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Geophysical Phenomena and the Alexandrian Littoral N. Evelpidou, C. Repapis, C. Zerefos, H. Tzalas and C. Synolakis
Geophysical Phenomena and the Alexandrian Littoral
N. Evelpidou, C. Repapis, C. Zerefos, H. Tzalas and C. Synolakis
Archaeopress Publishing Ltd Summertown Pavilion 18-24 Middle Way Summertown Oxford OX2 7LG
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ISBN 978-1-78969-234-1 ISBN 978-1-78969-235-8 (e-Pdf)
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Contents List of figures and tables��������������������������������������������������������������������������������������������������������������iii Acknowledgements�����������������������������������������������������������������������������������������������������������������������v
Preface�������������������������������������������������������������������������������������������������������������������������������������������vii
1. Introduction�������������������������������������������������������������������������������������������������������������������������������� 1 1.1 Location and physical geography���������������������������������������������������������������������������������������������������1 1.2 Geological characteristics ����������������������������������������������������������������������������������������������������������������5 1.3 Geomorphology�������������������������������������������������������������������������������������������������������������������������������10
2. Subsidence regime������������������������������������������������������������������������������������������������������������������� 14 2.1 Bathymetry���������������������������������������������������������������������������������������������������������������������������������������14 2.2 Submerged ancient structures������������������������������������������������������������������������������������������������������16
3. Evidence of offshore subsidence in Alexandria������������������������������������������������������������������ 20 4. Palaeogeography���������������������������������������������������������������������������������������������������������������������� 29
5. Historical maps������������������������������������������������������������������������������������������������������������������������� 33
Veduta d’Alessandria Codice Urbinate 277 [1472]����������������������������������������������������������������������������34 View of Alexandria from the Portolano of Piri Reis [1513]�������������������������������������������������������36 Vray portraict de la Ville d’Alexandrie en Egypte [1547]���������������������������������������������������������38 Plan M.P.nl-XLIX-43 of Alexandria from the Archivos General de Simancas [1605]�������������40 Alexandria, Vetustissimum Aegypti Emporium [1619]�������������������������������������������������������������������42 View of Alexandria by Vassili Barkij [1730]���������������������������������������������������������������������������������43 Description de la ville d’Alexandrie, telle qu’elle étoit du terms de Strabon, par M. Bonamy [1731]��46 Carte et Plan du Port Neuf d’Alexandrie by Capt. Frederick Lewis Norden [1738] and Carte particulière de la Vielle et de la nouvelle Alexandrie et de ses Ports [1738]��������������������������������������48 Konstantin of Kiev ‘Θέα του λιμένος της Αλεξανδρείας’ [1795]����������������������������������������������49 Konstantin of Kiev ‘Χάρτα της Άλεξανδρίας και των δύω αυτής λιμένων’ [1795]���������������49 Carte générale des côtes, rades, ports, ville et environs d’Alexandrie dressée par M. Gratien le Père [1798]�������������������������������������������������������������������������������������������������������������������������������������������������53 Plan of the city harbours and environs of Alexandria, by Captain Smyth (1825)�����������������54 Plan d’Alexandrie par Mahmoud Bey el Falaki [1866]������������������������������������������������������������������56
6. Historical references��������������������������������������������������������������������������������������������������������������� 62
7. The decline of Alexandria and physical disaster���������������������������������������������������������������� 66 8. Modelling tsunami vulnerability������������������������������������������������������������������������������������������� 71 8.1 Simulating possible tsunamis in Alexandria�������������������������������������������������������������������������������72 8.2 Scenario megathrust tsunami sources ���������������������������������������������������������������������������������������73 8.3 Tsunami simulation results������������������������������������������������������������������������������������������������������������74 8.4 Tsunami impacts at Alexandria�����������������������������������������������������������������������������������������������������75
9. Coastal zone ����������������������������������������������������������������������������������������������������������������������������� 78
9.1 Silsileh�����������������������������������������������������������������������������������������������������������������������������������������������78 i
9.2 Chatby �����������������������������������������������������������������������������������������������������������������������������������������78 9.3 Ibrahimia ������������������������������������������������������������������������������������������������������������������������������������82 9.4 Sporting Beach ��������������������������������������������������������������������������������������������������������������������������83 9.5 Moustafa Kamel�������������������������������������������������������������������������������������������������������������������������85 9.6 Gleemenopoulos Beach�������������������������������������������������������������������������������������������������������������85 9.7 Sidi Bishr�������������������������������������������������������������������������������������������������������������������������������������85 9.8 Miami Island – Gezira Gabal el Khour (Gabr el Khour)��������������������������������������������������������86 9.9 Montazah �����������������������������������������������������������������������������������������������������������������������������������86 9.10 Maamourah ������������������������������������������������������������������������������������������������������������������������������87 9.11 Abou Kir ������������������������������������������������������������������������������������������������������������������������������������87 9.12 Nelson’s Island (Abou Kir Island)������������������������������������������������������������������������������������������88
10. Fish tanks�������������������������������������������������������������������������������������������������������������������������� 89
10.1 Fish tanks in Alexandria���������������������������������������������������������������������������������������������������������90 10.2 Fish tank findings��������������������������������������������������������������������������������������������������������������������92 10.2.1 Montazah fish tanks�������������������������������������������������������������������������������������������������������93 10.2.2 Abou Kir fish tank�����������������������������������������������������������������������������������������������������������98 10.2.3 Miami Island fish tank�������������������������������������������������������������������������������������������������104 10.3 Main sea level indicators������������������������������������������������������������������������������������������������������112 10.3.1 Protective moles�����������������������������������������������������������������������������������������������������������112 10.3.2 Upper walkway (upper crepidine)�������������������������������������������������������������������������������113 10.3.3 Lower crepidines�������������������������������������������������������������������������������������������������������������113 10.3.4 Closing gates (cataractae)���������������������������������������������������������������������������������������������113 10.3.5 Channels�������������������������������������������������������������������������������������������������������������������������114 10.4 Relative sea level changes and Alexandria’s fish tanks���������������������������������������������������114
References����������������������������������������������������������������������������������������������������������������������������� 117
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List of figures and tables Figure 1a: Site map of coastal Alexandria.����������������������������������������������������������������������������������������������������������� 2 Figure 1b: Sites with valuable geomorphological and archaeological features in the Alexandrian coastal zone.�������������������������������������������������������������������������������������������������������������������� 4 Figure 2: Long-term average Holocene rates of subsidence along the Nile Delta based on stratigraphic analyses of radiocarbon-dated core data (after Stanley and Warne 1998). Sites: A: East Harbour, B: East Canopus, C: Herakleion, D: NW Burullus lagoon, E: SE Burullus lagoon, F: Tell Tinis and G: Pelusium.�������������������������������������������������������������������������������������������������������������������������� 7 Figure 3: The major fault zones of the wider Alexandria area (Zaghloul et al. 2001).��������������������������������� 8 Figure 4: Bathymetric maps of the East Harbour of Alexandria, based on historical maps dating from the end of the 18th to the beginning of the 20th century AD.����������������������������������������������������� 15 Figure 5: Comparison of bathymetric profiles between Le Diamant–El Hassan, in 1833 and 1920, lead to the suggestion of subsidence in the sea floor of >1.5 m����������������������������������������������������������� 16 Figure 6: Cumulative diagram of earthquakes and tsunamis occurring in Alexandria over the past 2000 years (Goiran 2001; Chalari 2007).������������������������������������������������������������������������������������������� 19 Figure 7: The map of the Codex Urbinate 277 (1472), depicting the present 12 reefs as protruding features.������������������������������������������������������������������������������������������������������������������������������������������������ 21 Figure 8: Le Diamant, depicted above sea level (Panchoucke 1821-9).�������������������������������������������������������� 22 Figure 9: Age calibration provided an age of 1735–1806 AD (95.4% probability) for the timber sample dated by the Oxford Radiocarbon Accelerator Unit.��������������������������������������������������������������������� 24 Figure 10: Age calibration provided an age of 1719–1780 AD (95.4% probability) for the same sample dated using the Klaus-Tschira-Labor für Physikalische Altersbestimmung, Curt-EngelhornZentrum Archaeometrie gGmbH, Mannheim, Germany, in cooperation with the Dimokritos Research Centre, Athens.������������������������������������������������������������������������������������������������������������������� 24 Figure 11: A piece of timber from a wrecked ship found at El Hassan reef at a depth of 10 m.���������������� 25 Figure 12: Sketch of the ship, impact location, and a detailed design of the ship’s bottom.��������������������� 27 Figure 13: Veduta d’Alessandria, Codice Urbinate 277, 1472 (Jondet, Pl. I).���������������������������������������������������� 35 Figure 14: Jean-Louis Bacque-Grammont, Michel Turchscherer, Piri Reis – Evliya Celebi, Deux regards ottomans sur Alexandrie, Centre d’Etudes Alexandrines, Alexandria 2013.��������������������������������������� 37 Figure 16: Harry E. Tzalas, The two ports of Alexandria, Plans and maps from the 14th century to the time of Mohamed Ali, Underwater archaeology and coastal management, Focus on Alexandria: 21–22. UNESCO Publishing, Paris, 2000. ������������������������������������������������������������������������������������������ 41 Figure 17: Alexandria, Vetustissimum Aegypti Emporium, 1619.�������������������������������������������������������������������������� 44 Figure 18: The wanderings of Vassili Grigorovich-Barskii to the Holy Places of the East from 1723 to 1747. Published by the Orthodox Palestine Society after a genuine manuscript prepared by Nikolai Barsukov, St Petersburg 1886–1887; see also Τόπος και Εικόνα, χαρακτικά ξένων περιηγητών για την Ελλάδα, 18ος αιώνας, Olkos, Athens, 1979.����������������������������������������������������������������������������������� 45 Figure 19: M. de Bonamy, Mémoire, Description de la ville d’Alexandrie, telle qu’elle étoit du tems de Strabon, Paris, 31.8.1731.�������������������������������������������������������������������������������������������������������������������� 47 Figure 22: Frederick Lewis Norden, Travels in Egypt and Nubia, London 1757; Jondet, Pl. XII; Konstantin, Ancient Alexandria, Description of the town during the visit of Archimandrite Konstantin, published in Moscow (1803) ‘at the expense of the well-known Greek Maecenas, the Zosima brothers’. ���������������������������������������������������������������������������������������������������������������������������������������������������������������� 50 Figure 20: Carte et Plan du Port Neuf d’Alexandrie by Capt. Frederick Lewis Norden [1738] and Carte particuliere de la Vielle et de la nouvelle Alexandrie et de ses Ports [1738]. ���������������������������������������� 50 Figure 21: Konstantin of Kiev, Θέα του λιμένος της Αλεξανδρείας, 1795. �������������������������������������������������������� 51 Figure 22: Frederick Lewis Norden, Travels in Egypt and Nubia, London 1757; Jondet, Pl. XII.; Konstantin, Ancient Alexandria, Description of the town during the visit of Archimandrite Konstantin, published in Moscow (1803) ‘at the expense of the well-known Greek Maecenas, the Zosima brothers’.���������������������������������������������������������������������������������������������������������������������������������������������� 52 Figure 23: Jondet, Pl. XVII. There are two other maps of Alexandria and its wider area created by the Bonaparte Expedition: Carte des Cheneaux d’Accès au Port d’Alexandrie, 1798, Jondet Pl. XIX and Carte d’Alexandrie et de ses environs d’Agamy à Aboukir, 1798, Jondet Pl. XVIII.���������������������������� 55 Figure 24: Plan of the city harbours and environs of Alexandria, by Captain Smyth (1825).�������������������� 57
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Figure 25: Mahmoud Bey, Mémoire sur l’Antique Alexandrie ses faubourgs et environs, Copenhague, 1872.� 58 Figure 26: Alexandrie ancienne par Neroutsos Bey (1888)��������������������������������������������������������������������������������� 61 Figure 27: Map of the East Harbour of Alexandria showing archaeological sites (based on Goddio et al. 1998). ���������������������������������������������������������������������������������������������������������������������������������������������������� 63 Figure 28: Plots of the wave height in relation to time that would be observed a) in the area of Pharos, and b) off the coast of Alexandria.���������������������������������������������������������������������������������������������������� 75 Figure 29: Plots of the wave height in relation to time that would be observed a) in the area of Pharos, and b) off the coast of Alexandria. (Nikos Kalligeris, private communication). For reference, we reproduce here the graph by Shaw et al. (2008) of the wave height against time in the area of Pharos, by the AD 365 earthquake. ��������������������������������������������������������������������������������������������� 77 Figure 30: A section of the gateway and tower.������������������������������������������������������������������������������������������������� 80 Figure 31: Traces of the submerged semi-circular and ‘Π’ formation at Chatby from French satellite image, courtesy of the Centre d’ Etudes Alexandrine.������������������������������������������������������������������ 81 Figure 32: The Sporting coast and submerged structures (photo: The Greek Mission).���������������������������� 83 Figure 33: Underwater ancient remains at Sporting (photos: The Greek Mission).������������������������������������ 84 Figure 34: The area under study and evidence of possible fish tanks in the littoral region of the east end of the Maamourah Gulf to Abou Kir promontory.�������������������������������������������������������������������������� 90 Figure 35: The Montazah fish tank consists of four main parts, each divided into many smaller tanks linked with each other through channels or arches.��������������������������������������������������������������������� 94 Figure 36: The cut, outer walls of the Montazah fish tank stand higher than the inner ones to protect the tank from the storms.������������������������������������������������������������������������������������������������������������������������� 95 Figure 37: Short channels connect the tanks and distribute the water, ensuring adequate circulation within the fish tank.���������������������������������������������������������������������������������������������������������������������������� 96 Figure 38: A) Channel C in the Montazah fish tank; B) its sliding grooves (Cs) cut into the stones used for the fitting of sluice gates.������������������������������������������������������������������������������������������������������������������� 97 Figure 39: The western part of the Montazah fish tank is the largest, but with fewer smaller tanks (or possibly the partitions have not survived).������������������������������������������������������������������������������ 97 Figure 40: Submerged tidal notch at -24 cm found at the western part of the Montazah fish tank.������� 98 Figure 41: Τhe eastern part of the Montazah fish tank is the most complex, with many divisions within the main tank. In this part was found a channel for fresh water input from inland to the tank.���� 99 Figure 42: The Abou Kir fish tank, a simple, gamma-shaped construction.����������������������������������������������� 100 Figure 43: The outer defensive wall of the Abou Kir fish tank.�������������������������������������������������������������������� 101 Figure 44: The lower crepidine in the Abou Kir fish tank, found at -93 cm.���������������������������������������������� 102 Figure 45: The Abou Kir area, according to Breccia (1926), included several fish tanks (based on Bartocci 1925). �������������������������������������������������������������������������������������������������������������������������������������������������� 102 Figure 46: (A) FT2 fish tank (see Figure 30) as seen on Google Earth in a satellite image of 2004, which (B) is described by Jacono (1924) and compared with Castello Del Sangallo in Italy.������������������� 103 Figure 46C: A photograph of the fish tank at Abou Kir as described by Breccia (1926).����������������������������� 104 Figure 47: The Miami Island fish tank.������������������������������������������������������������������������������������������������������������� 105 Figure 48: The Miami Island fish tank, a complex and sophisticated construction, is carved in the southeastern region of the homonymous island. To the left is a narrow tank dug into the rock (A), which we assume was constructed to provide some shade for the fish during the day. Channels may also be noticed for the renewal of the tank’s water supply from the open sea (B).�������������������������������������������������������������������������������������������������������������������������������������������������������� 106 Figure 49: The crepidine in the Miami Island fish tank.�������������������������������������������������������������������������������� 106 Figure 50: The main channel cut around Miami Ιsland.�������������������������������������������������������������������������������� 107 Figure 51: RSL curves for the site of Montazah, obtained solving sea level equations numerically. GIA models ICE-6G (VM5a) (solid) and ANU (dashed) have been used for the two different time Figure 50: The main channel cut around Miami Ιsland.���������������������������������������������������������������������������������� 107 Table 1: Table 2:
Fish tanks identified and discussed in the text, with their geographical coordinates������������ 91 Measurements from on the fish tanks studied and architectural characteristics������������������ 106
iv
Acknowledgements For the last seventeen years, the Hellenic Institute of Ancient and Medieval Alexandrian Studies (HIAMAS), under the leadership of the historian H. Tzalas, and in collaboration with the Department of Underwater Antiquities of the Supreme Council of Antiquities of Egypt in Alexandria and the Mariolopoulos-Kanaginis Foundation for the Environmental Sciences, have conducted twenty-nine campaigns of underwater archaeological and geophysical surveys along the Alexandrine littoral. Countless teams of divers, historians, archaeologists and geologists were involved in these missions, and the findings are presented in a series of HIAMAS reports (1–29). The present authors also wish to thank Professor Phillip England for his constructive comments related to the submergence of the El Hassan reef.
