McClennen and Paul Pinet. I won’t digress into telling stories, but I must give them credit for inspiring my oceanographic interests. Additionally, there were several other Colgate geologists who helped me appreciate the forces of the Earth and its history, including Art Goldstein (structural geology), Di Keller (mineralogy), Jim McLelland (a.k.a., “Chief”), Connie Soja (paleontology), Bruce Selleck (sedimentary geologist) and others. I start my story here not only to reminisce but also to explain my “Aha” moment for coastal mapping. Also, I think it is important to remember the impact of intellectual inspiration; these scientists and others mentioned are just a few of many that helped me along my research path. As a senior, I had a project that involved analysis of the coast. More specifically, I obtained aerial photographs of the Long Island (NY) shoreline before and after a powerful nor’easter in 1992, and I wanted to map and measure the storm’s impact. By georeferencing digital aerial images (a fancy way of saying – put them in the same spatial coordinate system so they could be overlain), I was able to visualize the influence of the storm surge and subsequent erosion of the shore. Once the images could be superimposed, I identified the homes destroyed due to the opening of an inlet after the storm – over 70 if I recall correctly. This multi-million-dollar erosion event still stands out in my mind. I find it rather amusing that this stretch of shore has since been repopulated with houses (Fig. 6.1). Remarkably, the area survived Hurricane Sandy in 2012 without major damage, but I know it is only a matter of time before the ocean rises again. This small student project allowed me to better understand how and why ocean science is needed for our coastal communities.

Study Seafloor Dynamics from Space? When taking a remote-sensing class at the State University of New York – Stony Brook (now Stony Brook University) in 1995, I was impressed how aerial photos were used to reveal ancient structures in the Middle East, thanks to Dr. Elizabeth Stone. I was convinced that satellite-based ocean measurements would be the wave

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Fig. 6.1  (Top) Aerial photograph of a portion of Westhampton Beach, NY, USA, approximately 1.5 years after a storm in 1992 eroded through the island. Dozens of homes were lost when the inlet opened; the inlet was closed by April 1994 (Image from Google Earth: U.S. Geological Survey). (Middle) Aerial photograph of the same area today (Image from October, 2017, Google Earth: Landsat Copernicus). (Bottom) Zoomed-in view of houses visible in recent aerial imagery (see black bracket in the middle panel for location). (Also from October, 2017 – Google Earth: Landsat Copernicus)

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of the future for coastal ocean research. Already, satellite sensors such as the Coastal Zone Color Scanner had produced spectacular images of ocean phytoplankton blooms. I believed they could also inform the sediment dynamics near rivers. My advisor, Dr. Chuck Nittrouer, thought I was nuts. He logically explained that visible light only penetrates the uppermost layer of the ocean, and most sediment moves near the seafloor. He was right. Nevertheless, I was certain that remotely sensed imagery could be used to inform what is happening at the ocean surface, and this would indicate what transpires on the ocean floor below – at least sometimes. I was right too. In fact, most people don’t know that most of our maps of bathymetry (ocean depths) are based on satellite measurements of the sea surface elevation (not the seabed). Altimetry measurements are used to calculate the depth of the seafloor and corrected using local measurements where available. From the combination of space and ship-based data, our global maps of the seafloor are still derived today. Of course, we have much better knowledge of the depths in well-trafficked coastal zones, especially near ports. But many don’t realize that only 18% of the ocean floor has been mapped at a resolution of 1 km or less – more on that later. The point I want to make here is that remote sensing now provides tremendous information about our coasts and oceans. An arsenal of satellites using a variety of techniques (not simply visible light) measure the dynamic earth and its coastal and ocean phenomena. We still have many limitations in our sensing abilities temporally and spatially due to resolution, cloud cover and other factors, but our ability to study the global coast has greatly improved. One of my favorite images of coast was captured following a storm in February 2010 (Fig.  6.2). This MODIS (Moderate Resolution Imaging Spectroradiometer) image reveals how the shallow waters of the Albemarle and Pamlico sounds in northern North Carolina were stirred up by the wind-generated waves and currents during the storm. The dark-colored water, filled with sediment and dissolved materials from land, is being carried out of the inlets at the eastern side of this large estuarine system. Once on the NC shelf, the sediment-laden water is entrained in nearshore currents moving along the coast and eventually by the Gulf Stream into the open Atlantic. Images like these highlight the potentially rapid connection between land and sea, a research topic we continue to learn more about. During storms, we know the estuarine seafloor is being agitated because we can see it in satellite imagery, have measured the conditions (Fig.  6.2, Top) and have experienced the power of storms first-hand. My colleague, Dr. Reide Corbett, and I along with several former students and collaborators, deployed instrumented tripods in these areas. There are many stories from our times in the field. One of the most memorable was when a strong thunderstorm descended upon on our team as we worked at the “Albemarle Sound Site”, located in the middle of the vast body of water. We affectionately referred to this location by its acronym (the ASS), because things had a propensity for going wrong. On this day, an ominous storm system descended upon on us (Fig. 6.3). Lightening was shooting like fireworks in all directions as the storm approached, and we were very exposed -- on a small boat tied up to a metal piling with nowhere to find shelter. Without time to finish our work or

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Fig. 6.2 (Top) Measurements of wind speeds and waves in Pamlico Sound, North Carolina, USA, as a storm passed in February 2010 (Walsh data). (Bottom) Satellite image of Pamlico Sound showing sediment resuspended by the wave action, transported into the ocean, and carried by the Gulf Stream. (MODIS image from NASA)

return to our launch location, we sped across the bay chased by lightning, thunder and torrential rain. We eventually found protection in a marina convenience store and played cards until safe skies returned.

 easuring Sedimentary Processes in Papua New Guinea M with GIS If you have not heard of GIS (Geographic Information Systems), you should be aware of this important digital approach/software for analyzing human and environmental data. It is being used around the world today to examine spatial relationships in data, such as communities mapping critical infrastructure or businesses examining revenues for different locations. I realized the power of GIS when I worked on

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Fig. 6.3  A thunderstorm that descended upon our field research team in the Pamlico Sound, North Carolina. (Image by J.P. Walsh)

my dissertation at the University of Washington. As a Ph.D. student, I was fortunate to have an incredible project working in Papua New Guinea. If you’re not familiar with the country, it is positioned immediately north of Australia’s Great Barrier Reef and is comprised of the eastern half of the island of New Guinea as well as a few other islands. PNG, as it is often referred to, is a wonderfully wild place. Stories of cannibalism and pictures of men with penis gourds are still produced today. It is a country rich in amazing natural beauty whose resources are being exploited extensively, and its unemployment and poverty have led to social and security challenges. With Google Earth, anyone can now explore remote places in PNG from the comfort of one’s living room. If this technology existed back then, I might have reconsidered the travel! To get there for field work, one of my first trips used a ship from Thursday Island, located just off the northeastern tip of Australia. After days of travel, I arrived at this little island at the northern end of the Great Barrier Reef. Once onboard the ship, I was told the research cruise might not occur because the cook and one of the crew had come down with an unknown disease after returning from our destination! But sometimes life is serendipitous – the ship got some new crew (the other crew eventually recovered), and we headed to PNG. Determining coastal dynamics or other spatial changes over time often requires a birds-eye perspective. I won’t get into the details of my dissertation, but in short, I was trying to understand how the sediments pouring down from the large, wet and rugged island of New Guinea flowed into the ocean and then are moved by currents, waves and tides into sedimentary deposits on the ocean floor. Yes, it was a truly overambitious effort, especially considering the scale of the system. But I was young and optimistic, and my advisor, Dr. Chuck Nittrouer, was a legend for such

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studies. He and a large team had studied the mighty Amazon, through many oceanographic field investigations. An important difference of PNG is that it is home to man-eating saltwater crocodiles! And unfortunately, the malaria medication I was taking was giving me vivid nightmares of being attacked. One story from PNG always brings a smile to my face. After two days of steaming north aboard the R/V Harry Messel we encountered very rough seas in the Gulf of Papua. We abandoned our plan to go farther north to the Purari River mouth and instead retreated westward to the expansive Fly River. After navigating upstream for a day, we anchored and got prepared for coring. The next morning, we embarked on an inflatable boat into the maze of mangroves in the delta. I was nervous but excited to collect my first core. In fact, I had never used the vibracoring system before, but I was pretty certain I’d figure it out. After a little exploration, we found a gently sloped muddy bank for our first sampling attempt. As we waddled up the bank through knee-deep mud with heavy gear, thoughts of being a crocodile’s lunch weighed heavily upon my mind. Struggling to find firm footing, we put down some plywood squares to work on. Soon after I stepped atop the “platform”, I found myself surfing down the mudbank towards the murky water below. Terrified of the sure-to-be-lurking reptiles, I was launched face-first into the mud-laden waters. Realizing I wasn’t consumed, I laughed and humbly trudged through the mud back to work. Sampling the first site was a success, and many more cores soon followed (Fig. 6.4). We only had one scary encounter with a croc, but the 10+ ft. (3 m) toothy beast was just as scared as we were.

Fig. 6.4  The author covered in mud and surrounded by mangroves in the Fly River delta of Papua New Guinea. GIS was needed to place the sediment cores in a broader context of the delta system. (Image by Dr. Gregg Brunskill)

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So why is a Geographic Information System (GIS) useful? Imagine randomly visiting ~30 locations across the entire NY metropolitan area and then trying to estimate the total number of cars in the City. Without knowing the number of roads or parking lots, this would be impossible. In my study, GIS enabled me to map all of the similar environments (waterways, shallow areas) and identify areas similar to where I sampled. Using this information, coupled with analyses from the cores, river morphology and bathymetry offshore, I estimated the sediment being trapped in the study area vs the total amount coming into the ocean. This work is fundamental to determining how materials from land are dispersed in the sea. My doctoral work also highlighted the importance of mangroves in storing sediment and carbon, another topic receiving much attention as nations grapple with too much carbon dioxide in the atmosphere.