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Preface The study of Alexandria’s historical geomorphological changes that occurred on its littoral coasts is a fairly new subject of investigation and research. Over its long history Alexandria has been subjected to recurrent natural forces of destruction, such as earthquakes and tsunamis. These forces were responsible for the disappearance of its great monuments of antiquity and the eclipse of its great civilization. While such natural phenomena have left their mark, such as the soil subslides of the city’s littoral coasts, they continue to bring changes with rising sea levels and the erosion of its coasts. Hence comes the importance of such studies in tracing back the past implications of such natural phenomena on the city, while also trying to access and guide the future safeguarding and conservation of its littoral environment. Historically, man looked helplessly at the natural forces of destruction with fatalism, investing them with some superpower or interpreting them as the acts of some obscure god, reverting to mystic legend and religious revelation to safeguard and protect him from whatever threatened his existence and welfare. Maat in ancient Egyptian polytheistic religion represented balance in the cosmic order. Isfat represented the exact opposite, imbalance and disorder. Egyptians feared the drought of the Nile and its disastrous inundations, and so they conducted sacrifices at the Nile festivities (Wafa’a El Nil). Similarly, Zeus the thunder god was worshipped in Greek mythology. Nature deities were therefore symbolically in charge of its forces in our ancient civilizations. Ancient philosophical thought and reason brought other legendary approaches, attempting to deal with the issue of natural destructive phenomena. The most symbolic legend comes in Plato’s Timaeus in 335 BC as Atlantis, the lost continent. Atlantis was vii
believed to be a scientifically advanced and marvelous city; it was destroyed, buried and sank in the deep sea. Plato’s student Aristotle remarked that Plato was trying to make a point, but Aristotle’s writings on the subject did not clarify the mystery. Aristotle’s connection with Alexander the Great is well known. Did the tutor bring the legend to the attention of his student? Was the destiny of Alexandria in any way connected to the legend of Atlantis? Atlantis is believed to have existed on the marshes of Dona Island in Spain when a number of earthquakes and tsunamis swept the area, destroying the city of Tartessos. Another location for Atlantis was suggested to have been closer to Plato’s homeland Crete in Greece, referring to its great Minoan civilization 1500 BC, which was abruptly destroyed by the Santorinas volcano eruption, earthquake and tsunami. Their effects and consequences were felt on the shores of the Mediterranean including Egypt’s. Plato’s calculations on the location of Atlantis and its time is suggested by Galanopoulos to have had an error of translation, adding an extra zero to his figures, (900 instead of 9000 and 250 instead of 2500 miles), implying a more likely proximity and connection between Crete and the Egyptian littoral coast.1 Heracleon, east of Abu Kir on the Egyptian Mediterranean littoral, also destroyed by an earthquake and sunken by a tsunami, echoes the same destiny of Atlantis. Alexandria’s ancient history since its foundation is full of mystical revelations. The prophecy that the city will be repetitively destroyed and rebuilt again is taken from Alexander’s dreams and is accounted for in Plutarch’s Parallel Lives2 (46-120 AD) and Arrian’s (92-175 AD) narratives in his Anabasis of Alexander.3 Arab medieval historians and travelers such as Aboul Hassan Ali Al Masudi (895-956), described as the Herodotus of the Arabs, recounts in his encyclopedic century book Meadows of Gold and Mines of Gems that Alexander had prepared for setting the signal for the beginning of the works to lay the foundations of the city, through a system of strings and bells. During his sleep, a crow rested on the strings and rang the bells. This being an involuntary act disturbed Alexander himself, considering it to be a bad omen. The myth continues when during the night monsters repeatedly surged out of the deep seas every night, and successively destroyed what was being built during the day. A collection of drawings of those monsters with human bodies and animal heads was prepared and put on the surface of the stones, so that when the monsters surged again and saw their own faces on the blocks, they went back to the sea and never returned again. At a later date the Alexandrian myth is brought again in the inscribed Krystek, Lee. ‘The Lost Continent: Atlantis’. Series of Articles [1997-2006]. Plutarch. Parallel Lives. 1919. 3 Arrian, F. Anabasis of Alexander. Arrian’s History of the Expedition of Alexander the Great and Conquest of Persia. Translated by Mr. Rooke. London. 1813. 1 2
viii
figurations of zoomorphites and a favourable horoscope set on the foundations of the famous Cleopatra’s needles in front of the Caesarium on the shores of the eastern harbour, in an act to protect the city from the curse of the monstrous sea.4 The later Arab historian Al Makrizi5 (1375) in his famous Khitat mentions the city taken by the swollen sea, referring to the earthquake that hit the city in 1341, causing the collapse of the Pharos. But since the time of Plutarch, Arrian, Al Masudi and Al Makrizi, our knowledge of such natural phenomena, their causes and effects have been rationally explored and scientifically determined. However, their consequences still persist, threatening our safety and existence, which require a priority concern and a coordinated effort to deal with the complexity of its issues. This study is both chronological and synchronic in its approach. It deals with the aftermaths and the historical effects of natural phenomena, and their implications on the Alexandrian coastal shores. But it also involves a multidisciplinary team of research experts, contributors, and sponsors, and may be considered a step forward in the right direction to reveal the city’s past history, and, more importantly, to contribute to guarding and protecting its environment from future threats. Moreover, it has brought back to the city its renewed spirit of multiculturalism, symbolically demonstrated in the contribution and the cooperation of a Graeco-Egyptian symbiosis, and in the much valued attachment and affinity of its Egyptiotis6 to their second homeland and patritha. Mohamed Awad
4 5 6
Al Masudi. Meadows of Gold and Mines of Gems.Translated by P. Lunde, C. Stone, and A. Sprenger. UK 1989. Al Makrizi. Mawa’iz wa Itibar Al Khitat wal Athar. 2 vols. Bowlak. 1854. Referring to the Greeks of Egypt in Diaspora.
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1. Introduction The submergence of ancient coastal sites, such as harbours, has been mainly attributed to progressive sea level rise and/or land subsidence, or both (relative sea level rise). Studies have also highlighted the significant role of impulsive natural events, such as earthquakes (Clark 1995; Reinhardt and Raban 1999), tsunamis (Boyce et al. 2004) and river floods (Stanley et al. 2004a). Nevertheless, the anthropogenic stresses on coastal regions and harbours which resulted in their submergence are not fully understood. 1.1 Location and physical geography Alexandria is located on the Mediterranean coast of Egypt and is bordered by Egypt’s Western Desert and the Mareotis Lagoon, a large shallow wetland, to the south, and by the fertile Nile Delta to the east (Rowe 1954) (Figure 1a, b). The city of Alexandria was constructed on a long ENE/WSW-trending coast-parallel ridge of Pleistocene age that extends from southwestern Alexandria to Canopus, the modern town of Abou Kir east of Alexandria. This ridge, called Abu Sir, reaches a height of 35 m in its western part and 6 m in Abu Kir, and it was formed by poorly to moderately cemented sandy carbonate, known as kurkar formation (Butzer 1960; Stanley and Hamza 1992; Hassouba 1995). The sediment age ranges from 90,000 to 110,000 BP (Shukri et al. 1956; El-Asmar and Wood 2000). This ridge separates the shallow, brackish Mariotis lagoon, now called Maryut (Loizeau and Stanley 1994), to the south from the ports that lie to the north. The area of both ports (East and West Harbours) was formed between two carbonate sandstone kurkars. Seawater flooded the basin in between during the transgression, about 8000 years BP, and wind and wave driven currents deposited clastic sediments at an average rate of 1–3 mm/year. The Holocene sediments that were trapped in this significant harbour formed marine calcareous sand, muddy sand and mud. The association of distinct biological components, failed slump-like sediment strata and important hiatuses in the Holocene sediments have recorded the episodic influence of impulsive natural events, such as storm surges, seismic shocks and tsunamis (Stanley 1
Figure 1a: Site map of coastal Alexandria.
Geophysical Phenomena and the Alexandrian Littoral
2
1. Introduction
Figure 1b: Sites with valuable geomorphological and archaeological features in the Alexandrian coastal zone.