Mapping the Coast with Lasers, Acoustics, and Robots Today there is a lot of cool technology that we can use to better understand Earth surface dynamics and history. The most widely used tool for studying the seafloor is sonar. Developed during World War I and used heavily during World War II, the technology has come a long way. Now we have sophisticated acoustic systems that can measure depths over a swath of the seafloor using a fan of sound propagating below a ship or other device. It is with these systems that we can now “see” the seafloor and use this invaluable information to measure and determine governing processes, such as submarine landslides or wave-reworking by storms. During my time at East Carolina University (ECU), a couple colleagues, Drs. Reide Corbett and David Mallinson, and I obtained a grant from the National Science Foundation to obtain state-of-the-art tools for studying the coastal areas. The problem with mapping the seafloor with fancy, expensive equipment is that one does not know the depths prior to the first mapping. Often the information on nautical chart is decades old. For testing of our ~$150,000 new seafloor mapping instrument, we went to Washington, North Carolina, where we could use an ECU vessel as a survey platform. After getting the system set up and going, we were thrilled by the results and wanted to see more in harbor. We passed under an old bridge and could see individual pilings and other structures to the side of the vessel, but as we came out the other side, the depths got shallower … and shallower… and shallower. The seafloor quickly came within inches of the sensor, and we scrambled to tilt up the device and slow the boat. Thankfully before any impact, the water began to deepen. It is terrifying to think that we almost destroyed the costly system on the first day. But this is ocean science. Conditions are dynamic and often dangers are unknown. It was this same multibeam system that we used aboard the R/V Cape Hatteras to map seafloor change after Hurricane Katrina and civil war wreckage in coastal North Carolina (Fig. 6.5). More and more vessels have this type of technology integrated with their navigation and other systems. As a result, new data are being

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Fig. 6.5  High-resolution bathymetry of a portion of the Roanoke River, North Carolina near Plymouth. Remnants of a blockade from the Civil War have affected the character of a field of sand waves on the river bottom. (Image by J.P. Walsh)

collected all the time around the world. As you read this chapter, there are dozens, maybe hundreds, of ships from the Arctic to the Southern Ocean, mapping the seafloor. Some are “mowing the lawn” as part of a formal survey (which can be rather monotonous) while others are just collecting data as the vessel transits from port A to port B. If you want to see what an expedition is like, you can now experience them virtually through “telepresence” with the University of Rhode Island’s Inner Space Center (http://innerspacecenter.org/); mapping and seafloor exploration is regularly livestreamed from local and remote areas of the ocean. There is a global push now to map the entire ocean by 2030 – a grand goal. However, with so many ships now crossing the seas, and new autonomous platform coming online (e.g., competitors for the Shell Ocean Discovery XPRISE teams, https://oceandiscovery. xprize.org/prizes/ocean-discovery), this aspiration is not so unrealistic. A great challenge will be integrating so much information from disparate sources, but the Seabed 2030 effort appears to be well-orchestrated and already having success. Today, we have systems that beam lasers to map elevations very precisely, and when coupled with extremely accurate GPS (known as real-time kinetic or RTK GPS), it is possible to map coastlines and structures to centimeters of  precision. Additionally, we have many types of optical and acoustic sensors mounted on drones or underwater platforms that enable us to map at very fine (several centimeters or less) or over large scales with satellite data. A variety of remote-controlled vehicles (i.e., robots with cameras or other sensors) can now accurately and quickly survey sites during or after events, giving invaluable insights on impacts. “Seeing” the coastal landscape and seascape with its subtle topography, often masked by

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vegetation, is invaluable to environmental research. By repeating measurements, we can look at changes over time, such as the erosion induced by overwash (water washing over the land) during a hurricane. One approach used by my colleagues, Drs. Devon Eulie and Reide Corbett, and I was a balloon-mounted digital SLR camera. This portable system was relatively easy to deploy, although rather bulky and dependent upon low wind speed (Fig. 6.6). We used this platform to collect periodic high-resolution (pixels of several centimeters) imagery over more than a 1-year period. These data allowed us to visualize and measure short- and long-term coastal changes. The work was informative to estuarine shoreline mapping we had conducted throughout NC for the Division of Coastal Management. Also, by combining mapped changes with wave information from measurements and models, we were able to demonstrate how wind-driven erosion can cause potentially rapid shoreline

Fig. 6.6  (Top Left) Dr. Devon Eulie, a former Ph.D. student, prepares a balloon-camera system on the inland margin of Pamlico Sound. (Right) Photograph showing the balloon-camera system in operation. (Bottom Left) Aerial image collected after Hurricane Earl in 2010 from the balloon-­ camera system (from Eulie et al. 2013). The orange line indicates the shoreline on the post-storm image from October 2010. The red and yellow lines are shoreline positions mapped in June and August 2010, respectively, before the passage of Hurricane Earl in September 2010. (Images by J.P. Walsh)

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retreat. The balloon was tethered to a winch on the ground or a boat, and this provided extra security, but moving helium tanks was not easy. Now similar work can also be accomplished by aerial drones. A nice example of modern capability comes from research by a former ECU Ph.D. student, Ian Conery. He used a sophisticated terrestrial laser scanner to map change in two beach-dune areas of the Outer Banks, NC, one a relatively undeveloped location at the US Army Corps of Engineers Field Research Facility in Duck, NC and the other, a more developed area near Jennette’s Pier, Nags Head, NC. His work highlights how a recent beach nourishment project in Nags Head led to localized accretion in the dune system. Figure  6.7 demonstrates the incredible detail visible using laser-based mapping. By remapping areas, for example before and after a storm, much information can be obtained. More research is needed to better understand the complex dynamics along our coasts, and to apply local insights to other areas, it is important to combine mapping with measurements and models as done by Conery. New mobile measurement platforms are now available to examine hard-to-reach or large areas, so after storm events, coastal managers and communities can better understand impacts and plan recovery. For example, the U.S.  Geological Survey regularly uses airplane-based laser mapping (LiDAR) to perform change assessment after hurricanes, such as Hurricane Matthew in 2016 (Fig. 6.8). Additionally, now with computer forecasts prior to storm landfall, states (e.g., NC, https://fiman.nc.gov/) and the federal government (e.g., USGS, https:// marine.usgs.gov/coastalchangehazardsportal/) have tools to maps coastal flooding and areas of expected shoreline change. Drones, or more officially, Unmanned Aerial Vehicles (UAVs) are now being used extensively around the world not only for fun videos but also for research and resource management (e.g., crops). Over a decade ago our lab group acquired our first drone. It was a relatively high-end unit, costing about $5,000. But, despite the drone’s capability, my first flight did not quite go as planned. It was a breezy day, and I was anxious to give it a test flight after it was fully assembled. I read the manual, but it was rather cryptic. After studying up, I brought the system outside of the ECU Coastal Studies Institute (CSI) building and tentatively pushed the two levers together to initiate power. The drone fired up quickly and felt robust and powerful. I immediately shut it down. After a few repetitions, I was a bit more comfortable, so I decided to lift the drone a little off the ground. Success! I quickly lowered it, and then repeated the lift-off process, and even spun it around and snapped a few pictures. Now, I was feeling pretty good, so I next decided to go a bit further. I raised the drone up higher … and then a bit higher. The wind quickly began to push the drone towards the CSI main building. I tried to adjust but soon the drone was beyond the roofline. I throttled down hard, hoping it would land on the roof. I ran around the building and realized it had gotten quite dark, and I couldn’t see drone lights anywhere. Now, I was thinking/hoping it was on the roof, but as I circled back to the takeoff point, there it sat, with its lights flashing. As the video later showed, the drone had drifted maybe a quarter of a mile before its homing protocol kicked in, and it returned automatically. I was so relieved to have it back! Today, these aerial platforms are widely employed for coastal

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Fig. 6.7  Area of the Outer Banks in Nags Head, North Carolina examined using terrestrial-laser scanning over time. (Top) Google image of the area in March 2017. Color images in the middle reveal mapped elevation changes (note scale) associated with storms in February (left) and October 2016 (right, after Hurricane Matthew). Images at the bottom show erosion adjacent to a boardwalk (left) and accretion on a dune top (right). (Images from Conery et al. 2020)

investigations  (note:  with better  safety protocols!). One exciting application of drones is using them to create 3D models of the landscape to measure volume losses in beaches and dunes. To create such a digital elevation model (DEM) requires powerful computer hardware and software. In a process known as Structure from

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Fig. 6.8  Maps showing coastal changes in North Carolina based on aerial LiDAR associated with Hurricane Matthew in 2016. (From the the USGS, Birchler et al. 2019)

Motion, images from different angles are stitched together using computer-­identified common points: decimeter-scale horizontal and vertical topographic variations can be seen. In some ongoing research, my ECU colleague Dr. David Lagomasino and I are using aerial drone and boat-based acoustic and video observations to ground-­ truth habitat large-scale mapping with satellite imagery in the Philippines (see Lagomasino chapter). This work is part of the USAID Fish Right Program to help communities and agencies better manage fish resources. We now have amazingly capable drones and other vehicles for mapping from the water surface and below it. For example, remotely controlled jet-driven kayaks or other boats can measure water properties and image seafloor areas with echosounders, including multibeam. Even more impressive are fully autonomous underwater vehicles that can survey large areas of the seafloor and inaccessible locations (e.g., under glaciers) to not only determine the shape of the seafloor, sometimes called the “seascape”, but also what lives on it. Several exciting AUV examples competed for the aforementioned Shell Ocean Discovery Xprize. To see what is possible today,  Figure 6.9 is an image from HabCam (https://habcam.whoi.edu/) a towed benthic habitat mapper being used by NOAA to quantify scallop and other demersal life on continental margins. The latest version of HabCam is an AUV system.

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Fig. 6.9  HabCam image of Atlantic continental shelf showing sand dollars and a fish on a sandy seafloor. (Image by NOAA 2018)

Sophisticated technology like HabCam and other mapping tools are critical if we are to understand how human- and climate-driven changes are affecting our oceans.

The Future Will Be Fascinating I am now a Professor in the Graduate School of Oceanography at the University of Rhode Island (URI). In January 2019, I had the opportunity of participating in the 77th Multibeam Sonar Training Course (https://mbcourse.com/). It was a fabulous, intensive week-long training on sonar theory, systems and more. The final day discussed the future of navigation, and it was fascinating. Our technology for mapping the sea and shore has grown tremendously over the last few decades. As our data collection methods improve, so will our ways to fuse and visualize the vast volumes of information. Electronic nautical charts coupled with other satellite-derived information will allow us to measure and map dynamics of our coastal zones with great precision in near-real time. Now, all large ships are required to have electronic nautical chart capability, and in the future, traditional paper charts are likely to be largely just used for decoration. Integration of varied types of data in real time to produce a more informative and effective tool for the navigator, recreational boater

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or scientist is where we are heading. This will empower people to better understand and use information for safety and fun. For example, the University of New Hampshire, private companies, and various organizations are working toward the Chart of the Future (http://ccom.unh.edu/theme/chart-future). Of course, most of us live life on land and have concerns about how the sea may impact our homes and  communities. In my current position as Director of the URI Coastal Resources Center, my colleagues and I aim to bring together science and stakeholders to help solve societal issues. I know how new technology is already helping us plan for coastal use and changes, as evidenced by STORMTOOLS (http://www.beachsamp.org/stormtools/) developed as part of the RI Shoreline Change Management Plan. Online applications like STORMTOOLS, can allow data and model results to be combined, to help decision makers and the public as they prepare for and respond to storms and sea-level rise. Additional new datasets and technologies will provide important new insights, particularly as climate change affects our coasts and resource conservation and management become even more critical, especially in developing countries. GIS and remote sensing will be increasingly valuable as communities strive to manage their shores sustainably. Sharks and crocodiles will be the least of our worries. Acknowledgements  Support from various funding agencies has enabled the research discussed above and much more, including the National Science Foundation, NOAA, USAID, and the states of NC and RI. In addition to those mentioned, many individuals have contributed to my growth and knowledge, and I have great appreciation. Academic colleagues, staff and so many students have contributed in countless ways from intellectual development to logistical assistance. The captains, crew and on numerous vessels kept my colleagues and me safe and enabled our work. Support from family and friends has been vital to allow me to travel far and wide and work often extended hours.

If You Would Like More Information Alongi DM (2014) Carbon cycling and storage in mangrove forests. Annu Rev Mar Sci 6:195–219 Amante C, Eakins BW (2009) ETOPO1 1 Arc-Minute global relief model: procedures, data sources and analysis. NOAA Technical Memorandum NESDIS NGDC-24. National Geophysical Data Center, NOAA, Boulder. https://doi.org/10.7289/V5C8276M Birchler JJ, Doran KS, Long JW, Stockdon HF (2019) Hurricane Matthew—predictions, observations, and an analysis of coastal change. U.S. Geological Survey Open-File Report 2019–1095, 37 p. https://doi.org/10.3133/ofr20191095 https://pubs.er.usgs.gov/publication/ofr20191095 Conery I, Brodie K, Spore N, Walsh JP (2020) Terrestrial LiDAR monitoring of coastal foredune evolution in managed and unmanaged systems. Earth Surf Process Landf 45:877–892 Eulie D, Walsh JP, Corbett DR (2013) High-resolution measurements of shoreline change and application of balloon-aerial photography, Albemarle-Pamlico estuarine system, North Carolina, USA. Limnol Oceanogr Methods 11:151–160 Eulie D, Walsh JP, Corbett DR, Mulligan R (2017) Temporal and spatial dynamics of estuarine shoreline change in the Albemarle-Pamlico estuarine system, North Carolina, USA.  Estuar Coasts 40:741–757 Mayer L, Jakobsson M, Allen G, Dorschel B et al (2018) The nippon foundation—GEBCO seabed 2030 project: the quest to see the world’s oceans completely mapped by 2030. Geosciences 8:63. https://doi.org/10.3390/geosciences8020063

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NASA (2019) NASA’s earth observing system. https://eospso.nasa.gov NOAA (2018) Press release. https://www.nefsc.noaa.gov/press_release/pr2018/features/ scallop-research-surveys/ Rather JT (2003) West Hampton Dunes: back from brink. New York Times, 8 August 2003. https:// www.nytimes.com/2003/08/10/nyregion/west-hampton-dunes-back-from-brink.html Smith WHF, Sandwell DT (1997) Global seafloor topography from satellite altimetry and ship depth soundings. Science 277:1957–1962 Terchunian AV, Merkert CL (1995) Little pikes inlet, Westhampton, New  York. J Coast Res 11:697–703. https://www.jstor.org/stable/pdf/4298373.pdf?refreqid=excelsior%3Af287ddd12 fb0b880e0721db89c5afab7 Walsh JP, Nittrouer CA (2004) Mangrove-bank sedimentation in a mesotidal environment with large sediment supply, Gulf of Papua. Mar Geol 208:225–248 Walsh JP, Corbett R, Mallinson D, Goni M et al (2006) Mississippi Delta mudflow activity and 2005 Gulf Hurricanes. Eos Trans AGU 87:477–478. https://doi.org/10.1029/2006EO440002

Chapter 7

The Anthropocene, Wait, What? A Basque’s Coastal Experience Helps to Figure It Out Eduardo Leorri

Abstract  At the very end of the twentieth century I was working on my PhD project that included getting (knee) deep into the mud of the Bilbao Estuary (Northern Spain) to understand the environmental evolution of this system dramatically altered by anthropogenic activities. Almost concomitantly, a new term to describe the period during which humans have become major drivers of change was coined: “Anthropocene.” This chapter briefly narrates my experience as PhD student and how it led me to adopt this term to identify sediments reflecting predominantly human activities and why (in my opinion) this term is relevant. Keywords  Anthropocene · Estuaries · Pollution · Bilbao estuary · Micropaleontology · Coastal environments · Sediments · Holocene · Heavy metals

Why the Anthropocene? So, what is the Anthropocene and why is it important? To answer this question, I need to first tell you about the Holocene. The Holocene has been formally recognized since 1885 (Gervais first used the term circa 1867) as the latest interval of geologic time (an epoch), although the beginning of this interval was formally defined and dated at 11,700 years b2k (before 2000 A.D.) only a decade or so ago. Together with the immediately preceding Pleistocene, these two epochs are the subdivisions of the Quaternary geologic period. At its 10-year anniversary (in 2018) the Holocene was formally divided into three ages to reflect the use of three informal divisions (early, middle, and late Holocene), which are recognized now by the International Commission on Stratigraphy. The Holocene, which means the “entire recent”, might well be the most studied part of the geologic record, and it includes E. Leorri (*) Department of Geological Sciences, East Carolina University, Greenville, NC, USA e-mail: [email protected] © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 S. J. Culver (ed.), Troubled Waters, Springer Climate, https://doi.org/10.1007/978-3-030-52383-1_7

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the present day and covers the time span over which human civilization developed following the last ice age. Since 2000 A.D., when Paul Crutzen and Eugene Stoermer first coined the term “Anthropocene” (anthropos = human, cene = recent) to represent the period of time during which humans have had an impact on Earth’s climate and environment, it has been widely used and geologists have increasingly asked whether the most recent part of the Holocene should be recognized as a new, post-Holocene geological epoch. This question has been raised because human beings have become so numerous and our agricultural and industrial activities have been and still are so pervasive that our actions have affected the nature of sediments preserved in the latest Holocene geologic record. Discussions of whether the term is necessary have been lively and the jury is still out on whether or not the Anthropocene will become formally defined as a geologic epoch. The level of debate that the term Anthropocene has generated has extended beyond geologists. Members of other academic disciplines are weighing in and the Anthropocene has even been mentioned in the media. To complicate matters further and while it is not yet formally defined, the age of the commencement of the Anthropocene is a particularly contentious topic, although it seems now that it will be placed in the mid-twentieth century, linked to the sometimes-heated debate regarding human-driven climate change. Despite the controversy, the Anthropocene has a special meaning for me because it was the physical and chemical alteration, by human activity, of the place where I was born that sparked my interest in the geologic study of modern environments. I am from the Basque Country in northern Spain, from a town facing the port of Bilbao on the southern margin of the Bay of Biscay. My career in geological research started in 1997 after I was awarded a national (Spain) doctoral fellowship. I had applied for this funding the previous year without knowing what to expect due to the highly competitive nature of these grants, although with great excitement about the project that I had proposed. Maybe my excitement came through in my proposal! All I knew was that a great opportunity had been presented to me and I was going to make the most of it.

Why Bilbao? A Bit of History Given our location and my interests, my PhD advisor and I decided that we should study the environmental evolution of the Ría de Bilbao (the Bilbao estuary) and the anthropogenic (meaning human-caused; this is the key to this story) impacts in this body of water (Fig. 7.1). Our study would encompass the last 8500 years of geologic time, corresponding approximately to the Middle and Late Holocene. Now, why in the world would you study the last 8500 years to understand anthropogenic impact? Well, if we take a look at Figs. 7.1 and 7.2, it is easy to see that there is no single place in the Bilbao estuary that has not been modified by human activity. Therefore, the only way to know and understand the environment is to

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Fig. 7.1  Google Earth image of the Bilbao Estuary (2017) and a general location map (square box indicates the location of the Bilbao estuary on the northern coast of Spain)

Fig. 7.2  Pictures of the Bilbao Estuary in the late 1990s while sampling surface sediments and taking cores. These pictures illustrate the lower and middle reaches of the estuary and reflect the dramatic modifications made during the last several centuries. (Images by E. Leorri)

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Fig. 7.3  Example of how the intertidal environments in the Bilbao estuary might have looked a few hundred years ago. The picture was taken during 2008 in the Urdaibai estuary near Bilbao). We can see marshes, tidal flats, creeks and the estuarine main channel. Compare with Fig. 7.2. (Image by A. Cearreta)

investigate the geological record prior to significant human modification and reconstruct the natural conditions of the estuary over the last few thousand years. So, look at Figs. 7.1 and 7.2 and mentally delete all the urban and industrial spaces. Imagine a place without factories belching fumes, without sea walls, quays and polluted mud. Replace this human influence with the almost pristine estuarine environments that we see in Fig. 7.3; that is how the Bilbao estuary was before humans occupied it. Indeed, we know that, just 130 years ago (1891 A.D.), Wilhelm von Humboldt, a visiting Prussian philosopher, linguist, government functionary and diplomat, described the view of the Bilbao region as something that has to be experienced (a small paradise), despite the fact that the region in 1801 was already busy with industrial activity. Mining activities in the Bilbao region were reported by Pliny during the first century and there is archeological evidence of Roman mining activity in the nearby estuary of Bidasoa. The city of Bilbao was established in 1300 and by the nineteenth century the iron industry dominated the economy of the region and contributed to the intense transformation of the natural environment. But it was during the 50 years between 1876 and 1925 that this activity became the centerpiece for the economic prosperity of the region. The revenue from mining served to provide financial support for development of the iron industry. By the last quarter of the nineteenth century, the bucolic landscape that Humboldt described had been transformed and replaced by fumes, smoke, industries, railways, and urban development.