and Bernasconi 2006). Furthermore, high-relief carbonate features occur seawards and include Pharos Island to the NW, the harbour margin to the NE, as well as several small islets offshore (Butzer 1960; Jondet 1916; Stanley and Hamza 1992; Wali et al. 1994). Two large and submerged carbonates, reef-like features, have been mapped in the east-central sector of the East Harbour (Goddio et al. 1998). 3
Geophysical Phenomena and the Alexandrian Littoral
In Alexandria and its environs, total annual rainfall reaches an average of 200 mm. More specifically, the precipitation is concentrated from November to February, with almost no rainfall from May to early October. The mean annual air temperature is 20.4 °C, ranging from a monthly mean of 14 °C in January to 26 °C in August. Alexandria’s tidal regime is characterized as micro-tidal, with a range of up to about 30 cm, and, also, the sea-surface temperatures range from temperate to warm, i.e. between 16.7 °C and 26 °C. The salinity of the surface has an average rate of 38.8‰. Water masses are driven by coastal currents towards the east, having a mean velocity of 143 cm/s. In the coastal region of Alexandria, during summer, winds that derive from NW and W predominate and during winter they originate from SW. During winter, also, on the inner shelf of the wider coastal region of Alexandria, heights of waves north of the East and West Harbours reach 1.5 to 2 m; when entering the two ports the height decreases, reaching 0.5 to 1 m. This wave activity leads to abrasion of the sediments of the harbour floor, especially at shallow depths. The swell in the littoral is 40–75 cm according to Manohar (1981) and Naffa (1995). Analysis of hourly tide-gauge observations over ten years (1996–2005) in Alexandria showed that the short term variations in sea level is a combination of only ± 20 cm elevation due to astronomical tide, and up to 1 m elevation under the effect of meteorological factors, such as air temperature, wind regime, atmospheric pressure and steric effect (Eid 1990; Saad et al. 2011; El-Geziry and Radwan 2012; El-Geziry 2013). The mean sea level between the daily readings of high and low water level during the period 1898–1906 has been set as the mean sea level (m.s.l.) datum at Alexandria Harbour and this was found 33.8 cm above the zero of the installed tidal gauge (Dawod 2001). The m.s.l. for the period 1944–1989 was calculated at 40.0 cm (Frihy 1992), for the period 1956–1966 it was at 44.1 cm (Sharaf El-Din 1975), for the period 1974–2006 at 47.9 cm (Said et al. 2012), and for the period 1996-2005 at 50.67 cm, above the zero of the installed tide gauge (El-Geziry and Radwan 2012). Particularly over the last 100 years, climate change has contributed to the increase of the relative sea level. It is known that the average sea level worldwide is rising at a rate of about 1 mm/year, a rate that approximately applies to the Eastern Mediterranean (El-Sayed 1996; Serageldin 2014). Nevertheless, Evelpidou et al. (2018) in a recent study of the fish tanks in Alexandria concluded that the relative sea level has risen 70 cm since Greek-Roman times (see Chapter 10). The study of tide-gauge data over the last 60 years in Alexandria’s West Harbour reveals that the relative sea level in the area is rising. El Fishawi and Fanos (1989), Sharaf El Din et al. (1989) and Frihy (1992) have calculated that the rate of relative sea level change in the coastal zone of Alexandria ranges from +2–2.9 mm/year, while Frihy (2003) 4
1. Introduction
estimated that the relative sea level change in the port of Alexandria is +1.6 mm/year. On the other hand, Emery et al. (1988), based on short-term measurements, calculated that the rate of the relative sea level change is -0.7 mm/year (i.e. sea level falls due to tectonic movement of the land). East of Alexandria, from Abu Qir to Port Said, the rate of relative sea level change increases. El Fishawi and Fanos (1989) estimate a rise rate of 2.4 mm/year, Emery et al. (1988) a rate of +4.8 mm/year, and Frihy (2003) a rise ranging from +1.0 mm/year on Lake Burullus, and up to +2.3 mm/year in Port Said. The prevailing winds in Alexandria are of NW direction, as it was in ancient times (Stanley and Bernasconi 2006). The same authors mention that the mean wave height is about 2 m, while large waves reach 4 m. According to Chalari (2007), the maximum height during winter is 5.5 m, in spring 4 m, and 3.3 m in summer. Waves of 4 m height have a return period of 1 year, while 8 m waves have return periods of 100 years according to Aelbrecht et al. (2000). In contrast, storm waves of 7.6 m in height were calculated to occur with a return period of 50 years, while waves over 8 m occur with a returning period of 100 years (Iskander 2013); Shah-Hosseini et al. (2016) mention that storm waves higher than 9 m occur every 100 years. According to Frihy (1992), the subsidence rate in Alexandria during the last 60 years is 2 mm/year, while Frihy et al. (2010) consider Alexandria as relatively stable over the long term, providing subsidence rates of 0–0.5 mm/year. The rate of the relative longterm mean sea level rise for the period 1944–1999 has been estimated by Dawod (2001) to be 1.7 mm/year, while other researchers provide values in the range of 1.6–2.9 mm/ year for various periods of observation (Chalari et al. 2009). For the East Harbour, covering the 2300 years from the foundation of Alexandria, the rate of the long-term relative mean sea level rise is calculated from archaeological evidence at 2.9 mm/year (Stanley and Bernasconi 2006). Subsidence rates, based on core stratigraphy, range from 0.9–4.3 mm/year, varying irregularly from west to east along the northern Delta coast and averaging ~2.5 mm/year (Stanley and Toscano 2009). 1.2 Geological characteristics The study area is located on the relatively tectonically stable margin of northeast Africa. The recorded periodic instability that affects this region results from readjustment to down warping (sediment compaction faulting, isostatic lowering) of the thick underlying sedimentary sequence (locally exceeding 4000 m). The thin Holocene cover of unconsolidated deposits overlies Quaternary and Tertiary sequences of Nile Delta origin that, in turn, are superposed on Mesozoic sedimentary units (Said 1981; Schlumberger 1984). This sector, directly west of the Nile Delta, has been periodically affected by quite strong seismic tremors (Kebeasy 1990), growth faulting (Stanley 2005) and destructive tsunamis (Guidoboni et al. 1994). Generally, the low-lying region of the 5
Geophysical Phenomena and the Alexandrian Littoral
Nile Delta is subjected to significant differential subsidence (Figure 2). Τhe analysis of several core samples conducted in the East and West Harbours, as well as the description of surficial sediments from the coast and the shelf of Alexandria, have shown that Holocene deposits have accumulated directly upon the Pleistocene kurkar limestone. In addition, in the aforesaid area bioclastic and muddy carbonate sand strata can be found, interbedded with finer-grained sandy silt, silty mud and dark organic-rich layers (Jorstad and Stanley 2006; Stanley and Bernasconi 2006; Stanley and Landau 2010) and minor amounts of wind-blown quartz silt (Yaalon and Ganor 1979). The coastal zone is often affected by earthquakes of large magnitude, making Alexandria a hazardous place, even though it is characterized as an area of small to medium seismic activity. In general terms, these large earthquakes occur on tectonic plate margins such as the Hellenic Trench, Red Sea and Aqaba Bay (Maamoun et al. 1984; Kebeasy 1990; Ambraseys et al. 1994). These seismic zones lie at a distance of 300–600 km from Alexandria, thus their tectonic activity generates the fault zones, some of which bound the Nile Delta; therefore, the Delta shape is tectonically controlled (Zaghloul et al. 2001). These major fault zones are (Figure 3): a) the QattaraEratosthenes zone, forming the western limit of the Nile cone and trending NE–SW (Neev 1977; Frihy 2003); b) the Temsah fault zone (Abdel Aal et al. 1994), which is the eastern boundary of the cone and trending NW–SE; c) the Suez-Cairo-Alexandria zone (NW–SE), comprising the western limit of the Nile Delta (Ben-Avraham et al. 1987; Frihy 2003); and d) the Pelusium zone (NE–SW), comprising its eastern limit (Neev 1977). Additionally, Alexandria is also influenced by smaller faults, such as the Abu Qir and Rosetta faults, located some km east of Alexandria (Zaghloul et al. 2001). The city of Alexandria has suffered from 25 destructive earthquakes in the period between AD 320 and 2000, nine of which had their epicentres on its coastal zone (Maamoun et al. 1984; Ambraseys et al. 1994; El-Sayed et al. 2000). The other 14 tremors had their epicentres in the Eastern Mediterranean region (i.e. Hellenic Arc). The earthquakes in the marine area north of Alexandria are characterized by small to medium magnitudes (Ms = 6.7), while those produced in the East Mediterranean present relatively large magnitudes (Ms = 7.8) (El-Sayed et al. 2004). The former ones, despite their moderate magnitudes, were felt with intensities reaching IX on the Medvedev–Sponheuer-Karnik scale (MSK), which is a macroseismic intensity scale used to evaluate the severity of ground shaking on the basis of observed effects in the area of earthquake occurrence (Ambraseys et al. 1994). The 1955 event (MS = 6.7) was the latest locally damaging earthquake. During this earthquake a few people were injured and a considerable number of adobe houses were destroyed, as well as damage to a few concrete constructions (Maamoun et al. 1984; Ambraseys et al. 1994). Generally, the duration of shaking in the city of Alexandria from those earthquakes in its coastal zone did not exceed a couple of seconds (Ambraseys et al. 1994). The 6
1. Introduction
Figure 2: Long-term average Holocene rates of subsidence along the Nile Delta based on stratigraphic analyses of radiocarbon-dated core data (after Stanley and Warne 1998). Sites: A: East Harbour, B: East Canopus, C: Herakleion, D: NW Burullus lagoon, E: SE Burullus lagoon, F: Tell Tinis and G: Pelusium.
latter ones (MS = 7.8) were felt with intensities reaching MSK VI. These earthquakes, being more remote than the first ones, were generally felt in Alexandria for around 3 minutes or more, according to Ambraseys et al. (1994). The most severe damage in Alexandria was related to events located in the Eastern Mediterranean (Ambraseys et al. 1994; El-Sayed et al. 2004). Apart from these recorded earthquakes, modern and historical, there were clearly unrecorded events that caused disasters. For example, in Abou Kir, part of the city of Alexandria, the cities of East Canopos, Menouthis and Herakleion, positioned at the mouth of the Canopic branch of the Nile, were completely destroyed and submerged in the gulf of Abou Kir, under 6–8 m of water, and probably a destructive earthquake played a role in this. On the other hand, Stanley et al. (2001) concluded that the west branch of the Nile Delta, the so-called Canopic branch during ancient times, migrated almost 30 km east of Cape Abou Kir, developing finally the Rosetta Branch in the second millennium AD. The source and date of destruction of these cities are not exactly known and no details are available; however, the disasters (land subsidence or earthquakes) most likely took place during the 7th or 8th century, as indicated by the coins and jewelry excavated (Geotimes 2000; Stanford Report 2000; El-Sayed et al. 2004). Stanley et al. (2001) attribute the Canopic river bank sediment failure triggered by exceptional flooding of the Nile to the end of the first millennium AD. 7
Geophysical Phenomena and the Alexandrian Littoral
Figure 3: The major fault zones of the wider Alexandria area (Zaghloul et al. 2001).
The coastal zone of Alexandria is also vulnerable to tsunamis. Although tsunamis are rather rare in the Eastern Mediterranean, highly destructive ones were recorded at several locations in the Mediterranean, but only few events are known to have affected Alexandria on the north coast of Egypt (Eckert et al. 2012). One of the largest tsunamis resulted from the earthquake of 8 August, AD 1303, which struck many localities in the Mediterranean basin and reached the Egyptian coast (Maamoun et al. 1984; Kebeasy 1990; Ambraseys et al. 1994; Goiran et al. 2005; Zerefos et al. 2008). In Alexandria, preceded by heavy thunder and lightning, the stability of the whole region was threatened. Soyuti (after Ambraseys 1961) states that the advance of the sea caused by that earthquake submerged half of the town of Alexandria and overwhelmed and killed many thousands of people. The rapid whirlpools created by the retreating waters destroyed many ships, leaving them wrecked, while others were hurled by the waves onto roof tops; some were 8
1. Introduction
even washed up several miles from the shore (Papazachos 1990; Ambraseys et al. 1994; Riad et al. 2003; Hamouda 2006). This tsunami also damaged the great lighthouse, and much of the city wall was destroyed (El-Sayed et al. 2000; Papadopoulos et al. 2010; 2014; Shah-Hosseini et al. 2016). Historic records indicate that, in Alexandria, more than 5000 people lost their lives and more than 50,000 homes were destroyed after the earthquake of AD 365 that destroyed much of Crete and caused a tsunami that struck Alexandria (Ambraseys et al. 1994). According to radiocarbon dating, as well as land observations, this was the only earthquake of large magnitude in this area over the last 1650 years (Shaw et al. 2008). The tidal wave of AD 365 reached the coast of Alexandria from a SW direction and therefore the Island of Pharos could provide no protection for the city, and consequently the Heptastadion flooded (Chalari 2007; Shaw et al. 2008). In addition, this tsunami destroyed coastal regions as far as western Egypt and eastern Sicily. Nowadays, evidence of impacts from tsunamis has been traced in sediment core records (Goiran et al. 2000). Goiran et al. (2000) analyzed sediment cores near the East Harbour and identified a layer, dated around the 6th–7th c. AD (Late Roman period), which may correspond to one or more tsunamis and/or high energy storms. Apart from earthquakes and tsunamis, Alexandria has also been affected since ancient times by sedimentation, which constitutes an important and dominant geological process in this area. The function in the past of many small channels that diverged from the Rosetta Nile branch resulted in Alexandria’s sedimentation. The provoked mass loading, isostatic depression, tectonic readjustment by fault, the slumping and compaction of the unconsolidated sediments, as well as debris accumulation by the various natural catastrophes and by anthropogenic activity over the last 2500 years, has resulted in the 5–7 m higher relief, compared to ground level in antiquity, according to archaeological excavations. Finally, there is another phenomenon that affects Alexandria and magnifies the submersion of the northern coast of the Nile Delta, and more specifically the east coast of Alexandria: the relative sea level rise. Sea level variations around Alexandria have been the focus of many researches (e.g. Eid 1990; Mosetti and Purga 1990; Jorda et al. 2012; El-Geziry 2013). To this effect, according to long-term observations (over the past 2300 years), the relative sea level change in the Nile Delta is upward. This ascertainment results from the presence of submerged port facilities of ancient cities in the coastal zone of the Delta. More specifically, in Alexandria’s West Harbour ancient breakwaters were found, whose construction age has not been completely verified, at depths of 5 m and 8 m below sea level (Jondet 1916). In the East Harbour, ancient moles of the Hellenistic period were found to a depth of 5.5–6.5 m (Goddio 1998; Stanley and Bernasconi 2006). The fact that the antiquities in the East Harbour were at least 1 m above sea level at 9
Geophysical Phenomena and the Alexandrian Littoral
the time of their construction leads to the conclusion that the total relative sea level change ranges approximately between 6.5 m and 7.5 m. Therefore, the average rate of relative sea level rise over the last 2300 years in the coastal zone of Alexandria ranges from about +2.8 to +3.4 mm/year. The same upward trend in sea level is also observed during Holocene (8000–6500 BP). Stanley (1988; 1990), Stanley and Warne (1993), and Warne and Stanley (1993) calculated that the rate of the relative sea level change is 3mm/year in the region of Alexandria (Chalari 2007). 1.3 Geomorphology According to the geomorphological setting, the Egyptian margin, west of the Nile Delta, is defined by a straight SW–NE coastline that presents a length of more than 100 km. In this area, and particularly between the Arabian Gulf to the west and the Nile Delta east of Alexandria, the only suitable sites for the construction of protected ports were the two bay-like re-entries adjacent to Pharos Island. The West Harbour has a rectangular shape with an area of about 26 km2 and a length of nearly 10.7 km, between the SW margin (El Agami) and the Heptastadion coast to the east. The West Harbour has mostly depths exceeding 10 m. Its floor is asymmetric, deepening gently from the outer kurkar islet margin towards the SE, while towards Alexandria’s shoreline it becomes rapidly shallower, from 20 to 15 m. The port can be subdivided into three coast-parallel bands according to the depth (NIMA 1999). More specifically, it can be subdivided into a wide northern (seaward) one, with shallow to intermediate depths from 1 to 10 m, a deep middle sector with depths ranging from 10 to >20 m, and a very narrow, steeply-inclined southern band along the coast with intermediate depths, generally 500 m wide) submerged kurkar highs are distributed in the east-central sector of the port (Goddio et al. 1998), probably submerged parts of the kurkar ridge I. The harbour is now almost completely enclosed artificially by protection structures, which are emplaced along its northern margin. During the early Hellenistic period, under Greek rule, several important port facilities were constructed in the eastern and western sectors of the East Harbour (Goddio et al. 1998; Bernard and Goddio 2002). By Roman times, the coastline bordering the East Harbour had been moderately reshaped by large warehouse and dock structures, built in order to absorb trade that had been previously directed to Athens and other Eastern Mediterranean cities. The area of the East Harbour was once a sub-aerially exposed topographic depression that was formed between a series of carbonate kurkar high-relief features. During the early Holocene, land subsidence, sea level rise, and consequent landward coastal retreat, resulted in flooding by marine water and thus the East Harbour was formed. There are several sediment sources to the harbour. At first, substantial soil runoff, as well as sediment, much of it carbonate, eroded from the bordering emergent land and the areas is defined by the accumulation of considerable terrigenous sediment on the basin floor. Clay sediment was also transported landwards in the harbour through coastal erosion, storm surges and bottom currents. Organic and detrital material was deposited into the harbour, because of transport on the seabed and suspension in the water column (Stanley and Bernasconi 2006). Significant amounts of carbonate particles, including shell fragments, accumulated in the harbour from coastal areas west of Alexandria and the Nile shelf offshore. Meanwhile, quartz was largely transported from the mouths of Nile branches, delta margins and the Nile shelf to the ENE (El-Wakeel and El-Sayed 1978; Hassouba 1995; Shukri et al. 1956; Summerhayes et al. 1978; Warne and Stanley 1993). In addition, wind transport was a significant sediment source for the harbour. The wind-released material includes coarse sands originated from contiguous desert sectors (Stanley and Bernasconi 2006), as well as silt and dust from more distal desert terrains in Egypt, Libya, Sudan, and Chad to the S and W (El-asmar 2000; Guerzoni and Chester 1996; Yaalon and Ganor 1979). Generally, the outer northern margins of both harbours are formed by linear, discontinuous series of emergent to shallow submerged islets and ridges formed of kurkar. The Maryût Lagoon is located on the western margin of the Nile Delta. It is a vast coastal plain, located beneath the Delta (Hume and Hughes 1921; Warne and Stanley 1993; Goodfriend and Stanley 1996; Flaux et al. 2011). It is located below sea level and is separated from it via a coast, which contains Pleistocene sediments (El-asmar and Wood 2000). Since antiquity, the Maryût Lagoon was a basin containing slightly brackish water in communication with the Nile, through several canals, and with the 11
Geophysical Phenomena and the Alexandrian Littoral
sea as well, with secondary channels, as described by Strabo: ‘[Alexandria] is bathed by two seas, to the north by the Egyptian sea, as it is called, and to the south by the lake of Mareia, also called Maréôtis’ (Strabo XVII, 7, in Yoyotte et al. 1997). This is how the Canopic branch works, which serves the entire system of the Mareotis Lake (Toussoun 1922), and was also the main source of natural fresh water for both Alexandria and the Maryût Basin. The decline in water flow, in this branch, began in the Roman period, while there was a gradual increase to the east, and more specifically to the Rosetta branch (Guest 1912; Toussoun 1922; 1926; Chen et al. 1992; Stanley et al. 2004a; Ducène 2004; Stanley and Jorstad 2006). It is therefore probable that the drying of the Canopic branch may be the result of the diversion of its increasing flow into the irrigation system of the Delta’s western margin, which has contributed significantly to the development of Alexandria (Bernard 1970). The decrease of water flow is caused by two main factors – the deposition of sediment load and the decrease of the slope. The two phases of the Maryût Basin show a slow desiccation process of the Nile’s western boundaries, most likely with a subsequent reduction in the Canopic branch, 2000 years ago. The progressive blockade of the Canopic branch is placed between the 10th and 14th centuries AD, and is a process that took place gradually (Hairy and Sennoune 2006). The expansion of the Maryût Basin appears to have fluctuated some 2000 years ago. The city of Alexandria experienced major political changes from the 7th century AD. At the beginning of this century an armed conflict between the Byzantine emperors Phokas and Heraklion took place in Maryût (Rodziewicz, 1998). One of the generals was ordered to fill the basin supply channels to reduce the water level. This rapid reaction, if any, shows the dependence and viability of the lagoon by preserving the channels connecting the Nile. All areas associated both with economy and exports were quickly abandoned. At the same time, the construction in Alexandria of the newly fortified city completely dissociates the city from the lagoon (Haas 2001). Between 930 and 1070, the Roda Nilometer in Cairo records successive phases of Nile levels, including floods and water shortages. This last phase may have favoured the creation of a deficit in the Maryût Basin, which was less likely to communicate with the Nile. At the end of the 12th century AD, the commentator Ambul Hassan al-Makhzoumi describes the irrigation process during the Nile overflow in the Behera area (Toussoun 1926), the western Rosetta branch. Toussoun (1926) also mentions the reconstruction of an important Behera channel between 1263 and 1265 AD, during the reign of Mamluk Sultan al-Zaire Baybars. These testimonies reflect the resumption of agricultural activities in the Behera area, and this could be interpreted as stopping the operation of the Maryût evaporites Basin, through irrigation in the area. The region is affected by a major demographic crisis due to the plague, which also occurs in Europe during the same period. The second drainage of Maryût, from the 12th century AD, affecting 12
1. Introduction
all irrigation channels, resulted in the general decline of Behera. The northwestern Delta was then linked to the Nile again by large-scale irrigation projects that began at the same time as the economic development of Alexandria, during the reign of Méhémet Ali, in the early 19th century.