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Deforestation was changing the hills, and wetlands, dunes, and other coastal environments saw the installation of factories, houses, and other structures. By 1902 several iron smelting facilities merged into “Altos Hornos de Vizcaya S.A.” and the expansion of this industry led to the development of the railways to transport the iron. At that time, there was already an “industrial fog” and water pollution was significant. Between 1900 and 1916 two of the main shipbuilding companies were established in the estuary. This activity resulted in other industries also coming to the region. The major expansion of industry was really quite recent and commenced around 1950 with intense harbor development to exploit the natural resources of the region (mainly iron). Maritime activities have always been important in the Bilbao estuary. Several centuries ago, a sand spit close to the mouth of the estuary limited navigation to high tides only. Large ships could navigate the waters only during the exceptionally high waters during spring tides (at full or new moon). Significant modifications had started by 1502 by changing the main channel of the Gobelas tributary. The main channel was significantly altered in 1654 to minimize the seasonal flooding that Bilbao suffered regularly. In 1753, quay walls and piers were built in the lower reaches on both banks creating a single straight channel that was also dredged. Unfortunately, this led to sand accumulation at the mouth of the estuary. The sand spit remained until 1877 when an iron dock on the left bank at the mouth of the estuary was extended. Between 1891 and 1905, breakwaters were built, sheltering a large section of the bay. During 1907, several areas on the left bank leading to the fishing harbor in Santurce were artificially filled. It was not until the 1970s that El Abra bay, seaward of the estuary, was enclosed with the construction of the breakwaters on both sides (Figs. 7.1 and 7.4). Our project started with the basic premise that all natural and anthropogenic changes that have affected the Bilbao estuary and environs are recorded in the sediments stored in the Bilbao estuary. The idea was that we could use industrial metal concentrations and microfossil data to see how the history of the Bilbao estuary was recorded in these sediments and provide guidelines for the recovery process. The microfossils we used to reconstruct past environments and to indicate intervals of pollution were foraminifera (Fig. 7.5), single-celled organisms whose shells are so small that several can fit on the head of a pin.

Getting into the Mud! We had fun (if that is the right word) when we started looking at modern sediments within the estuary. We took many kinds of samples – surface grab samples, push cores, percussion cores, auger cores, drill cores. In Fig. 7.6, we can see two of the surface sampling sites. In this case, there was little equipment needed – a small ring to select standard-sized samples, a spatula (to recover the sediment), and a jar with a solution that prevents the degradation of the organic matter (we needed to know if there were living organisms in the sediment). But the scientific papers we wrote do

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Fig. 7.4  Map of the Bilbao estuary with the position of the boreholes used for the reconstruction of the Holocene evolution and localities referred to in the text. Black and white dots indicate boreholes that have been studied while grey dots indicate other boreholes drilled during the geological study for the Bilbao Metropolitan Subway. Dashed lines represent the original extent of Holocene estuarine domains (tidal flats, marshes, and the main channel). Light grey shading indicates urban areas. Dark grey areas indicate modern estuary and sea. (Modified from Leorri and Cearreta 2009)

Fig. 7.5  Scanning electron microscope images of foraminiferal tests (shells) of six different species found in Bilbao estuarine sediments (each test is roughly 150 microns across or a tenth of the size of a pin head). (Modified from Leorri and Cearreta 2009)

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Fig. 7.6  Two surface sediment sampling sites in the middle reaches of the Bilbao estuary. (Images by E. Leorri)

not describe everything that is involved in the sampling process. What is missing is a description of the difficulty and complexity of moving across these intertidal sediments. They are soft muds and sands with large amounts of organic matter and if you stand still for just a few minutes, you sink…and your rubber boots tend to get stuck once they are deep into the sediment (sorry, but we did not take the time for pictures under those circumstances). To make matters more interesting, when there is traffic in the main channel, boats and large ships can generate considerable waves. You have to dodge these while stuck up to you knees and turning around is not easy. Generally, you move forwards more easily than backwards, if you are lucky and move fast enough. Making a large circle would allow you to turn around to the

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Fig. 7.7  Recovery of PVC cores (50-cm long) in the middle reaches of the Bilbao estuary. (Image by E. Leorri)

relative safety of the concrete quay (which is quite slippery – accidents happened there!). Did I mention that you need to plan your work around the tides so you don’t suddenly find the water rising around you? This is even more fun if you are coring. The surface sediment samples provided an understanding of the modern environment (we sampled several times, seasonally and over the years). But what about the last few hundred years of history? For that, short PVC cores were necessary (Fig. 7.7). The pipes were pushed carefully into the sticky sediment to avoid downward smearing. The stickiness made recovering the cores rather daunting  – each core acted like the rubber boots that we lost. But there was another complication. Look at where the water is in relation to the cores in Figs. 7.7 and 7.8. Remember we had to account for the tides. We were forced to recover the cores very quickly before the rising tide flooded the coring site and our retreat path to solid, dry land. And I saved the best for last. These sediments are quite rich in fecal material (among other things). Yes, it means just that; we weren’t just coring mud! When you first disturb the surface of the sediment you notice the smell. Even though the smell is strong, you get used to it after a while when you are coring. At some point, your nose does not notice the smell anymore, but your stomach does. While working in the estuary, we were able to observe an interesting process that occurred quite often. As the tide rises, it brings marine water, cleaner and more oxygenated than the water at our sampling sites, up the estuary. Marine fish travel up-estuary in this marine water. When the tide falls, the marine water retreats, but leaves some pools on the intertidal sediments, where some fish are trapped. The fish cannot reach the main channel and die in front of your eyes after just a little while. It hit home – the level of pollution within the estuary.

7  The Anthropocene, Wait, What? A Basque’s Coastal Experience Helps to Figure It Out 117 Fig. 7.8  Setting up the coring equipment in the middle reaches of the Bilbao estuary for percussion coring. (Image by E. Leorri)

When we wanted to understand estuarine evolution, including anthropogenic pollution with cores longer than the 50 cm PVC cores, we turned to percussion coring. With this technique, we recovered cores 6–10  m (20–33  ft) in length (see Fig. 7.8). But remember those tides. We had to keep a very sharp eye on rising tides because the longer the core the harder it was and the longer it took to extract from the sediment (see how close the coring site is to the water in Fig. 7.8). I’m proud to say that we never left a sample site without our samples or without our equipment, or without a colleague! But we cut it close sometimes. The pictures in Fig. 7.9 show the struggle to recover a coring device. It was held tight by suction, the saturated sediment surface became unstable and, finally, the wooden platform that we had hauled out to the coring site buried itself in the sediment, tilted and broken. Eventually, this interesting situation was resolved, and we managed to struggle back to shore just a few meters away, but always keeping in our minds that tides rise really fast when you are stuck in the mud.

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Fig. 7.9  Recovery of a core after it has been inserted into the sediments. The ground became unstable making recovery of the materials very difficult while time was very limited as the tide was about to flood the site very soon! (Images by E. Leorri)

Brief Comments on the Results! Were our struggles to collect sediment cores worthwhile? What did a year or two of lab work and analysis of foraminiferal and metals data tell us? From the surface sediment samples, we know that there were high concentrations of metals in

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sediment in the late 1990s and, for the most part, the estuarine system was barren of live foraminifera, although some improvements in environmental quality were observed over time (between 1997 and 2006). Sporadic reversals in this estuarine recovery were associated with dredging of the sediments and the resulting resuspension of clay particles associated with pollutants. The percussion cores, in some cases, reached sediments with no geochemical signal of anthropogenic activities and indicated an estuarine system with large intertidal areas dominated by normal marine to brackish foraminifera and background levels of pollutants (i.e., naturally occurring concentrations). Overlying these sediments, we found the record of environmental transformation caused by the discharge of untreated domestic and industrial effluents during, at least, the last 150 years. Above that interval, there is a layer of heavily polluted sediments that is barren of foraminifera (as shown by the surface samples). The lack of foraminifera was associated with lack of oxygen and occurred during what we termed the younger industrial zone (1950–2000).

Why the Anthropocene? The Answer This chapter commenced with the question, “Why the Anthropocene?” The use of this term to reflect anthropogenic effects on our environment since the “Great Acceleration” of pollution around 1950 seems very reasonable, indeed. As I mentioned earlier, 1950 is the recommendation for the beginning of the “Anthropocene” made by the Anthropocene Working Group in 2019. However, other scholars have argued for an “early Anthropocene” that could go back to the beginning of the Industrial Revolution at ∼1800 or even to as early as a few thousands of years ago when signs of extensive agriculture (mainly rice farming) begin to show up in paleoclimate data. But we must remember that that the term “Anthropocene” does not aim to represent the fingerprint of humans globally (which varies in time according to region), but rather the time at which we became the most relevant driver of change in our surroundings. It can be understood why the term “Anthropocene” is controversial. In a recent conversation with some colleagues, they subconsciously translated the term as referring to “mankind” and others simply to “man”, thus highlighting the term’s inadequacy from a gender perspective. “Anthropos” is the Greek word for human being. Other researchers have suggested the term “Capitalocene”, which highlights capitalism’s responsibility for our planet’s climatic/environmental crisis. When to set the beginning of the Anthropocene is also controversial because human activities are recorded in the sediment significantly earlier than the mid-­ twentieth century. In the Bilbao region, I have already mentioned the regional pollution from Roman mining activities, and we have the historical evolution of the estuary and the dramatic changes occurring since at least the 1300s and more intensively as the Industrial Revolution influenced Bilbao. Clearly, human activities have impacted the environment around Bilbao for centuries if not millennia. Both natural and anthropogenic drivers have controlled the evolution of this system. Over time,

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however, human activities became more relevant and since the 1800s they have been most prominent. But the most dramatic changes occurred around the mid-twentieth century when the Bilbao estuary became unable to support life within its sediments. In my opinion, the boundary between the Pleistocene and the Holocene, which has been formally accepted, is much less pronounced in many cases than the generally dramatic change between natural and anthropogenically impacted sediments. In many coastal areas, it is impossible to recognize the boundary between the Pleistocene and Holocene, and when we do, we rely on carbon-14 dating or disruptions in the sedimentation (erosive surfaces) to identify this boundary rather than significant sedimentological markers. So, while the term “Anthropocene” may not be perfect and the timing of this epoch’s onset and definition are not yet decided, it is clear that there is a need to distinguish this period of time, whose easily recognized characteristics are controlled by a force so different from any prior interval, that is, by human beings. Acknowledgements  The works described and discussed in this chapter reflect closely Leorri and Cearreta (2009) and represent years of work by a team of researchers that are or were part of the Harea-Coastal Geology research group, led by Dr. Cearreta, although other experts contributed to these studies as well. Dr. María Jesús Irabien Gulias contribution was especially significant and clearly Dr. Alejandro Cearreta, my PhD advisor and team leader, was the person responsible for this work. Several grants funded the studies that led to this chapter: MEC121.310- 0464/96. AMB96-0464, 121.310-EA041/92, 121.310-EC221/97, 076.310-EB046/99, GIU 06/10, UNESCO06/08, GIC07/32-IT-332-07, and AE-2008-1-24. It needs to be noted that the development of the topics presented in this chapter is still ongoing and additional projects have supported this ongoing scientific adventure. I would like to thank Dr. González-Fuentes for helping me to improve this manuscript.