13
2. Subsidence regime Taking into consideration all the historical records regarding the city of Alexandria, many researchers from all over the world were attracted by the grandeur of this city and the unanswered queries about what provoked the submergence of ancient littoral Alexandria. 2.1 Bathymetry A preliminary study of the East Harbour of Alexandria bathymetry was conducted by Professor E. Livieratos of the Aristotle University of Thessaloniki (personal communication), based on maps from the end of the 18th century until the beginning of the 20th century, in an attempt to trace and understand the subsidence regime of the area (Figure 4). In particular, the following maps were used: the French map of ‘Guillaume d’Anville’, dated around 1750– 1799; the ‘Dépôt de la Marine’ (1867); and British Admiralty maps 1833, 1857 and 1920. The maps were available in different scales and projecting systems. The following methodology for cartographic analysis was adopted, with the analysis applied to the inside sector of the East Harbour extending almost 1000 m seaward from the entrance of the port. As a general reference the British Admiralty map of 1920 was used. The analysis was made by developing the bathymetric relief of the new harbour of Alexandria at different time periods between 1750 and 1920. On the reference map of 1920, the other four maps (by suitable best-fitting transformations) were superimposed for comparison. For the best-fitting transformation some characteristic reference points were used, such as the reefs-shoals of Le Diamant, El Nassar, El Hassan, Ganem, El Fullfill and El Jemel, as they are noted on the map ‘Depot de la Marine’. Afterwards, for each map, files of the respective bathymetric values, reduced in metres, and coordinations were created. From the files of coordination-depths, isodepth lines were drawn (1 m depth apart) and the isospace zones of the bottom. The results are shown in Figure 4.
14
2. Subsidence regime
Figure 4: Bathymetric maps of the East Harbour of Alexandria, based on historical maps dating from the end of the 18th to the beginning of the 20th century AD.
15
Geophysical Phenomena and the Alexandrian Littoral
Figure 5: Comparison of bathymetric profiles between Le Diamant–El Hassan, in 1833 and 1920, lead to the suggestion of subsidence in the sea floor of >1.5 m.
The bathymetric profile of the axis Le Diamant–El Hassan, based on the maps of 1920 and 1833, is shown in Figure 5. A subsidence of >1.5 m between the reefs of Le Diamant and El Hassan over a period of one century has been concluded (Figure 5). 2.2 Submerged ancient structures In the coastal zone of Alexandria there are two opposing categories of submerged ancient structures, related to the degree of their destruction. In the first category, there are submerged structures showing relatively small damage. Representative examples in the East Harbour include nearly intact paved walkways, large mortar blocks with wooden frames, and some rock wall and pier segments. Also, the NW trending pier (about 160 m long) near the Poseidium presents small offset and damage. The second category is represented by ancient submerged structures that display obvious effects 16
2. Subsidence regime
of damage. These include broken and offset paved walkways, rubble layers of displaced construction debris, and broken and irregularly distributed large columns. Among other deformed and displaced structures in the East Harbour, there are tilted framed mortar blocks, collapsed masonry, and offset foundation bases that incorporate a mix of the once underlying rock fill and substrate sediment (Bernard and Goddio 2002). Historical records indicate that the structures in and around the area of the two harbours of Alexandria were periodically damaged by abrupt and severe natural events, such as earthquakes, storm waves and tsunamis. In their geoarchaeological study, Stanley et al. (2006) revealed that human activities in nearshore and port settings also triggered sediment deformation and construction failure. According to their study, analysis of radiocarbon-dated Holocene cores and submerged archaeological excavations record a significant incidence of sediment destabilization and mass movement in the ports since human occupation in the 1st millennium BC. Geological analysis indicates that most features built in the East Harbour were subsequently submerged, largely as a result of sediment substrate destabilization and mass failure. Subsidence was triggered by natural events such as earthquakes and tsunamis (Kebeasy 1990; Guidoboni et al. 1994; Pirazzoli et al. 1996). Submergence also resulted from inadequate construction of pilings and insufficient compaction of underlying water-saturated sediment for structural support, the latter inevitably leading to overloading and substrate failure (Malaval and Jondet 1912; Stanley et al. 2006). The European Institute for Underwater Archaeology (IEASM) and the French mission of the Centre for Alexandrian Studies (CEALex) have carried out systematic marine archaeological excavations in the East Harbour. Numerous artifacts have come to light, and large Greek, Roman and Byzantine structures have been exposed (Goddio et al. 1998; Bernard and Goddio, 2002). Excavations have revealed remnants of extensive submerged structures, such as paved walkways, walls and docks, along with statues, ceramics and jewelry. These findings are located at depths reaching about 7 m, and many are found partially buried by sediments. The most important structures in Alexandria’s early history are three port facilities constructed in the E and SE parts of the East Harbour, related to the navigation, trade and the centre of municipal activity, where the Timonium, a palatial summer house built by Marc Antony, and the Poseidium, a temple of Poseidon situated close to the East Harbour, were constructed (Goddio et al. 1998). In addition, there are the Navalia port structures, located in the west of the East Harbour, adjacent to the Heptastadion (Figure 1a), as well as large remnants of the famous Lighthouse that were detected underwater in the area off the eastern Pharos Island (Empereur 1998). The Lighthouse was destroyed almost entirely in the 14th century AD by earthquakes, and probably by tsunamis, as will be discussed in the next chapter. HIAMAS carried out marine excavation missions beyond the Silsilah promontory (ancient Akra Lochias), which is largely submerged. 17
Geophysical Phenomena and the Alexandrian Littoral
On the other hand, observations in the West Harbour, carried out by the port engineers, have shed light on the association between failed constructions, mass flows and subsidence (Malaval and Jondet 1912; Jondet 1916). During expansion of Alexandria’s port, engineers witnessed that structures emplaced upon the kurkar cemented limestone usually remained stable, whereas structures built on unconsolidated sediments often presented damage and subsidence. Additionally, port engineering reports (Malaval and Jondet 1912) and mapping by divers (Goddio et al. 1998) indicate sediment failures and lateral material flows, in some cases for tens of metres or more, at the sites where heavy structures were placed on weak, more saturated silt and clay sediments. The notable phenomenon is that subsidence and sediment displacement occurred three or four times successively at the same site, usually without warning. The subsidence regime in the coastal zone of Alexandria is greater inside the East Harbour, as confirmed by the 2–10 m submergence of the ancient sites of Timonion, Antirodos, the Royal Port installations on the western side of the Akra Lochias promontory (inside the Port), the remains of the ‘Royal Quarters’, the Diabathra, and the Temple of Isis Lochias on top of the promontory’s eastern side. In summary, historical sources indicate that at least two natural events in the 3rd and 12th centuries AD were the cause of the speeding up of the submersion of the ground in many areas of ancient Alexandria. Historic documentation points out those structures, both in Alexandria and its harbours, periodically experienced effects of forcible natural events (Guidoboni et al. 1994). Notable examples are the several earthquake tremors during Byzantine time (Pirazzoli et al. 1996) and a few tsunami wave surges during the 1st millennium AD (Figure 6). As a result, the coastal area of Alexandria, as well as the city itself, suffered major destruction, probably partially due to liquefaction and soft sediment failure. A substantial submergence happened in the Abou Kir Gulf, east of the Abou Kir promontory, which is attributed to earthquakes and Nile floods discussed in the following paragraphs. All the aforesaid suggests that the coastal morphology of Alexandria is now markedly different from how it was in 2300 BP.
18
2. Subsidence regime
Figure 6: Cumulative diagram of earthquakes and tsunamis occurring in Alexandria over the past 2000 years (Goiran 2001; Chalari 2007).
19
3. Evidence of offshore subsidence in Alexandria What is now referred to as the ancient port of Alexandria is divided into an eastern and western basin, both facing north; they are bounded to the north by an almost linear, discontinuous series of emergent to slightly submerged islets and ridges. In particular, the reefs of El Hassan (31013' N, 290 54' E) and El Nassar (31012.51' N, 290 54.27' E) are located in the northeast sector of the East Harbour, and the Le Diamant reef (31ο 12'55’ Ν, 29ο 53' 12" Ε) northeast of the Quaid Bay fortress. On the map of the Codex Urbinate 277 (1472), now kept in Biblioteca Apostolica Vaticana, these reefs are depicted as large rocks protruding above mean sea level (Figure 7), but are now submerged deeper than 7–8 m. El Hassan and El Nassar reefs are marked on all modern charts (Vauhello 1839; Mansell 1869; British Admiralty 1935–1936). The Le Diamant shoal, now about 1.5–2 m below sea level, is depicted in Bonaparte’s ‘Description de l’Egypte’ (Denon 1809), in a drawing made in 1798, as a large rock on top of the reef, well above mean sea level (Figure 8). During bombardment in the 1880s by the British, Le Diamant was leveled but was still visible. The time elapsed since the Bonaparte record is 210 years, and the British bombardment was 130 years ago. Alexandria has been repeatedly struck by natural disasters in its ~2400-year history. The city has been destroyed at least twice, then largely disappearing from, or ignored by, historical chronicles, then recovered, described, only to disappear from chronicles again. The seismotectonics, earthquake and tsunami hazards affecting Alexandria are described by several researchers (Shaw et al. 2008; Valle et al. 2014; England et al. 2015). Zerefos et al. (2015) described environmental disasters based on the texts of Arab historians and travelers from the 8th to the 15th centuries AD. Al-Makrizi (1227) noted the intrusion of Mediterranean seawater in Alexandria and speculated that it occurred even before the Arab conquest. In his Al-Khitat (‘The Plans of the Cities’), he wrote that during a large earthquake at the time of the Roman 20
3. Evidence of offshore subsidence in Alexandria
Figure 7: The map of the Codex Urbinate 277 (1472), depicting the present 12 reefs as protruding features.
21
Geophysical Phenomena and the Alexandrian Littoral
Figure 8: Le Diamant, depicted above sea level (Panchoucke 1821-9).
Emperor Constantine, the sea rose and struck several locations and many churches, and 17 towers of the wall of Alexandria collapsed. Then, that ‘the sea has since continued ceaselessly swallowing little by little whole sections of the city’. Al Makrizi also referred to the description of an earlier visitor to Egypt quoting him as writing ‘the sea beat the city, which ended up in the sea ... Can you not see the buildings and their foundations submerged in the sea today with your own eyes!’ Al-Asyuti, or Djalal el Din (1998), noted, referring to an event in 1303, that ‘the sea rose up, reaching the middle of the town; it drowned livestock and people, while ships were carried inland and countless houses, countless people, disappeared beneath the ruins’. While there is little doubt there was a large earthquake in 1303, its epicentral location remains a source of speculation (England et al. 2015). The emergent/slightly submerged islets and ridges are formed by kurkar carbonates. Submerged kurkar highs are also distributed in the east-central sector of the East Harbour (Goddio et al. 1998), while others form submarine reefs, seawards from the harbour entrance. The largest of them include El Hassan, El Nassar and Le Diamant: these reefs present the same lithology as the neighbouring kurkar outcrops (Stanley and Bernasconi 2006). The data of this study was derived from both archival map resources and previous and recent fieldwork. The area was systematically surveyed, and the submarine part studied by scuba diving. During fieldwork, the most important geomorphological characteristics were mapped. Geographic locations of measurements are reported as Long/Lat coordinates, with an average accuracy of ±5 cm using GPS. The observed features were photographed and measured in relation to sea level at the time of 22
3. Evidence of offshore subsidence in Alexandria
observation. Precise depth measurements were obtained using a hand-held sonar. Multiple measurements were performed and the average is provided as the depth value. Historic maps and written records were reviewed to determine whether the reefs were represented as protruding above the waterline or shallower in the past, and might be compared to today’s positioning of the reefs. AMS radiocarbon was used for the dating of ship finds, utilizing Klaus-TschiraLabor für Physikalische Altersbestimmung, Curt-Engelhorn-Zentrum Archaeometrie gGmbH, Mannheim, Germany, in cooperation with the Dimokritos Research Centre, Athens, and the results were cross-checked at the Oxford Radiocarbon Accelerator Unit. For age calibration, OxCal v.4.2.3 (Bronk Ramsey et al. 2013) was used, with the most recent dataset from 2013. The following radiocarbon measurements were made as presented. Isotopic fractionation has been corrected for using the measured 13C values measured on the AMS. The quoted 13C values are measured independently on a stable isotope mass spectrometer (to 0:3 per mil relative to VPDB). The dates are uncalibrated in radiocarbon years BP (Before Present – AD 1950), using a half-life of 5568 years (Figures 9, 10). The remains of several ship wrecks have been noted during HIAMAS (Hellenic Institute of Ancient and Mediaeval Alexandrian Studies) surveys, on the seafloor and the contours of the El Hassan. Of interest are the remains of two wrecks, as they bear witness to the submergence of the reef. The number of broken amphorae, pottery sherds, ballast made of pebbles, as well as an iron anchor, suggests a Late Roman/Early Byzantine wreck. No timber or other datable material from this wreck has yet been found. Based on the remains of its cargo and shape of its anchor, we can infer that it dates sometime from the 5th to 7th centuries AD. The second wreck is more modern, as attested by structural timber wedged in the bed rock of the El Hassan (Figure 11). The sinking of this Late Roman/Early Byzantine ship was probably due to the ship’s keel striking the El Hassan reef, as evidenced by the scattered cargo. The second wreck is evidenced from a 1.35 m long, 0.16m high and 0.10 m wide piece of timber found wedged in rock cavity, firmly stuck at 290 54.285' E and 310 13.225' N, at a depth of about 10 m (Figure 11). This structural piece was likely a floor rider, or a floor frame positioned between the keelson and the keel of the ship. This timber collected from the second ship wreck was dated with 14C AMS at two laboratories. The ages obtained were between 143 ± 20 years BP (cal AD 1719-1780) and 197 ± 23 years BP (cal AD 1735-1806), with a probability of 95.4% (Figures 9, 10). Had the ship sunk without colliding, the keel would have disintegrated slowly, and its pieces might then have been slowly transported to shallower waters, so it is rather unlikely that the timber would have been wedged as it did. Similarly, if the ship had 23
Geophysical Phenomena and the Alexandrian Littoral
Figure 9: Age calibration provided an age of 1735–1806 AD (95.4% probability) for the timber sample dated by the Oxford Radiocarbon Accelerator Unit.
Figure 10: Age calibration provided an age of 1719–1780 AD (95.4% probability) for the same sample dated using the Klaus-Tschira-Labor für Physikalische Altersbestimmung, Curt-Engelhorn-Zentrum Archaeometrie gGmbH, Mannheim, Germany, in cooperation with the Dimokritos Research Centre, Athens.
24
3. Evidence of offshore subsidence in Alexandria
Figure 11: A piece of timber from a wrecked ship found at El Hassan reef at a depth of 10 m.
sunk in the vicinity of the reef, it is fairly unlikely that wave activity on the seafloor would have been capable of uplifting and wedging the piece as discovered at about 10 m depth. Assuming that the wave climate has remained the same over the past three centuries, one can use modern day estimates of offshore wave conditions. According to Galanis et al. (2012), the maximum significant wave heights in the Eastern Mediterranean do not exceed 5.4 m, based on simulations using the code WAM at a fairly coarse grid. Frihy et al. (2010) also report measurements of 5.4 m significant nearshore wave heights near Dabba, west of Alexandria. De Graauw (2017) considers that nearshore wave heights range from 1–4 m along the North African coast. Waves with 5.4 m significant wave height at 13 m depth are extreme by Mediterranean standards. They would have had a devastating impact along the Alexandria seashore, and, indeed, excessive flooding has been reported as increasing in the past decades, although quantification is missing. Even so, if one assumes a 5.4 m wave at 13 m depth with an 8-sec period, as has also been recorded in nearshore swell waves in other Mediterranean regions with similar fetch and trade winds (Maravelakis et al. 2014), then the resulting orbital velocities at the seafloor are too small to transport and wedge a piece of timber, as found. For these 25
Geophysical Phenomena and the Alexandrian Littoral
values, one estimated boundary layer thickness on a flat bottom is about 15 cm, so any timber on the seafloor would have hardly noticed the waves. On the other hand, if the waves were larger, they would likely be breaking at the reef, and the piece of timber would have been repeatedly moved, and would have likely broken into pieces. No such breaking is reportedly observed on the reef during storms. One would require a tsunami of 1 m height at 13 m, with a period of the order of tens of minutes, to convincingly exert forces capable of moving the timber, but then such a wave would have carried the debris field closer to shore. In the absence of reported tsunamis of such heights hitting Alexandria in the past 300 years, and the difficulty of arguing that currents from orbital motions from swell wave moved the timber, we are led to the conclusion that the piece of timber was likely wedged from a forced impact on the reef and stayed in situ since then. We are thus left with the possibility that, in the late 18th century AD, the tip of El Hassan was at a depth not exceeding 2–3 m (Figure 12). If correct, our analysis suggests a subsidence of the order of 6 m in about 200–250 years, or about 2.5–3 cm/year. This observation is consistent with the earlier map showing the three reefs as shoals or above sea level. Again, if El Hassan or El Nassar were historically more than 5 m below mean sea level, they would not have warranted their inclusion in early navigational charts, not to mention their being identified with special names. That piece of timber is not the result of a floating object, taken adrift, that ended being trapped at a depth of some 10 m. A floating piece of timber cannot be found at such a depth and it is proposed that it is due to the collision of the fore part of the underbody of a sea craft with an obstacle, i.e. a reef, which at the time of that incident was slightly under its floating line. The ancient remains scattered at the top and on the surface of the reef are mainly pottery sherds, some complete or broken amphorae, ship ballast composed of large pebbles, parts of the cargo of various commercial shipwrecks datable to Late Roman times, c. the 4th century AD; a nearly complete iron anchor may be dated 4th to 7th centuries AD. What actually happened to the small craft that collided on the reef, and left a small structural part, is conjectural. Notwithstanding the serious damage sustained, the boat could have safely made it to the nearby port. Another possibility is that the wreck remained entangled in the shallows of that reef and was promptly discarded by the action of the waves and swell, while its parts floated and washed up on the nearby shore. Although this structural piece of wood is the only remaining part of the more modern wreckage (no other evidence was found on the sea floor), it is most probable that 26
3. Evidence of offshore subsidence in Alexandria
Figure 12: Sketch of the ship, impact location, and a detailed design of the ship’s bottom.
the vessel was solely powered by sails. Considering a rough sea, with high waves, at a distance of some 600 m from the Pharillion, the captain made a left turn to enter the port. Unaware of the presence of two reefs (the El Hassan, but also the El Nassar), or miscalculating his course because of adverse weather conditions, the underwater part of the bow hit the reef. The draft was probably no more than 1.50 m, but because the vessel might have been in a trough, it could well have hit an obstacle located at up to 2–3 m below the surface of the sea. The collision was likely not frontal, but sideways, and because of its intensity the side planking of the bow under the waterline disintegrated, and a timber floor beam struck the rock and was wedged in it, as was discovered. The remains of the wooden vessel probably did not sink at once and were transported to another reef or shattered due to wave action on the coast. The question arises whether there are other geological triggers for such subsidence? The recorded periodic instability that affects this region results from readjustment to down warping (sediment compaction faulting, isostatic lowering) of the thick underlying sedimentary sequence (locally exceeding 4 km). The thin Holocene cover of unconsolidated deposits overlies Quaternary and Tertiary sequences of Nile Delta 27
Geophysical Phenomena and the Alexandrian Littoral
origin, which, in turn, are superimposed on Mesozoic sedimentary units (Said 1981; Schlumberger 1984). This sector is periodically affected by earthquake tremors (Kebeasy 1990; England et al. 2015), growth faulting (Stanley 2005) and tsunamis (Guidoboni et al. 1994; Shaw et al. 2008; Vale et al. 2014; England et al. 2015). Generally, the low-lying region of the Nile Delta is subjected to significant differential subsidence, but to date none of such size has been reported. According to the comprehensive catalogue by Ambraseys (2008) and the corrections to other derivative catalogues by Ambraseys and Synolakis (2010), there are no significant local earthquakes shown in the past 250 years. No similar changes have been reported in the neighbouring coastal zone. Stanley and Toscano’s (2009) measurements of land subsidence at seven archaeological sites on the Nile Delta margin do not exceed 4.3 mm/yr on average, for the last four millennia. Recent interferometric synthetic aperture radar (inSAR) measurements (Bouali 2013) suggest rates of up to 12 mm/yr in Mansoura and 10 mm/ yr in Ras El Bar, but show Alexandria to be relatively stable. Our measurement is much higher than inferred from onshore measurements. However, we note that subsidence rates as high as 6 cm/year have been reported for Tokyo for the period 1900–1975, but the current subsidence rates are around zero (Kaneko and Toyota 2011). 11 cm/year subsidence rates along the shores of Jakarta have been reported in the period 1974–2010 (JCDS 2011). Morton et al. (2013) have reported historical subsidence rates as high as 23 mm/yr in south-central Louisiana. We note that all these estimates are for overland subsidence and not for submarine sediments. Our estimate does not include the effect of relative sea level rise. Based on tide gauge data from the Mediterranean for the last 130 years, a continuous average sea level rise (SLR) at a rate of 1.79+0.47 mm/year has been estimated (Anzidei et al. 2014). Even if locally it averages up tο 1 cm/year, in the past two hundred years, SLR cannot explain differences with inland subsidence estimates. While our measurement is provocative, we are led to the conclusion that this subsidence, less than 1 km seaward from the mouth of the harbour, must be due to submarine sediment compaction. If our analysis is qualitatively correct, and similar rates of subsidence have been ongoing for the last millennium, a part of ancient Alexandria may lie buried in coastal sediments.