If You Would Like More Information Austin WJ, Holbrook JM (2012) Is the Anthropocene an issue of stratigraphy or pop culture? GSA Today 22(7):60–61 Cearreta A, Irabien MJ, Leorri E, Yusta I, Croudace IW, Cundy AB (2000) Recent anthropogenic impacts on the Bilbao estuary, northern Spain: geochemical and microfaunal evidence. Estuar Coast Shelf Sci 50:571–592 Cearreta A, Irabien MJ, Leorri E, Yusta I, Quintanilla A, Zabaleta A (2002) Environmental transformation of the Bilbao estuary, N. Spain: microfaunal and geochemical proxies in the recent sedimentary record. Mar Pollut Bull 44:487–503 Cundy AB, Croudace IW, Cearreta A, Irabien MJ (2003) Reconstructing historical trends in metal input in heavily-disturbed, contaminated estuaries: studies from Bilbao, Southampton Water and Sicily. Appl Geochem 18:311–325 Irabien MJ, Cearreta A, Serrano H, Villasante-Marcos V (2018) Environmental regeneration processes in the Anthropocene: the Bilbao estuary case (northern Spain). Mar Pollut Bull 135:977–987 Leorri E, Cearreta A (2004) Holocene environmental development of the Bilbao estuary, northern Spain: sequence stratigraphy and foraminiferal interpretation. Mar Micropaleontol 51:75–94 Leorri E, Cearreta A (2009) El registro geológico de la transformación ambiental de la ría de Bilbao durante el Holoceno y el Antropoceno. Munibe 26:1–188

7  The Anthropocene, Wait, What? A Basque’s Coastal Experience Helps to Figure It Out 121 Leorri E, Cearreta A, Irabien MJ, Yusta I (2008) Geochemical and microfaunal proxies to assess environmental quality conditions during the recovery process of a heavily polluted estuary: the Bilbao estuary case (N. Spain). Sci Total Environ 396:12–27 Waters CN, Zalasiewicz J, Summerhayes C, Barnosky AD, Poirier C et al (2016) The Anthropocene is functionally and stratigraphically distinct from the Holocene. Science 351(6269):aad2622 Zalasiewicz J, Waters CN, Williams M, Barnosky AD, Cearreta A et  al (2015) When did the Anthropocene begin? A mid-twentieth century boundary level is stratigraphically optimal. Quat Int 383:196–203 Zalasiewicz J, Waters CN, Summerhayes CP, Wolfe AP, Barnosky AD et al (2017) The Working Group on the Anthropocene: summary of evidence and interim recommendations. Anthropocene 19:55–60

Chapter 8

A Tale of Two Hydrogeology Problems in Coastal North Carolina Alex K. Manda

Abstract  This chapter highlights two tales describing the techniques scientists use to investigate how groundwater and surface water in coastal regions are threatened by saltwater intrusion. Crop production and water supply to communities are being increasingly affected. In the first tale, researchers document how they use computer models to determine the mechanisms by which saltwater intrusion is happening beneath a barrier island in North Carolina, USA, that is popular with tourists. The second tale, also from North Carolina, details the extent to which scientists will go to understand saltwater intrusion occurring in natural and artificial channels that traverse low-lying coastal regions. Keywords  Saltwater intrusion · Groundwater · Sea-level rise · North Carolina · Barrier islands · Wind tides · Water quality · Water quantity · Salinity · Monitoring

A Threat to Coastal Living Saltwater intrusion is the process by which saline water replaces freshwater in groundwater and surface water bodies. This process may pose severe consequences for (a) potable water supplies in regions that rely on local reservoirs for freshwater supplies, and (b) the diversity and vitality of flora and fauna found in coastal freshwater systems. There are several natural and anthropogenic mechanisms by which saltwater intrusion occurs in the environment. To understand how saltwater intrusion occurs, it is first useful to appreciate how groundwater and surface water interact in coastal regions. In coastal aquifers, the interface between groundwater and surface water is not a vertical straight line. Rather, saline water juts underneath freshwater forming a A. K. Manda (*) Department of Geological Sciences, East Carolina University, Greenville, NC, USA e-mail: [email protected] © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 S. J. Culver (ed.), Troubled Waters, Springer Climate, https://doi.org/10.1007/978-3-030-52383-1_8

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wedge-like feature in the subsurface, owing to density differences between freshwater and seawater at the coast (seawater is denser than freshwater). The interface between freshwater and saltwater is neither sharp nor static. It is a diffuse zone (known as the freshwater-saltwater transition zone) where mixing between freshwater and saltwater occurs. The location of the transition zone in the subsurface depends on drivers such as sea-level, subsidence, and groundwater withdrawals. Some of these processes occur on short and intermediate timescales (days to weeks) whereas other processes occur on long timescales (months to years). An increase in sea level, and/or or land subsidence would move the transition zone further inland thereby causing saltwater intrusion. Groundwater withdrawals would reduce the flow of freshwater that counterbalances saltwater and as a result would cause saltwater to migrate further inland. The extent and magnitude of saltwater intrusion in coastal aquifers may therefore be caused by natural and/or anthropogenic drivers. Surface water bodies are also threatened by saltwater intrusion. Sea-level rise and wind-tides are examples of drivers that may push saltwater into fresh surface water bodies. The saltwater in these bodies may then infiltrate into adjacent aquifers thereby making groundwater more saline. Studying and mitigating the effects of saltwater intrusion therefore depends on the causal mechanism (e.g., sea-level rise vs. groundwater withdrawals) as well as the type of water body affected by intrusion (i.e., groundwater vs. surface water). My research interests focus on investigating saltwater intrusion drivers in both surface water and groundwater in coastal North Carolina.

 ale 1: Saltwater Intrusion into Groundwater on a North T Carolina Barrier Island A recent project that my research team and I undertook involved using groundwater modeling techniques to understand how groundwater withdrawals were causing saltwater intrusion in a limestone aquifer beneath Bogue Banks, NC (Fig. 8.1). The Castle Hayne aquifer is the source of domestic water supply for thousands of permanent residents on the island and tens of thousands of holiday makers that frequent Bogue Banks during the summer. The threat from saltwater contamination is therefore taken very seriously by water managers on the island because any loss of freshwater resources would cause significant impact to the emotional and economic well-being of island residents. Coastal communities that are threatened by saltwater intrusion usually resort to finding new freshwater sources (e.g., exploiting other aquifers or surface water bodies, piping water from other areas) or desalinizing saltwater to make it potable. All of these options are very costly and take significant amounts of time and resources to develop. Our project on Bogue Banks was of interest because saltwater intrusion was occurring on the western part of the island where intrusion was least expected. Logic suggests that intrusion should occur closest to the source of salty water (the

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Fig. 8.1  Map of northeastern North Carolina, USA showing locations mentioned in the text. The yellow star indicates Bogue Banks, the location of Tale 1. The red star indicates the Emily and Richardson Preyer Buckridge Coastal Reserve, the site of Tale 2

Atlantic Ocean) but it was occurring on the western side of the island adjacent to Bogue Sound. Since it is very difficult, if not impossible to collect adequate data to characterize saltwater intrusion in deep aquifers, researchers typically use mathematical models to simulate the flow of groundwater and saltwater in the subsurface. Mathematical models that simulate groundwater flow are based on principles of physics governing the flow of water in permeable materials. As such, these models require input parameters that capture the physical and hydrologic properties of freshwater aquifers to run. We acquired geological data (rock types, thicknesses of rock units, orientations of rock units, properties of rock units, etc.) from the published literature and the State, and water level data from the local water purveyor, to create a model of the groundwater flow regime beneath the island. Using commercially available computer software, we built a rendering of the system beneath the island complete with appropriate orientations and thicknesses, physical properties and flow characteristics of layers of rock and sediment in the subsurface. This process is iterative in that we build the model and then refine it based on how well the model results match the groundwater data that were collected by the water purveyor. If the model results do not match the purveyor’s data, we adjust the parameters within reasonable limits and re-run the model to generate a new set of model results. This process is called calibration. Once the model is calibrated, that is, when the water levels generated by the model are well aligned with the water levels collected in the field, we move on to running the simulation to test our hypothesis.