28
4. Palaeogeography According to historical records, the structures in and around the area of the two harbours of Alexandria were periodically damaged by abrupt and severe natural events, such as earthquakes, storm waves and tsunamis. Stanley et al. (2006), based on a geoarchaeological approach, revealed that human activity, since the 1st millennium B.C., had posed stress upon the aforesaid area, which triggered deformation and construction failure. For this approach (Stanley et al. 2006), core sections were recovered from the two harbours in order to study in detail the stratigraphy of the Holocene deposits that accumulated directly upon the Pleistocene kurkar limestone. In the West harbour, one important set included 65 closely spaced drill cores, located in the eastern part of the port. They were conducted for civil engineering purposes, primarily for the construction of marine lift and dry-dock facilities west of Pharos Island and they are presented in detail, in an anonymous report (1987). Other drillings in this port have also been described by Jondet (1916) and Attia (1954). In the East Harbour, eight vibracores were collected in May 2001 by Stanley and Bernasconi (2006). The analysis of the radiocarbon-dated Holocene cores, in combination with archaeological excavations, revealed an important historic coincidence. The sediment destabilization and mass movement in the ports date back to the human occupation of the area in the 1st millennium BC. Moreover, anthropogenic substrate failure is documented from the time of the city’s foundation by the Greeks, in the 4th century, up to the present. These failures were the results of construction on unconsolidated sediment substrates in conjunction with earthquakes, storm waves and tsunamis; however, engineering reports on port construction show that construction substrate failures occur, independently of episodic natural events (Malaval and Jondet 1912). Stanley et al. (2006) tried to ascertain that sediment destabilization was provoked by human activity, based on two types of data. The first was evidence of deformed sediments 29
Geophysical Phenomena and the Alexandrian Littoral
in the upper dated stratigraphic sections and the second was the confirmation that substrate failure took place during the period of human activity in and around the ports. The combination of the aforesaid data should demonstrate whether the failure occurred in regular or irregular intervals during the late Holocene (8000 years ago) and should also reveal the relative frequency of post depositional failure before and after Alexandria’s occupation. Stanley et al. (2006) determined the date of 332 BC as the chronological reference level, because it specified the chronological beginning of Alexandria’s rapid development. Another approach was made by Bernasconi et al. (2006), which included the recording of changes in lithofacies and assemblages of mollusks and foraminifera since the early Holocene in the East Harbour. The clear change in biofacies during the Greek to Roman periods is noteworthy (about 2100 to 1800 years ago), and it is attributed to the induced effects by human activity in the area, most likely resulting from the construction of the Heptastadion (Bernasconi et al. 2006). This conclusion is in agreement with other aforesaid studies and reflects the combined effect of human activity in the biostratigraphical environment. Finally, the stratigraphical analysis by Bernasconi et al. (2006) revealed that human activity in the area began at least 3000 years ago. Finally, nine failed sediment layers were detected in seven of the aforesaid eight East Harbour cores. Their lithological structures and radiocarbon dates are presented in detail in Jorstad and Stanley (2006) and Stanley and Bernasconi (2006). The two youngest deformed layers were dated at about 350 to 500 years BP, four layers at about 900 to 2100 years BP, and the oldest deformed layers from about 2500 to 5700 years BP. These dates show the apparent linkage between human activity in Alexandria and the observed sediment failure and mass movements in the harbours. Another study was conducted by Stanley and Bernhardt (2010) in the East Harbour of Alexandria; pollen and microscopic charcoals were examined in Holocene sediment core samples to assess whether the major environmental modifications recorded by the samples on Egypt’s coastal margin were influenced by natural, anthropogenic, or both factors. During the study four pollen-microscopic charcoal zones were identified. According to these, the earliest change occurred around 6000 years BP, during Egypt’s earlier Predynastic (Neolithic) period, coinciding with a lithologic break from sand to muddy sand. During this time, pollen indicates a transition to a much drier climate rather than effects of human activity. At 3600–2900 years BP, the second change in pollen occurred. This period was characterized by continued aridity and no lithological range in this core interval. Cereal taxa, agricultural weeds, grapes, and an abrupt accretion in microscopic charcoal suggest that human activity became dominant at least 700 years before the arrival of Alexander the Great in this 30
4. Palaeogeography
area. The aforesaid results articulate the transition from an environment controlled by the climate to one influenced both by climate and human activity. Finally, the third environmental alteration is dated c. 2300 years BP, which coincides with the construction of the Heptastadion by both Greeks and Romans, called by its longitude of seven (επτά) stadium, joining the Pharos Island to the city. From this time onwards, the harbour sediments indicate a nearly continuous record of anthropogenic activity. In addition, it is worth mentioning a geomorphological feature called ‘tombolo’, which was formed by Pharos Island, in Alexandria. The term tombolo is used to define a spit of sand or shingle linking an island to the adjacent coast (e.g. linking Pharos Island to the nearby coast). Generally, tombolos develop in shallow areas behind island barriers, where enough sediment supply together with wave and wind action are favourable to beach accretion. Tides swell, and currents serve as the transporting media, interacting with the island to set up a complex pattern of wave refraction and diffraction on the lee of the obstacle. At Alexandria, the tombolo is the legacy of a long history of natural morphodynamical forcing and human impacts. This rare coastal feature of Alexandria is one of the most celebrated tombolo examples, both in terms of its geological and archaeological scopes (Goiran 2001; Goiran et al. 2005). The proto-tombolo was a natural shallow sublittoral sand spit that already existed between the coastal area of Alexandria and Pharos Island, before the time of Alexander the Great and the construction of the Heptastadion. The accretion of the proto-tombolo took place between 6000 to 2400 cal. years BP, as the leeward wave shadow generated by Pharos Island was combined with high sediment supply after 3000 BP. During Alexander’s time the proto-tombolo was within 1–2 m of mean sea level (Marriner et al. 2008). During the 7th–9th centuries AD, the rapid submersion of great tracts of the tombolo was the result of tectonic collapse (Goiran 2001; Goddio et al. 2006). The coastal response of this catastrophic submersion was rapid, as the tombolo established a new equilibrium profile in balance with the high local sediment budget. According to Chalari (2007), during the 9th century AD Alexandria was struck by one or more oceanographic disasters (tsunamis, storms), which affected the eastern part of the tombolo and deposited coarse material. Based on bathymetry, sub-bottom profiling and side-scan sonar data, Papatheodorou et al. (2013) suggested that the tombolo of Heptastadion, the island of Pharos and the breakwater (Ridge A) had developed a natural system, almost encircling the harbour, preventing the entrance of high waves in inshore waters and reducing coastal erosion. The study of the palaeoenvironment of Maryût is based on the survey of two stratigraphic sections and two cores carried out in the most depressed part of the basin (Flaux 2012). The results of the studies of both macro- and micro-fauna revealed 31
Geophysical Phenomena and the Alexandrian Littoral
the presence of inorganic components as well as sedimentary deposits, which helped to identify four main phases: 1. The phase of sedimentation, in the central part of the lagoon, which came after a sedimentary hiatus, still puzzling. 2. The next phase is characterized by the total extinction of the macro-fauna and the creation of gypsum. This is confirmed by the creation of evaporite percussions due to the reduction in water supply. 3. The third phase is characterized by a new brackish environment according to the contained fauna. Compared to the previous phase, the basin became wet again. 4. As a result of previous depositions, this phase is characterized by post-deposition processes, which confirms the fluctuation of the coastline. According to the descriptions, three landscapes dominate: a huge lake, connected to the Nile, a marshy basin and a sebkha. Sedimentological analysis and analysis of historical data show two phases of drying, separated by a water distribution basin. This series includes three major phases of changes to the Maryût Basin. According to Cosson (1935), who explained the drying of Maryût, during the 12th century, three types of processes are described, at three different time scales (between the 2nd/3rd, 8th/9th, and 13th–16th centuries AD, the basin is connected to the Nile, where the water is brackish, while two drying phases are highlighted between the 9th/10th/13th, and between the 16th–18th centuries AD), which can explain the environmental history of the region: 1. A long-time period that saw the fall of the Canopic branch, from the Roman period to the 19th century, due to the gradual decline of the western margin of the Delta. 2. A period of several centuries, where two stages of drying of the basin are induced, as a consequence of the demographic and agricultural crises in the Behera area, which cause at least partial abandonment of the irrigation system. 3. The Nile’s multiannual volatility in annual and seasonal stocks, which are probably a key factor in the mobility of the coasts of the Maryût Basin, with a direct impact on land use.
32
5. Historical maps The earliest known mention of Alexandria on a surviving map goes back to c. 43 AD. On Pomponius Mela’s map of the world, ‘Alexandria’ is noted east of the Nile River Delta with the schematic representation of a high tower and the annotation ‘Pharos’. In the numerous copies of the Geography of Claudius Ptolemy, made c. 150 AD, the word ΑΛΕΞΑΝΔΡΙΑ is noted. The Roman road map of the 4th century AD, known to us from its mediaeval surviving copy, made in the 12th/13th century, and the Tabula Peutingeriana of Codex Vindobonensis 324, bear only a pictogram – the Pharos. On Eratosthenes’ map of the world, made c. 194 BC, Alexandria was certainly mentioned, but we have only literary reference and a 19th-century reconstruction of this lost map. There must have been other cartographic documents noting its position on maps of Africa and the Mediterranean, as well as specific views and plans of the Great City, which have in the meantime disappeared. In the very concise survey of views, bird eye views, plans, maps and charts of Alexandria and it ports that follows, ten cartographic documents have been selected among some 80 available. They range from the very first ‘aerial’ view annexed to Codex Urbinate 277, kept in the Vatican Library, to the first scientific map made in 1868 by Mahmoud Bey el Falaki, focusing on its ancient topography. They cover a period of six centuries and were selected for specific reasons explained in their description. All these cartographic documents are important for the understanding of the city’s ancient (as well as mediaeval) topography. The remains as marked are of great help for locating the city’s monuments, as well as the ‘hypodamian’ grid of streets, its fortified precinct, necropolises and ports. Over the centuries the walls have disappeared, and very limited remains of its monuments are visible; scant ruins are buried deep under Alexandrian soil, while those neighbouring the littoral have been submerged due to the combination of two phenomena: the rise of the Mediterranean and the subsidence of its coast. 33
Geophysical Phenomena and the Alexandrian Littoral
Veduta d’Alessandria Codice Urbinate 277 [1472] This is a view of Alexandria made in 1472 (Figure 13), annexed to a copy of the Geography of Claudius Ptolemy; there is another copy with minor differences kept at the Bibliothèque Nationale, Paris. It is obvious that the copyist had never been to Alexandria but was copying from an earlier map, using also information from travelers who had been recently there. The author misinterprets the standing obelisk of the Caesareum, drawn as a bell tower, and places a confusing structure on top of Diocletian’s Column, marked with the annotation ‘Sepulcrum pompei’, while an islet is placed inside the East Port, with six small structures and ten shoals at the approaches of this port; all indications that the map is drawn from an earlier cartographic document. At the time when the view was made those reefs were well under sea level. It should be stressed that the elongated islet will be shown as submerged on several of the plans and charts of Alexandria that will follow. The Fortress of Quaid Bey, which had just been built on the site of the ancient Pharos, is well drawn, while opposite, at the eastern entrance of the port, ancient Akra Lochias, on which a few years later the Pharillon will be constructed is completely deserted. The vestiges of the Heptastade are obvious, represented as a narrow pass connecting the mainland to Pharos Island. Three mosques, annotated ‘moscheda’, are shown, with no other buildings, where half a century later Ottoman Alexandria will develop extra muros. One of these mosques still stands; it is a small structure dating to the 10th century, supported by an ancient Roman column of red granite. Nearby, the ‘Porta della Dogana’ and the ‘Porta principal’ are the only gates marked. At the eastward extremity, outside the eastern walls, in today’s suburb of Chatby, two rounded structures with conical roofs are reminiscences of the Martyrium of St Mark and a church dedicated to St Catherine, which have disappeared; they are marked as ‘Sancti Marci’ and ‘Sanctae Catherine’. The two mounds of Alexandria, Kom el Dikka and Kom el Nadoura, the latter drawn exaggeratedly high, and with a surmounting ‘turris’, are well placed within the walled city. All the buildings, including several churches, are imaginatively rendered, as are the fortifications, all drawn in a Florentine style. The canal, entering the city under its southern walls, is drawn with a three-arched bridge and the annotation ‘Caligo flu’. In fact, this bridge (‘Calig’) is present on most of the plans to follow. Westwards of Pharos Island there are three islets – one featuring a tower. The importance of this view, the very first that has survived of Alexandria, is that it also raises questions as to the subsidence of its littoral.
34
5. Historical maps
Figure 13: Veduta d’Alessandria, Codice Urbinate 277, 1472 (Jondet, Pl. I).
35
Geophysical Phenomena and the Alexandrian Littoral
View of Alexandria from the Portolano of Piri Reis [1513] Contrary to the view of the Codex Urbinate, which draws from an earlier cartographic document and was made by a copyist who had not been to Alexandria, this view of Alexandria and of its two ports: the eastern, referred to as ‘Kiafir Liman’, the port of the infidels; and the western, known as ‘Garb Liman’, begun by an Ottoman admiral who knew well the city and its ports (Figure 14). It was made for the Piri Reis ‘portolano’ (portolan, pilot’s guide), and its topography is precise – as are the instructions to the mariners for whom this guide was compiled. .
The fortress of Quaid Bey is well represented, shown as ‘Liman Bourdji’, the ‘Port Fortress’; the smaller fort at the eastern entrance of the East Port is called ‘Haberi Kalesi’, the ‘Tower of Messages’. This smaller fort, marked on all maps to follow, is the Pharillon, and does not appear on the view shown in the Codex Urbinate, as it was built on the tip of the deserted ancient Akra Lochias at the end of the 15th or in the early 16th century. The jetty, which is present on all the cartographic documents to follow, is well marked near the Customs Gate. The column of Diocletian, the landmark of Alexandria, is correctly placed and labeled ‘Staro tasi’. The standing obelisk, the visible remains of the Caesareum is also drawn. The mounds of Kom el Dikka and el Nadoura are correctly placed, while a large mosque protruding in between those two mounds is possibly the Attarin Mosque. The walls are realistically rendered, as is the new Ottoman agglomeration that then started to develop on the reclaimed land where once the Heptastade connected Pharos Island to the mainland. The ‘Darsane’, the state arsenal, is placed on the eastern littoral of the West Port, not far from a small fortress, probably Fort Ada, which could still be seen up until a century ago, but which has now completely disappeared. The shallows of the East Port, as well as all the coast along the northern littoral of the former Pharos Island, are all noted in detail, and there are precise instructions in the text of the portolan as to the few shoals and reefs to be avoided. It should be noted that the oblong islet with six small structures on its top, as drawn on the Codex Urbinate, is marked on this view as a shallow. An interesting detail is the presence of an islet some 10 km east of Alexandria, on the course to ‘Ebugur’, Aboukir. This islet is the Gezireh Gabr el Kour, known today as ‘Miami Island’, and annotated as ‘Kürül Güdad- mezkür kayik limandir’. It formed, and still does, a haven for small boats, thus the mention of ‘Caique limandir’. There are 39 known versions of this portolano, and all the views of Alexandria differ. The one described is from the 1526 version from the Süleymaniye Library, Istanbul.
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5. Historical maps
Figure 14: Jean-Louis Bacque-Grammont, Michel Turchscherer, Piri Reis – Evliya Celebi, Deux regards ottomans sur Alexandrie, Centre d’Etudes Alexandrines, Alexandria 2013.
37
Geophysical Phenomena and the Alexandrian Littoral
Vray portraict de la Ville d’Alexandrie en Egypte [1547] Pierre Belon du Mans was a French medical doctor and naturalist who visited Alexandria during September of the year 1547. He wrote an account of his travels and accompanies his description of Alexandria with a carefully drawn view (Figure 15). It is the very first realistically rendered plan of the mediaeval city made by a traveler, and was to be copied, with modifications and updates, by several authors for some two centuries. Starting from the two ports, the western is mentioned as ‘Porto Vechio’, the ‘Old Port’, while at the entrance of the new one the shoal Le Diamant is noted as ‘Garophalo’. There are two forts guarding the entrance, the ‘Pharus’ (Quaid Bey) and the ‘Casteleto’, standing on the tip of today’s Silsileh, ancient Akra Lochias. It should be explained that the word silsileh stands for chain in Arabic, and this is certainly a reference to the heavy chain that once closed the port in ancient times, and possibly into the early Islamic period as well. The ‘Palais de Alexandre’ marks the ruins neighbouring the Caesarum in the vicinity of today’s Ramleh Station, where the obelisks, standing and fallen, are correctly marked. The ‘Porte du Caire’ is the Canopic Gate, the ‘Porta del Pepe’ (Pepper Gate) is Bab Sidra, and the ‘Porte de la Marine’ is the Customs Gate (marked as Porta della Dogana on other maps). Westwards we can read the annotations ‘Chateau Vieie’ and ‘Chateau Neuf ’ on the approximate location of the mound of Kom el Nadoura. Strangely, Kom el Dikka hill is not shown on this view. The canal enters under the northern walls and its ingress is marked as ‘Lentree du Nil’; it splits into seven branches, all ending in the sea. This slightly modified canal pattern appears on several of the cartographic documents to follow. Diocletian’s Column is drawn beyond the northern walls and marked as ‘Colonne de Pompée’, parallel to which a mosque stands, and is reproduced on other views and plans to follow. The walls and their fortifications are well defined and the annotation ‘Lac Mareotis’ bears an additional remark: ‘Lacd’eau doulce de moult grande estendue and de grand revenue en poisson’. Strangely enough the silted areas of the former Heptastade and Pharos Island are shown completely void of structures. So the author fails, for an unknown reason, to represent the new Ottoman agglomeration that had already been established on the land that extends today from the Midan to Amfoushi. The area east of the Canopic Gate is covered with palm trees and marked as ‘Fores de Palmiers’.