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For this study, we hypothesized that paleochannels (very old stream valleys that were now filled with sediment), were the mode by which saltwater was entering the aquifer. To test this hypothesis, we included a palaeochannel in the model. We also inserted groundwater pumping wells in the model to simulate the effect of withdrawing water on the groundwater flow patterns around the paleochannel. These model wells were set to withdraw water at the same schedule and rate as those in the real world. Using this approach, we were able to determine that the saltwater intrusion observed on the western side of the island could have come from paleochannels. This information is useful for formulating strategies that may be employed to mitigate, or adapt to, the effects of saltwater intrusion in coastal aquifers. For example, water managers could opt to abandon groundwater wells, find other sources of freshwater (e.g., deeper groundwater or surface water), or develop reverse osmosis plants to meet the freshwater needs of coastal communities. The results of this study indicate that groundwater pumping in coastal regions can drive saltwater intrusion through paleochannels that are more permeable than the surrounding sedimentary units. The saltwater can then make its way to wells that provide potable water supplies, thereby threatening the potable water supplies for coastal communities that rely on groundwater. A knowledge of the existence and extent of paleochannels in coastal regions that draw water from subsurface sources could help water managers anticipate potential impacts of pumping induced saltwater intrusion on fresh groundwater sources.

 ale 2: Saltwater Intrusion in a Surface Water Body T of the “Inner Banks” of North Carolina On the landward (western) side of the broad expanse of Pamlico Sound (Fig. 8.1) is what has become known as North Carolina’s “Inner Banks”. In reality these are very low-lying lands, usually with an elevation of less than 1 m above sea level (Fig. 8.2), that look nothing like the famed, sandy Outer Banks on the seaward side of Pamlico Sound (Fig. 8.3). Several years ago, we investigated saltwater intrusion in a coastal wetland system of the “Inner Banks”. In this region, saltwater intrusion is inundating low-lying lands that are used for agriculture and conservation purposes. Since certain types of vegetation are not tolerant to saltwater, any increase in saltwater content may seriously impact the health of this vegetation. For example, in the Emily and Richardson Preyer Buckridge Coastal Reserve (Fig.  8.1), various tree stands of Atlantic White Cedar are showing signs of stress, potentially due to saltwater intrusion. According to the North Carolina Forest Service, the state of North Carolina has the largest acreage of Atlantic White Cedar in the US. Thus, any loss of Atlantic White Cedar will have severe consequences on the ecosystems in which these trees are found. In other low-lying areas, saltwater is finding its way into agricultural fields thereby preventing the growth and maturity of certain types of crops (e.g., soybeans, corn, etc.) that are important for the economic well-being of many coastal

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Fig. 8.2  A typical view of the “Inner Banks” of eastern North Carolinsa where the land is usually less than a meter above sea level. The water body shown here is Pamlico Sound. (Image by A. Manda)

Fig. 8.3  A typical view of the developed Outer Banks barrier islands with an artificial sand dune and a hotel being undercut by the Atlantic Ocean. (Image by A. Manda)

communities. Saltwater intrusion therefore threatens to decrease the yields of important cash crops. To adapt to these environmental changes, farmers might have to find alternate crops to grow, perhaps apply gypsum to their fields, or abandon their farms altogether. Some of these courses of action come at great cost, and thus are likely to cause farmers many sleepless nights. Determining the course of action

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depends greatly on the mode of saltwater intrusion, as well as the extent of the problem. Research investigations are therefore designed to shed light on the mode and extent of saltwater intrusion. There are several ideas (working hypotheses) that can explain the source of the saltwater. One idea is that the saltwater is migrating inland from the ocean and sounds due to sea-level rise. As the sea rises, ocean water would not only move further inland, but the saltwater wedge beneath the coast would also migrate inland. Although this movement would lead to saltwater sources being near agricultural fields, the process would take years to mature because the rate of relative sea-level rise is on the order of several millimeters per year in eastern North Carolina (see the Kemp and Horton chapter). Another hypothesis that may explain aquifer/soil salinization is that saltwater intrusion is driven by overwash and storm surge from tropical cyclone activity. Under this process, there is an instantaneous injection of saltwater in inundated fields that then persists in the soil or groundwater for a very long time. Wind tide events are another mechanism by which saltwater can make its way from surface water bodies to agricultural fields. These wind tides may cause the water in channels to overflow into agricultural fields. The wind tides may also prolong the presence of salts adjacent to agricultural fields so that saltwater would then have sufficient time to permeate into adjoining fields, thereby contaminating cropland. Land subsidence may also cause saltwater intrusion by lowering the land that is adjacent to the sounds or ocean. The impact of this process is that the ocean/sound level would appear to rise relative to the land surface. As a consequence, the ocean would move inland and the saltwater wedge in the subsurface would move inland. Processes that may cause land subsidence in eastern North Carolina may include groundwater pumping from coastal aquifers in southern Virginia (Fig. 8.1), or the lowering of the land surface as the Earth’s crust continues to relax due to the melting of an ice sheet in southern Canada/northern US that occurred about  15,000 to 10,000 years ago. For this study, we deployed devices (known as loggers) that autonomously record water levels and specific conductivity (used here as a proxy for salinity) in surface water and groundwater bodies (Fig. 8.4). The idea of the deployment scheme was to place the loggers in such a way that we could capture the height and the conductivity of the water from a potential source (a large human-made canal – the Alligator-­ Pungo River canal), along a river channel (the Alligator River, adjacent to the Reserve; Fig. 8.1), to finally, a series of small canals in a protected coastal reserve (Fig.  8.5). The hypothesis that we were testing for this study was that the saline water detected in the coastal reserve originated from the large constructed canal. The saline water then made its way to the reserve via the Alligator River and small canals. We further hypothesized that the driver for this movement was wind tides. To fully test these hypotheses, we collected weather data in addition to the water quality data and water quantity data.

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Fig. 8.4  Specific conductivity (left) and water level (right) loggers that are installed in wells. (Image by A. Guiliano)

Fig. 8.5  The author and research team members looking for sites to install water quality monitoring stations on the Alligator River, “Inner Banks”, NC. (Image by A. Guiliano)

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An Exciting Interlude Installing monitoring wells, deploying loggers and collecting data in the reserve and surface water bodies was an adventure unto itself. To understand the interactions between the surface water and groundwater regimes, my research team has installed and instrumented shallow groundwater monitoring stations (i.e., wells deployed in groundwater and surface water) in various locations in the Emily and Richardson Preyer Buckridge Coastal Reserve (Figs. 8.1, 8.6, and 8.7). These stations are visited periodically to measure or collect water quantity and water quality parameters in the various water bodies (Fig. 8.8). On one occasion, we needed to retrieve some data for analysis. Since the Reserve is far from Greenville, the location of East Carolina University (Fig. 8.1), and is in a very remote area with plenty of wild animals such as black bear, various snakes, alligators, and deer, I needed a field assistant to accompany me to the field site. On the day of the field excursion, my field assistant (whom I will call “Katie”) and I, planned to spend the whole day at the Reserve to give us enough time to visit all of our well sites. Early on the morning of the trip, we set about hitching a trailer with an all-terrain vehicle (ATV) to one of my department’s field trucks. We were to use the two-seater ATV to transport ourselves and equipment to the field sites that were on dirt roads far from the main road leading to the reserve. These dirt roads typically have canals on one or both sides and may have downed trees or mud holes that make travel difficult particularly after precipitation events. We got to the field site quite early and were soon at work collecting data from the wells in the northern part of the Reserve. We completed the work in time for lunch which we had at a pier overlooking the Alligator River (Fig. 8.9). Since we did not want to put the ATV back in the trailer as we relocated to the southern section of the reserve, we decided to each drive one of the vehicles: I would drive the ATV, and Katie would drive the truck and trailer. Katie did not know the way to the entrance to the southern part of the reserve, so I took the lead on the ATV while Katie followed behind me. In a few minutes we were at the intersection of the road leading

Fig. 8.6  Research team members installing monitoring wells in the Emily and Richardson Preyer Buckridge Coastal Reserve, “Inner Banks”, NC. (Images by A. Guiliano and A. Manda)

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Fig. 8.7  Installing monitoring wells across a small canal in the Emily and Richardson Preyer Buckridge Coastal Reserve, “Inner Banks”, NC. (Image by A. Guiliano and A. Manda)

Fig. 8.8 Retrieving loggers for download from monitoring wells in the Emily and Richardson Preyer Buckridge Coastal Reserve, “Inner Banks”, NC. (Image by A. Guiliano)

to the southern sites and the main road. We decided to leave the truck at the intersection so that we could both get on the ATV to get to the field sites. I beckoned Katie to park behind me, but to my astonishment she decided to drive the truck and trailer across a muddy, soggy shoulder and straight into a ditch! By the time I realized what Katie was doing, it was too late. The truck and trailer were stuck!

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Fig. 8.9  Lunch break on a pier overlooking the Alligator River, “Inner Banks”, NC. (Image by A. Manda)

I got off my ATV to survey the situation. The truck and trailer were truly stuck. I asked Katie to pull forward, to no avail. I asked Katie to pull backwards, no luck either. At this stage, we were left with no choice but to temporarily abandon our fieldwork to seek help from local residents to help pull us out. We drove the ATV to the nearest house where we were directed to another house where guys with a truck and chains could help tow us out. As luck would have it, we found the right people to help us out of our predicament. Two young men got in their vehicle and came to the truck to help us out the ditch. In just a few minutes, the truck was extricated and the two helpful young men were on their merry way. At this point, it was almost dusk and Katie assumed that we would be heading back home without the other data from the southern part of the Reserve. Katie was mistaken! We jumped onto the ATV and started off for the remaining well sites (Fig. 8.10). A few minutes down the dirt road into the reserve, Katie pointed at something moving along the road in the distance. “I think it is a bear”, I said. “A bear?! But we don’t have any protection!” Katie protested. “The ATV is sufficient protection”, I answered, “As long as we are driving and are on the ATV, we should be fine – on to the field sites!” Sure enough, it was a bear that we saw. As we approached, it started running towards us on the narrow road. I responded by stepping on the gas! “The bear is playing chicken with us”, I said, “and we are not going to blink!”

We raced towards each other and I started to sweat. About 30 feet (9 m) away from the ATV, the bear leapt into the canal next to the road! We continued on to our sites, seeing many bears of different sizes frolicking and playing on the dirt road. I have never seen so many bears in my life. In fact, in all my years working at the reserve,

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Fig. 8.10  A graduate student on an ATV with supplies for installing a monitoring well. This is a typical road in the Emily and Richardson Preyer Buckridge Coastal Reserve, “Inner Banks”, NC. (Image by A. Manda)

the total number of bear sightings at the reserve was only two! We quickly proceeded to the last well sites where I collected my valuable data and then started back to the truck and trailer. By the time that we got back to the truck, it was dark. With data from the groundwater wells in hand, we loaded the ATV into the trailer, and started off back to Greenville. Katie was very glad we were in the truck heading back to civilization. I was just glad we got to collect all the data that we needed for us to test the hypotheses for this particular study.

Back to Tale 2 The results of our study confirmed our original hypothesis that the driver of saline water into the wetlands of the Emily and Richardson Preyer Coastal Buckridge Reserve was wind tides, and indicated that the source of the saltwater intrusion was the large constructed canal. Subsequent study identified the Pamlico Sound as the main source of the saltwater. Since the region is protected from the ocean by almost uninterrupted barrier islands, astronomical tides have little influence on the daily water fluctuations in the region. Thus, wind tides were the major drivers of saltwater in the region. So, when the wind blows hard from the south, saltwater from the Pamlico Sound is pushed up the Pamlico River, through the Pungo River, along the Alligator-Pungo River canal, and ultimately to the Alligator River where any adjoining canals are overrun by saltwater. These are complicated processes that threaten agriculture in low-lying fields of the Inner Banks.

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Our study was located in a part of one Reserve, but saltwater intrusion into agricultural fields occurs in several low-lying coastal counties of eastern North Carolina. Farmers have been observing a phenomenon where patches of their agricultural fields display stressed/unhealthy crops, or in extreme cases, where patches of bare ground take over vegetated swaths of cropland. The phenomenon has been observed on farms with corn, soybeans, wheat and other cash crops. Tests of the soils in these farmlands have indicated that the soils have high concentrations of salts that inhibit the healthy growth of plants. The burning questions on the farmers’ minds are where are these salts coming from, will the problem become bigger with time, and what can be done to solve this problem? These are important considerations because the answers to these questions will help us determine the future impact of saltwater intrusion on farmers’ livelihoods. Working in collaboration with farmers, and state and county agricultural agents, my research team has deployed different types of instruments in several fields to try and provide answers to the farmers’ questions. Our suite of instruments is focused on recording the weather, water quality, and quantity. Thus, we have deployed a weather station to record air temperature, precipitation, wind direction, and wind speed at each field site. We have installed clusters of shallow groundwater monitoring wells to help us measure and record water levels and salinity in the groundwater system. And we are using automated water level and salinity loggers to record water quantity and quality measurements every 10 min. We have also deployed water level and salinity loggers to record water levels and salinity in creeks, canals and the Albemarle Sound. In addition to recording water quality and quantity in groundwater/surface water, we are monitoring soil moisture content, soil temperature and soil conductivity to investigate processes that may lead to soil salinization. We have also applied non-­ invasive techniques to image the subsurface through the use of geophysical techniques on impacted field sites. The geophysical techniques, that include direct current electrical resistivity, capacitively coupled resistivity, and ground penetrating radar, are useful for characterizing subsurface features and properties, as well as delineating the extent of saltwater plume in the subsurface. It is envisioned that the use of these techniques will help to show where the saltwater is coming from and how it is moving from the surface to the subsurface. It is likely that a combination of several of the possible processes that I described earlier are responsible for aquifer and soil salinization in eastern North Carolina. Perhaps the combination varies from place to place. Further, since some processes may have a larger influence than others, any adaptation or mitigation strategies that may be devised would have to align with the major driver of saltwater intrusion. For example, if the major driver is intermittent overwash and storm surge, then applying gypsum to agricultural fields followed by flooding with freshwater could lessen the magnitude and extent of aquifer/soil salinization. However, this process is expensive and may be impracticable if a source of freshwater is unavailable. If, however, the major driver is sea-level rise, then farmers may have to abandon their fields, or they may have to plant other crops that are more tolerant to salty soils. Our continuing project will help farmers understand the environmental changes occurring in the region so that they can better plan for their futures.

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A Finishing Thought The studies highlighted here illustrate the methods that groundwater hydrologists use to investigate saltwater intrusion in various environments and systems. There are many more techniques (e.g., geochemical, geophysical etc.) that scientists may apply in answer specific research questions concerning saltwater intrusion. Bears might not care about saltwater intrusion, but as coastal populations continue to grow, and as sea level continues to rise, saltwater intrusion problems will continue to be of major interest to humans for the foreseeable future. Understanding the drivers, mechanisms, and techniques for assessing saltwater intrusion will help in the development of appropriate adaptation and mitigation strategies to address the water resource problems that may arise. Acknowledgements  The following are thanked for providing resources, assistance, and access that enabled the research described in this article: Woody Webster (Reserve manager of the Emily and Richardson Preyer Buckridge Coastal Reserve), the staff, students and faculty in Department of Geological Sciences at East Carolina University, and the North Carolina Clean Water Management Trust Fund.

If You Would Like More Information Barlow P (2003) Ground water in freshwater-saltwater environments of the Atlantic Coast United States Geological Survey circular: 1262. USGS, Reston Manda AK, Sisco MS, Mallinson DJ, Griffin MT (2015) Relative role and extent of marine and groundwater inundation on a dune-dominated barrier island under sea-level rise scenarios. Hydrol Process 29:1894–1904 Manda AK, Reyes E, Pitt J (2018) In situ measurements of wind-driven salt fluxes through constructed channels in a coastal wetland ecosystem. Hydrol Process 32:636–643 Manda AK, Giuliano AS, Allen T (2014) Influence of artificial channels on the source and extent of saline water intrusion in the wind-tide dominated wetlands of the southern Albemarle Estuarine System, (USA). Environ Earth Sci J 71:4409–4419 Masterson JP (2004) Simulated interaction between freshwater and saltwater and effects of ground-water pumping and sea-level change, Lower Cape cod aquifer system, Massachusetts. United States Geological Survey Scientific Investigations Report 2004–5014. U.S. Geological Survey, Cape Cod Mulligan A, Evans R, Lizarralde D (2007) The role of paleochannels in groundwater/seawater exchange. J Hydrogeol 335:313–329

Chapter 9

Drilling the North Carolina Coastal Plain – Discovering What Lies Beneath Kathleen M. Farrell

Abstract  This chapter explains how geologic environments of the Quaternary are explored by a field geologist who drills holes and collects core samples from the coastal plain of North Carolina, USA, and why these cores are windows into the sedimentary rock pile that lies beneath our Earth’s surface. It is the tale of one geologist who maps landforms and cores for stratigraphy not only because it’s so much fun, but also because society can benefit from the research findings—usually in the form of geologic maps and cross sections constructed from cores. Maps and cross sections can help us to identify surface water pathways and underground flowpaths, the size and scale of underground reservoirs and aquifers, and the distribution of economically valuable minerals. They can also be used to develop geologic hazard and groundwater vulnerability maps, for more effective land use planning. Keywords  Coastal Plain · Stratigraphy · Geomorphology · Coastal geology · Geologic coring · Quaternary · Barrier island · North Carolina · Louisiana, Georgia

 y Life as a Geologist: What It Entails, and Reasons M for Pursuing Field Geology as a Profession Although discovering and collecting fossils is of great interest to both the layperson and scientists, geologists must also describe and understand the sediments (unconsolidated gravel, sand and mud deposits) and sedimentary rocks (consolidated and hard) in which the fossils are found. This area of study is called stratigraphy—strata means layer and sedimentary rocks are layered, like a layer cake. I am a stratigrapher, a sedimentologist (study of sediment), and a geomorphologist (study of the shape of the earth’s surface, i.e., the landscape, and its landforms). I work as a Senior Geologist at the North Carolina Geological Survey (NCGS), conducting applied research on North Carolina’s Coastal Plain. My job is to divide up the K. M. Farrell (*) North Carolina Geological Survey, Raleigh, NC, USA e-mail: [email protected] © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 S. J. Culver (ed.), Troubled Waters, Springer Climate, https://doi.org/10.1007/978-3-030-52383-1_9

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landscape of the Coastal Plain into landforms, define the Quaternary (the last 2.58 million years) layers that underlie these landforms, and then group layers with similar sedimentary properties into formations, which are the fundamental units shown on geologic maps. I use two principal scientific techniques to make geologic maps of the Coastal Plain: (1) remote sensing to interpret landforms from satellite images and LiDAR elevation data, and (2) geologic core drilling to discover the rocks or sediment that underlie the landforms. LiDAR, an acronym for Light Detecting and Ranging, is an airborne surveying method, that uses laser light to collect elevation data. Remote sensing and geologic cores used together can help define rock and sediment properties across broad areas of the Coastal Plain. And geologic coring is one of the most interesting and rewarding endeavors for a working field geologist because the core itself provides a window into hundreds to thousands to millions of years of dynamic landscape evolution and Earth history that otherwise would remain invisible to us humans who inhabit the Earth’s surface. Several reasons drive us to study the stratigraphy and landforms of the North Carolina Coastal Plain. In particular, geologists need to locate water resources, find oil and gas reserves, discover economically valuable minerals and construction materials, and identify areas subject to geologic hazards. We need the cores to ground-truth the geology in areas where the underlying stratigraphy simply cannot be viewed at the Earth’s surface. The sediments and rocks beneath us provide the plumbing for fluids, such as water, oil, and gas, to move through the Earth or to be stored underground in natural holes or pore spaces. If pore spaces are connected, permeable conditions exist, and fluids can move freely along underground pathways or conduits. The size of pore space can range from very large caves that form in limestones to very small pores between individual sand grains. Limestones may include vast networks of interconnected pore space because the rock dissolved from contact with subterranean acid waters. In fact, some limestones include caves with flowing underground streams. The ~40 million year-old Castle Hayne Limestone is an example of a partly dissolved permeable limestone that functions as the main aquifer that supplies clean water for eastern North Carolina. In other Coastal Plain deposits, sands and gravels also act as aquifers, but these store and transmit water through small pores between grains. Impermeable strata such as muds and clays may act as confining units to trap water and seal it in underground aquifers. Similar geologic conditions can also trap oil and gas in underground ‘reservoirs’, that are natural underground holding tanks. Pollutants originating at the ground surface can also move downward through the geologic plumbing, mix with clean water and degrade its quality, and migrate outward through permeable strata, carrying contaminants far afield. In addition to subterranean fluids, Coastal Plain deposits may contain other economically valuable resources. Gravels, sands and limestones are useful for construction; minerals such as titanium are needed for manufacturing steel, paint and other products; and phosphorus-rich minerals are used to make fertilizer. While mapping and drilling across eastern North Carolina, I routinely encounter ancient beach deposits that contain heavy mineral sands, beds of phosphate nodules, and large amounts of sand and gravel under river terraces, that may be suitable for