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Figure 15: Pierre Belon du Mans, Les observations de plusieures singularitez et choses mémorables, trouvées en Grèce, Asie, Judée, Egypte, Arabie et autres pays estranges, Paris 1553; Jondet, Pl. II.; S. Sauneron, Voyages en Egypte de Pierre Belon du Mans, IFAO, Cairo 1970.
5. Historical maps
39
Geophysical Phenomena and the Alexandrian Littoral
Plan M.P.nl-XLIX-43 of Alexandria from the Archivos General de Simancas [1605] The plan of Alexandria attached to documents E.1102-34 and E.1102-36 of the Archiveos General de Simancas, Valadolid, Spain is a unique document as it was produced not to illustrate a travel account or to be included in an atlas of maps, but was drawn by a spy, with the objective of supporting a proposed attack by a joint Christian fleet (Figure 16). The letters and the report are written in Catalan and were exchanged between the Marquis de Santa Cruz and the Viceroy of Naples. The feasibility for conducting such an attack is carefully described and was directed towards seizing the cargo of wheat transported yearly from Alexandria to Istanbul by an Ottoman merchant fleet. The aim was also to take a number of prisoners to be sold as slaves, and to loot the local population – the Jews are mentioned in particular as having wealth – and these intentions are proposed in the exchange of letters with shocking detail. It is known that, fearing such acts of espionage, the authorities had forbidden Christian merchants and travelers access to the walls, the mounds, or to walk freely around the ports. The spy in question here, most probably a Venetian resident merchant, meticulously drew his plan with 18 annotations, meant to assist the attackers in their incursion. It is proposed that they land off the eastern side of today’s Silsileh Promontory; enter the town through the ‘Porta de Rosetta’; after crossing the nearly deserted town, they would reach the ‘Piazza della mercantia’ and exit from the ‘Porta della Marina’ and attack the poorly guarded ‘gran fariglion’, the Quaid Bey Fort. The plan shows also the ‘fariglion piccolo’ at the eastern entrance of the port. Kom el Nadoura is marked as ‘Monte de guardia’, Kom el Dikka as ‘Monte de porta pevere’. ‘Burgo fuora citta’ is the Ottoman agglomeration. ‘Porta della Dogna’, ‘Monte de Guardia’, ‘Torre de Portovecchio’, ‘Torre Nova de Portovecchio’, ‘Torre della Polvere’, all for their gunpowder deposits, are carefully shown. The instructions that accompany the plan were meant to help the assailants reach and take control of the Fort Quaid Bey, while doing no harm to the Coptic Church of St Mark, marked with a large cross near the obelisk mentioned as ‘la guiglia’, as well as the ‘fondica de francesi’, on which a flag with the Fleur de Lys is flying. Some ruins in the centre of town are marked as ‘Palazzo di Sta Caterina’, these are the fictitious remains attributed to the palace of the father of St Catherine. There are three Turkish galleys berthed astern to the quay in the West Port, reserved for Muslim vessels, and several European merchant ships rest at anchor in the East Port. This carefully planned attack was never executed. A plague epidemic hit Alexandria in 1605/6, and this probably dissuaded the assailants, who eventually selected one of the other proposed Ottoman targets. 40
Figure 16: Harry E. Tzalas, The two ports of Alexandria, Plans and maps from the 14th century to the time of Mohamed Ali, Underwater archaeology and coastal management, Focus on Alexandria: 21–22. UNESCO Publishing, Paris, 2000.
5. Historical maps
41
Geophysical Phenomena and the Alexandrian Littoral
Alexandria, Vetustissimum Aegypti Emporium [1619] It is obvious that this view of Alexandria, drawn in 1619 and incorporated in the famous Jansson Atlas of 1657, is mainly based on that of Belon du Mans, but with additions, mostly spurious, gathered from travelers, pilgrims and merchants (Figure 17). The view has been repeatedly copied and manipulated for over a century and some 15 copies are known. The canals are exactly copied from the Belon view, but all other sites bear significant modifications and discrepancies. It is obvious that this is the result of compilations made by someone who had never visited Alexandria. Starting from the East Port, Quaid Bey Fort is shown, wrongly, as being smaller than the Pharillon, with the annotation ‘Garophalo’, a name given to the Le Diamant shoal. Across the port entrance we read ‘Guardia’ for the fort that stands on the tip of ancient Akra Lochias. Several Christian merchantmen, as well as small galleys, are seen moving inside and in the outer port. The West Port is much reduced in size and the author of this view tries to draw the ancient ‘Frahtos limin’, the enclosed military harbour, as a miniature enclosed basin, with railing. The city walls are represented double on the northern side and as single for the remaining perimeter. The copyist is confused with the position and number of obelisks, drawing three, instead of two, and all wrongly placed; one standing in the inner part of Akra Lochias, with a crescent on its top, marked ‘Obelisque’, and two others – one standing and one lying – near the Canopic Gate, mentioned as ‘Porte du Caire’. Next to this gate, inside the town, a little church is marked as being the site from where the body of St Mark was removed to Venice. This is obviously an error, as, according to tradition, the old church of St Mark (erected on the supposed site of the Evangelist’s martyrdom) stood outside the eastern medieval walls in the area called Boukolia. Taking the Canopic way and moving westwards, an imaginary ‘bassar’ is also marked as an enormous mosque. North of this imaginary building another imaginary structure, marked as ‘Domus Alexandri Magni’, certainly reflects the annotated ‘Palais d’Alexandre’ on Belon’s view. The centre of the town is filled with ruins, standing and broken columns, and various arches with a small, derelict structure marked as ‘mosque’ at the western end. Kom el Dikka is a bare hill; Kom el Nadoura bears a tower annotated as ‘castel noue’. Southwards, some ruins are marked ‘S. Catarinae’; it is known that some ruins were shown as the location of the martyrdom of Alexandria’s patron saint. Not far from that site we see a strange, small round building with a conical roof, surrounded by an octagonal wall, with a door on each side. It bears no explanatory annotation on this document, but on a French copy, entitled ‘Ancienne veue d’Alexandrie’, the explanatory note reads: ‘Le Scander leiu ou les Turks assurent qu’Alexandre le Grand est enterré’. This interesting remark is certainly reminiscent of the remarks by Massaoudi, Leon the African, and Marmol that Alexander’s body 42
5. Historical maps
was venerated in a small chapel; this is the only cartographic document showing that ‘turba’. Bab Sidra is marked as ‘Porta del pere’, a misreading of its real name ‘Porta del Pepe’ (Pepper Gate). Diocletian’s Column is placed correctly outside the walls, but too close to the shore and with the annotation ‘Columna Pompei in promontorio a Caesare erecta incredibilis altitudis et spissitudinis ex lapidib…’. The canal enters under the southern walls at the non-existant ‘Porta Nili’. Lac Mareotis is mentioned in the southwestern corner. A view of Alexandria made in 1686 by the Flemish O. Dapper is another version of the Jansson copy; it is entitled ‘De Stadt Alexandrie of Scanderik – La Ville Alexandria ou Scanderik’, obviously referring to Iskanderiyeh – the town of Iskandar, Alexander in Arabic. View of Alexandria by Vassili Barkij [1730] Barkij was a Russian monk who traveled extensively all over Greece and the Middle East, describing mainly places of the Greek Orthodox sites and making precise drawings of monasteries and churches, as well as locations referred to in the Old and New Testament. An accomplished artist, he draws in a naïve but precise style. His map of Alexandria is entitled Η Αλεξάνδρια ούσα κατά τους 1730 (‘Alexandria as in 1730’) (Figure 18). He resided at the monastery of St Sabba, known then as the ‘Hospitalio’ of the Greeks. He draws this as an impressive walled complex of buildings, marked as ‘Μοναστήριον του Αγ. Σάββα’. To the north he correctly places the hill of Κom el Dikka with a small mosque, probably that of Nabi Danial. West of St Saba he draws the Mosque of Attarin, the former church of St Athanasius, with no annotation. Also shown is ‘Το τότε πατριαρχείων των Φραγγών’ (‘The Patriarchate of the Franks’), i.e. the residence of the Catholic Bishop, later to become the Church of St Catherine. North of St Saba stands the obelisk of the Caesareum, marked as ‘H κολώνα της Κλεοπάτρας’ (‘The column of Cleopatra’). Nearby a ‘sakieh’ is moved by a donkey. Four standing columns mark the Canopic Gate, while a small, fenced structure bears the annotation ‘Των Ευρέων’ [sic] (‘Of the Hebrews’). This is the first time that the Synagogue in marked on a map of Alexandria. Its location on the Barkij view is not that of the ancient Synagogue located east of Akra Lochias, nor is this the location of the new Synagogue at Nabi Daniel street; it is placed diagonally northeast of the Attarin Mosque. Kom el Nadoura is drawn as a bare hill overlooking the West Port. The East Port is marked as ‘Ο Λυμνιώνας των Φραγγών’ (‘The Port of the Franks’), guarded by the Quaid Bey fortress and the Pharillon. Two large, three-masted vessels, and other smaller craft, are shown at anchor, and the interior pier is correctly marked. A large warship is anchored in the West Port with some smaller sea craft. The area is marked as ‘Ο λυνμιώνας των Τουρκών’ (‘The Port of the Turks’). East of Silsileh we see some fishing boats with lateen sails.
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Figure 17: Alexandria, Vetustissimum Aegypti Emporium, 1619.
Geophysical Phenomena and the Alexandrian Littoral
44
Figure 18: The wanderings of Vassili Grigorovich-Barskii to the Holy Places of the East from 1723 to 1747. Published by the Orthodox Palestine Society after a genuine manuscript prepared by Nikolai Barsukov, St Petersburg 1886–1887; see also Τόπος και Εικόνα, χαρακτικά ξένων περιηγητών για την Ελλάδα, 18ος αιώνας, Olkos, Athens, 1979.
5. Historical maps
45
Geophysical Phenomena and the Alexandrian Littoral
Diocletian’s Column is correctly drawn outside the southern walls. These walls are drawn in fact as they then were, in a derelict condition at several locations. The interest of this panoramic view is that it realistically renders the desolation of the ancient and mediaeval town within the walls, where we only see a small group of houses not far from the Canopic Gate, while the Ottoman town extra muros is shown densely built. Barkij also made separate drawings of the Caesareum obelisk standing, as well as Diocletian’s Column. His views of the Nile at Cairo, Rashid, Rosetta, as well as drawings of the so-called ‘Well of Joseph’ and ‘Spring of Moses’, in the Sinai, indicate that Barkij traveled extensively to other Egyptian locations as well as Alexandria. Description de la ville d’Alexandrie, telle qu’elle étoit du terms de Strabon, par M. Bonamy [1731] This is the very first attempt to draw a plan of ancient Alexandria based on the relations of reliable ancient authors, including Strabo, Diodore, Josephus, Plutarch and others. Bonamy was a member of the Societé des Inscriptions et Belles Lettres of Paris, and accompanies his mémoire with a map (Figure 19). That Bonamy never set foot on Alexandrian soil is a certitude, as he erroneously places Diocletian’s Column (marked as ‘columna Pompeii’) and the ‘Serapeum’ inside the city walls at the western extension of the Via Canopica. He had certainly access to several earlier plans and views of Alexandria: the two main arteries, the Via Canopica, and what was thought to be the road of the ‘Soma’, today’s Rue Nabi Daniel, are well drawn. The fact that he places the ‘Paneum’ at Kom el Dikka, and annotates nearby ‘Sema seu sepulcrum Regum’, may well be the starting point of the erroneous positioning of the tomb of Alexander the Great in the crypt of the Nabi Danial mosque. The ‘Caesareum’, but not its obelisks, is rightly marked at the northern end of this road, on the shore of the ‘Magnus Portus’, near the ‘Navalia’. The Heptastade is shown connecting the ‘Pharus Insula’ to the mainland separating the ‘Portus Eunosti’, on its western side of the ‘Magnus Portus’. At its entrance, in between the ‘Turris Pharus’ and ‘Acrolochias’, some shallows are properly marked as ‘Cautes’, and the submerged Diabathra is also correctly drawn at ‘Lochias Promontorium’, a part of the ‘Domus Regia’. All the eastern sector of the city is correctly marked as ‘BRUCHION’ and ‘Interiores Regia’. The ‘Gymnasium’, the ‘Musaeum’, the ‘Bibliotheca’, and the ‘Theatrum’ are arbitrarily located, while the ‘Judaeorum habitation’ is correctly marked on today’s Chatby and Ibrahimieh shores. The eastern walls extend approximately to the modern Sporting neighbourhood, a plausible hypothesis ; the east ‘Suburbium’ has the ‘Hippodromus’ wrongly marked, but what was known as Caesar’s Camp is correctly marked as ‘Nicopolis’. The canal and ‘Lacus Maraeotis’ are very approximately shown beyond the southern walls. 46
Figure 19: M. de Bonamy, Mémoire, Description de la ville d’Alexandrie, telle qu’elle étoit du tems de Strabon, Paris, 31.8.1731.