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mining. To understand, predict and identify the geologic formations that act as aquifers, sources for economically valuable deposits, or pollution pathways, the geologic framework must be described. As a research geologist and field mapper at the NCGS, this is my job—to characterize the geologic framework of the Coastal Plain, to discover what lies beneath a flat, nearly featureless landscape. Another reason to study landforms and stratigraphy on the Coastal Plain is to predict areas that may be subject to geologic hazards. The main geologic hazard that impacts the Coastal Plain is flooding. Flooding is short-term and seasonal but includes coastal storm surges originating on the oceanside and migrating up rivers, riverine floods moving downstream along drainages towards the coast, and ponding water that forms temporary lakes on uplands after significant rainfall events. Flooding, of course, affects the youngest, active landforms, such as modern-day barrier islands, salt marshes, swamps, river channels and point bars, and low-lying terraces. What isn’t commonly known is that the older higher upland terraces with their subtle, natural bowl-like configurations (like New Orleans during Hurricane Katrina) may turn into lakes after significant rain fall events, causing widespread flooding of farms, homes, and communities, in areas that are not directly connected to the sea or rivers. During floods, landforms erode, and sediment is redeposited elsewhere; inlets may open or close; channels may be cut or move; stream banks may retreat; the oceanside shoreline may migrate inland. The impacts of long-term flooding caused by sea-level rise will be even more devastating, as low-lying coastal and riverine terraces that are currently dry land will be gradually inundated—permanently, on human time scales! Geologic maps based on landforms can be used for strategic planning to define potentially hazardous, unsafe areas for living, and potentially safe, stable areas that can support new economic development.

 he Location of My Geological Field Work – T The Mid-­Atlantic Coastal Plain The Coastal Plain of eastern North Carolina is the emerged, landward portion of the Atlantic continental shelf (Fig. 9.1). This landscape consists of low-relief, flat, eastward dipping marine terraces that are dissected by a series of river drainages. Its surface is underlain by a seaward-thickening wedge of Cretaceous (145–66 million years old) and Cenozoic (66 million years old to modern) rock and sediment that thins westward to a feather edge along the Fall Line, the boundary of the Coastal Plain with the adjacent, more-resistant to weathering, crystalline and metamorphic bedrock of the Piedmont Province. The Coastal Plain wedge of sediment attains a maximum known on-land thickness of about 3048  m (10,000  ft) beneath Cape Hatteras (Fig. 9.1). Offshore from the Cape, greater thicknesses of sediment have likely accumulated (7–10 km! or ~ 3–6 miles!) and underlie the offshore continental shelf and rise; it is these deeper strata that may contain petroleum resources.

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Fig. 9.1  LiDAR map of eastern North Carolina, USA, showing physiographic features mentioned in the text. (Source: K.M. Farrell)

The Coastal Plain is a relict landscape characterized by stairstep topography. This is a series of progressively younger scarps, which we know are paleoshorelines, and intervening flat terraces that step down in elevation and age towards the coast and into river basins (Fig. 9.1). A simplistic model is that the scarps are step-­ like features cut by ancient waves (such as along a beach), and the terraces were planed off by wave activity during rises and falls of sea level. In reality, the surficial deposits associated with these relict geomorphic features include a complex assemblage of marine shelf, barrier island, estuarine and fluvial deposits. Rises and falls in sea level caused by ice sheets melting or expanding over the last few million years drove the marine incursions that sculpted this landscape, controlling the geomorphic processes that formed the continental shelf and the river valleys along its margin. These are the deposits that I study as a professional field geologist.

Geologic Adventures – The Beginnings of an Obsession I am proud to be a working field geologist. Field work, drilling geologic cores and describing outcrops in quarries and along waterways are among my obsessions in life. But the reality is that as a scientist, I am driven to understand the relationship

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between the geomorphology of the Coastal Plain and the stratigraphy that underlies it, or in other words, the dynamic evolution of the Quaternary landscape. Although these concepts are always on my mind, most people that I meet, the farmers, watermen, neighbors, landowners and friends at the pub, rarely understand this obsession! Although, somewhat surprising to me, some do! My first exposure to the geologic coring of unconsolidated modern coastal deposits occurred when I was a PhD student at Louisiana State University in the 1980s. During this period, I signed up for a summer field course with coastal and planetary geologist, Dr. Dag Nummedal (who discovered the channels on Mars) and six other students. That field course consisted of cruising (by boat) around the Mississippi Delta and offshore in the Gulf of Mexico, exploring Louisiana’s wetlands, bayous, shipping channels and beaches (Fig.  9.2). We sailed through bulrushes (Fig. 9.3), crawled into shore across mud beaches that sucked us down like quicksand, stayed in remote research stations on stilts, visited a town on poles where retired seamen lived (Fig.  9.4). And everywhere, Dag brought along his gigantic vibracorer that required the seven of us to operate. A vibracorer is a gasoline-run concrete vibrator that is attached to an aluminum core tube that is vibrated into the ground to collect a core sample (Fig. 9.5). In particular, we cored Barataria Bay, a shallow interdistributary bay on the Mississippi Delta. This was my last big field expedition prior to birthing my first child; I was 5 months pregnant at the time. Interestingly, 34 years later, my daughter was married down on the bayou (Bayou Lafitte) not far from Barataria Bay. Vibracoring was

Fig. 9.2  Aerial photograph from rented twin-engine plane showing fringing beach along the Gulf of Mexico in Louisiana, and the wetlands and tidal channels, landward of the beach. (Image by K.M. Farrell)

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Fig. 9.3  The coring team in the Mississippi Delta Phragmites wetland, seeking to establish a coring site deep within the marshes. (Image by K.M. Farrell)

Fig. 9.4  View from a field boat heading into a Mississippi Delta stilt town, with a cargo of 30 ft. (9.1 m) aluminum core tubes extending beyond the bow of the boat (Image by K.M. Farrell)

exhausting but really fun, and great aerobic exercise; 30 ft. (9.1 m) long metal tubes about 3.5 inches (9 cm) in diameter were vibrated into the ground, and then pulled out, full of wet, heavy sediment, using a tripod, come-along, and cable.

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Fig. 9.5  The author and fellow student vibracoring in the margin of a water body in the Mississippi Delta. Note the three-piece vibracorer – the gasoline engine, the vibrating head, and the coil connector) being operated by the author. (Image by P. Lowry)

Meanwhile, my dissertation research at LSU, with Dag as major advisor, consisted of drilling coreholes in flood deposits of the Mississippi River near False River, Louisiana, a huge oxbow lake. Why? The usual reasons: scientific curiosity and the acquisition of knowledge. No one before me had described flood deposits from a sedimentologic and stratigraphic perspective, and I wanted to do it first. My focus area included the geologic environments—oxbow lake, backswamp, natural levees and crevasse splays, along the margin of the Mississippi River’s meander belts. One day while exploring black water marshes at the end of the oxbow lake, I saw a baby alligator and realized that I was trekking through floating marshes; alligators nest underneath the floating marshes! Later, a woman who lived on the lake’s shoreline showed me a photograph of her husband and a large group of his friends standing on the back of the largest alligator that I have ever seen. It must have been 8 ft. (2.4 m) wide and 15 ft. (4.6 m) long or more. As the story goes, it was this behemoth alligator who was the great grandfather of all the little alligators living in False River Lake. But a field scientist can’t worry about snakes and alligators when obsessed with coring in swamps. Fearlessness is essential! The last core was collected from a sugarcane field when I was 8 months pregnant, on a day when it was 110 °F (43 °C) in the shade. After completing my education, I managed to secure a position as Senior Coastal Geologist at the Georgia Geologic Survey. My job was to study the stratigraphy of the Georgia coast using, yes, geologic cores. Meanwhile, a geologist in Canada (Derald Smith) had invented a scaled-down version of Dag’s gigantic vibracorer. Because I needed to improve portability and decrease personnel needs for field operations, I set up Derald’s ultra-light vibracorer. This assembly included a 19 lb. (8.6 kg) backpack concrete vibrator, and a lightweight portable tripod (designed to rescue injured people from manholes) and resulted in a coring operation that

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Fig. 9.6  Jim Henry’s WWII landing craft refurbished for coastal research in Georgia. Note the load of 30 ft. (9.1 m) aluminum vibracore pipes (Image by K.M. Farrell)

required only two people—my assistant and myself. In spite of its downsizing, the ultra-light vibracorer could still collect 30 ft. (9.1 m) long cores in the metal tubes. Once again, I had a great time drilling the back-barrier wetlands and tidal channels of Georgia’s barrier islands. My colleague, Dr. V.J. (Jim) Henry had a World War II landing craft that he converted into a research vessel (Fig. 9.6). This carried the vibracorer and three worker bees (VJ, his post-doc, Faisal M.  Idris, and me) through tidal channels deep into the Georgia salt marshes (Fig.  9.7). Jim would anchor his landing craft and dive into the tidal channels for an afternoon swim. I would jump in and hang on to a rope tied to the boat because the tidal currents associated with 3  m (9.8  ft) diurnal tides were strong enough to sweep me away. Meanwhile, the alligators were roaring like lions. But no worries, we were collecting cores and enjoying the natural beauty of the geologic landscape. For me, field work in remote natural areas is akin to going on vacation. Onward to the North Carolina Geological Survey (NCGS) in 1991. Stationed at a Core Storage Facility to boot! A library for rocks: this to me, is Nirvana! (Fig. 9.8). Many coring operations that I participated in or observed during this period included big rigs capable of drilling deep coreholes, and, the cores were then stored in our rock library! A mud-rotary, wireline coring operation, for example, collected a 1300 ft. (400 m) long core at Kure Beach, NC. This core, collected during a project related to aquifers and water resources, penetrated a thick section of Cretaceous rocks that were deposited when dinosaurs inhabited what was to become the eastern United States 66 million years later. Another project where I participated as a collaborator with Drs. Steve Culver, Dave Mallinson and Stan Riggs of East Carolina University, and others, included cores that penetrated the Quaternary section beneath North Carolina’s Outer Banks barrier islands and the adjacent mainland (Fig. 9.9). I also drilled scores of coreholes to describe the shallow stratigraphy (