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Geophysical Phenomena and the Alexandrian Littoral
Carte et Plan du Port Neuf d’Alexandrie by Capt. Frederick Lewis Norden [1738] and Carte particulière de la Vielle et de la nouvelle Alexandrie et de ses Ports [1738] Captain Frederick Lewis Norden traveled extensively in Egypt and Nubia and made a map of Alexandria as well as a plan of its eastern port; in fact this can be considered as the very first nautical chart of the feature once known as ‘Megas limin’, ‘Portus Magnus’, and later ‘Mina el Sharki’. We will first concentrate on the chart and its panoramic view of the city as seen when entering the East Harbour (Figure 20). Both forts are well positioned: West, Quaid Bey, is mentioned as ‘Citadelle’, with Le Diamant marked and an annotation for another reef reading ‘ce rocher est a 12 a 13 pieds sous l’eau et n’est pas de grande etendue’. Two parallel lines are drawn from the spot of two dangerous reefs in the direction of Diocletian’s Column and a nearby minaret. The attention of the mariner is drawn by the references: ‘La Colonne de Pompée ouverte suivant la direction de cette ligne est une marque de ce rocher qui est 15 pieds sous l’eau’, and ‘La Colonne de Pompée justement ouverte avec la vielle Tour est la marque de ce rocher’. East, the ‘Petit Pharillon’ is shown on the tip of Silsileh Promontory, with some rocks being the submerged remains of the ancient Diabathra. Shallows and rocks are seen obstructing the central entrance, and a depth of ‘2 pieds’ is noted. It is on those shallows that, in the early 20th century, the modern protective Al Majah jetty was built. Some lead soundings appear on the chart and shallows are also drawn with the annotation ‘hors de l’eau’, and a depth of ‘5 pieds’ at the approximate location where an islet, with some structures, is shown on the view of Codex Urbinate 277. All the area around the shores of today’s Amfoushy is marked with extended shallows. Looking at the panorama of the city and starting eastwards, some few, small buildings and the walls are drawn, as well as what was then known as the ‘Roman Tower’ overlooking today’s site of Gare de Ramleh. In between that tower, which was in fact part of the ancient fortifications, and the standing obelisk, the large building shown is the Greek monastery of St Saba. We then have the continuation of the course of the walls along the littoral, and Kom el Dikka is drawn as an impressive hill. The minaret protruding parallel to Diocletian’s Column could be that of the Attarin Mosque. Another seven minarets are marked on the western littoral, with buildings witnessing to the dense structure of the Ottoman city extra muros. Kom el Nadoura protrudes above the location of today’s ‘Tikka’ restaurant, where four little boats are tied astern to a jetty. The second plan shows both harbours, the ‘Port Vieux’ and the ‘Port Neuf ’, with the ‘Grand Pharillon’ and the ‘Petit Pharillon’, as well as a detailed outline of the walls of 48
5. Historical maps
the ‘Vielle Alexandrie’. The ‘Colonne de Pompée’, the ‘Obelisque de Cléopatre’, and then ‘St. Mark’, ‘St. George’, ‘St. Catherine’ are all indicated. ‘Citernes’ and ‘Porte de Rosette’ are the only annotations for the old town. For the ‘Nouvelle Alexandrie’ only the building of the ‘Douane’ is marked. Half a century after Norden’s visit, Konstantin, a Russian prelate, visited Alexandria and wrote (in Russian and Greek) a story of the ancient city. This author used, without mentioning the fact, Frederick Norden’s two maps to illustrate his account. What is most interesting is that to the laconic annotations of the Danish captain, the Kiev archimandrite included his own remarks and brings some minor changes and additions which are worth commenting on. Konstantin of Kiev ‘Θέα του λιμένος της Αλεξανδρείας’ [1795] When reproducing the chart of the East Port, Konstantin was not interested in providing instructions for mariners, nor does he reproduce the depth soundings; he also omits the parallel lines meant as warnings of the hazards when entering the port (Figure 21). He places the annotation on Cape Lochias, ‘Remains of the Ptolemy’s’ deposit of books’; the obelisk has the description ‘Obelisk in memory of Cleopatra’; and repeatedly we have the ‘remains of ruined buildings’. Most interesting is Konstantin’s drawing, in the shallows of the area extending from the ‘Roman Tower’ to the then ‘Customs’ Gate’, numerous scattered architectural elements. An obvious observation confirming that when the sea was calm the submerged remains of the Timonion, Antirodos, and other ancient buildings of the Royal Quarters, were well visible. All his annotations are in Russian. Konstantin of Kiev ‘Χάρτα της Άλεξανδρίας και των δύω αυτής λιμένων’ [1795] Of interest also are Konstantin’s annotations on the map of ‘Ancient Alexandria’ (Figure 22): noted are the ‘Rosetta Gate’ (then an ‘artificial reservoir’); probably the El Nabi cistern; St Saba is marked as the ‘Monastery of the Greeks’; St Mark at Missala as the ‘Monastery of the Copts’; and ‘six columns’ stand on the course of the Via Canopica. The ‘semi-abandoned mosque’ is certainly the Attarin Mosque, which was then in a derelict condition. It was pulled down a few years later and rebuilt in its present shape by Mohamed Ali. ‘Bab Sidra Gate’ is correctly marked, as is the ‘Column of Pompeii’. The western burial grounds have the annotations ‘Subterranean ruins’, ‘Subterranean sanctuary’, and ‘Necropolis’.
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Geophysical Phenomena and the Alexandrian Littoral
Figure 20: Carte et Plan du Port Neuf d’Alexandrie by Capt. Frederick Lewis Norden [1738] and Carte particuliere de la Vielle et de la nouvelle Alexandrie et de ses Ports [1738].
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Figure 21: Konstantin of Kiev, Θέα του λιμένος της Αλεξανδρείας, 1795.
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Geophysical Phenomena and the Alexandrian Littoral
Figure 22: Frederick Lewis Norden, Travels in Egypt and Nubia, London 1757; Jondet, Pl. XII; Konstantin, Ancient Alexandria, Description of the town during the visit of Archimandrite Konstantin, published in Moscow (1803) ‘at the expense of the well-known Greek Maecenas, the Zosima brothers’.
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Carte générale des côtes, rades, ports, ville et environs d’Alexandrie dressée par M. Gratien le Père [1798] This is one of the most interesting maps produced by the French savants of Bonaparte’s ‘Expédition de l’Egypte’, with many details related to the topography of ancient and mediaeval Alexandria (Figure 23). The outline of the restricted medieval walls, that were to be pulled down in 1882, is correctly shown. The ‘Porte de Rosette ou d’Abou Kir’, also mentioned as ‘Porte Canopique’ and the only gate in use at that time, is well marked. The Canopic Way runs from this gate to the ‘Eunostus Portus’, more precisely to the inner ‘Kibotos portus’ or ‘Frahtos Limin’. The Via Canopica cuts at right angles with today’s Nabi Denial Street; those were the only ancient streets visible at the time. The ‘Magnus Portus’, the ‘Megas Limin’ of the Greeks, is densely annotated with depth soundings, revealing that a large area was silted up with extended shallows. Shallows, reefs and shoals also mark its entrance, making it a most hazardous shelter for vessels of any size. Today’s Silsileh Promontory is marked as ‘Lochias’ and ‘Akra Lochias’, with ‘le Pharillon’ its tip. The ruins of that fortress existed up to the mid 20th century, when the whole area was reshaped for military purposes. The submergence of that ancient promontory is well indicated and shallows mark the ancient Diabathra. We can read the annotation ‘Port des Rois’, ‘Anti Rhodos’ and ‘Timonium’ in the shallows of the littoral; the presence of those submerged ancient remains was confirmed by the recent underwater archaeological surveys. The eastern part of the littoral of that port, at today’s Mazarita, is marked with the annotation ‘Ruines’, then we read ‘Posudoman’ (sic) at the site of today’s Ramleh Station, where once stood the Roman Tower, which was part of the ancient fortifications. Further west, ‘deux obelisques’ and ‘Cesarium’ correctly mark the location of the largest of the Alexandrian temples. The totally deserted eastern part, extra muros, forming an empty triangle, is correctly marked as ‘Bruchion’. This location was completely devastated from AD 272, following Aurelian’s campaigns against Zenobia, Queen of Palmyra. The Old Jewish cemetery that was there, and still exists, is omitted. The ancient eastern suburbs known as Pros Eleusini Thalassa, Nicopolis and Julioplis are deserted, marked as ‘côte couverte de ruines’. Moving westwards, ‘Pharus’ and ‘Le Phare’ mark the exact location of the fort of Quaid Bey, with the rock of Le Diamant just protruding. Numerous shoals are noted on the northern part of ‘Pharus Insula’, and Ras el Tin promontory is correctly marked with the annotation ‘Cape des Figuiers’. The shallows that follow are annotated ‘Passe des Djermes’ and ‘Petite Passe’. It should be recalled that those shallows played a decisive role in the military events that were to follow the Napoleonic landing on Alexandria. 53
Geophysical Phenomena and the Alexandrian Littoral
Not daring to enter the West Port, because of the restriction of those two passages, the French fleet, after landing troops at the ‘Anse du Marabout’ (near today’s Sidi Krer), moved eastwards to the Bay of Aboukir where, from the 1st to the 3rd of August 1798, it was annihilated by the British fleet under the command of Admiral Horatio Nelson. The coast around the West Port has annotations such as ‘des Catacombes’, ‘Temple souterrain’, ‘….couverte de ruines’, and the ‘Necropolis’ accurately identifies the vast western burial site. The former location of the Heptastade, and where Ottoman Alexandria extended extra muros, is correctly marked as ‘Ville Moderne’, while the ancient town within the walls is labelled ‘Rhacotis’, the area allocated since its foundation for the native population. However the annotation ‘Serapeum ruines’ is incorrect, as the Serapeum was outside the mediaeval walls, where stood the landmark of Alexandria ‘la Colonne’ (Diocletian’s Column). The ‘Panium’ is also wrongly placed. The ‘cirque’ and ‘hippodromus’ mark the visible ruins of a stadium that has since completely vanished. The dotted line showing the ‘enceinte presumée de l’Ancienne Alexandrie’ is very near to the probable course of the ancient walls. The space that was once the heart of ancient Alexandria is deserted, and we read the words ‘ruines’, ‘citerne’, ‘colonnes’, etc. Kom el Nadoura is drawn as a small hill with no annotation, as Kom el Dikka, probably the ancient ‘Paneum’. The ‘Gymnasium’ is arbitrarily placed south of the Via Canopica. All the southern section of this map is marked as ‘Mareotis Lacus’ with the annotations ‘Portus Flivius’ and ‘Moles’ on its littoral. We can also trace the canal going along Lake Maryût’s northern shore, entering the old town under the southern wall and flowing into the West Port. There are three bridges shown on that canal – one is the ancient Kadig. The area of ancient Boukolia is marked as ‘Eleusine’. Plan of the city harbours and environs of Alexandria, by Captain Smyth (1825) This is the most complete survey of the approaches of the two ports of Alexandria (Figure 24). Several charts with scarce or denser soundings preceded Captain Smith’s work (Melchien, 1699, Jondet Pl. IX; Massy, 1699, Jondet Pl. X; De la Garde, 1713, Jondet XI; Norden, 1738, Jondet XII; Pocoke, 1743, Jondet XIV; D’Anville, 1766, Jondet Pl. XV; Déscription de l’Egypte, 1798, Jondet Pl. XVII and XXI; Le Pere, 1798, Jondet XVIII; Capitaine Barré, 1798, Jondet XIV; Captain Walsh, 1802, Jondet XXVII and Le Saulmier de Vauhello, 1834, Jondet Pl. 1834); except for that last none bear so dense soundings covering an area of circa 15 square km extending from Cape Marabout (Dekhela) to Chatby. All the reefs, shoals and shallows are attentively marked on this precious aid for mariners entering and sailing off the two ports. It also greatly helps understanding the subsidence phenomena of the Alexandrian littoral by comparing depths with those of todays.
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Figure 23: Jondet, Pl. XVII. There are two other maps of Alexandria and its wider area created by the Bonaparte Expedition: Carte des Cheneaux d’Accès au Port d’Alexandrie, 1798, Jondet Pl. XIX and Carte d’Alexandrie et de ses environs d’Agamy à Aboukir, 1798, Jondet Pl. XVIII.
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Geophysical Phenomena and the Alexandrian Littoral
It should also be stressed that prior to Bonaparte military expedition to Alexandria the Western port was exclusively used by Ottoman vessels and taking soundings was prohibited. Foreign vessels were allowed to the Eastern Port that was partly silted; large ships had to anchor in the outer harbour. The lack of a proper chart of the approaches of the Western port had tragic consequences on the Bonaparte expedition as M. d’Anville plan used by the French bore not a single sounding of the Western Port, nor of its approaches. Avoiding that uncharted hazardous area, the French fleet anchored westward in the Anse du Marabout, todays Dekhela on the 1st July 1798. Unable to remain at anchor in that exposed bay, after the military landing the fleet moved eastward to the protected Bay of Abou Kir where a month later it was annihilated by Nelson’s fleet. Should the French vessels had entered the Wester Port, they would have been well protected by the guns of Fort Quaid Bey. Let’s briefly describe that chart: from East to West an elongated ‘Pharos Bank run parallel to the littoral North of the entrance of the Eastern Port; numerous soundings mark the shallows on both sides of the Silsileh and the contour of the ‘New Port’. (El) ‘Hassan’ is marked as a reef. The position of the ‘Diamand Rock’, is illustrate with more details in an enlarged drawing, framed separately as are two mini-illustrations: The Pharos castle and a panorama of the city with its landmarks: the hills and Diocletian column. The sea area along the ancient ‘Pharos island’ is also marked with numerous soundings as well as all the wide space between the extra muros ‘New City of Alexandria’ and Dekhela. The old city within and outside its mediaeval walls bear numerous annotations and the words ruins is repeated. The ancient Necropolis of Chatby is marked as Sepulchres, Lochias as Pier in ruins topped by the Pharillon. The Roman Tower marks the space of today’s Ramleh station, the hills of Kom el Dikka and Kom el Nadoura are Cretin and Caffareli. Pompey Pillar, Road to Rosetta, the Harem, English Consulate, Pharos isle, Old Castle, Convent, Synagogue, Parade Grave and other topographical annotations witness to the abandoned agglomeration that was, only a few years later, to resurrect as a modern city. Plan d’Alexandrie par Mahmoud Bey el Falaki [1866] Were it not for the interest of Napoleon III in writing a History of Julius Caesar, where he drew an analogy between the politics of the Roman Emperor and his own, as well as those of his uncle, the most important plan of ancient Alexandria would not have been realized (Figure 25). The Emperor wrote to Khedive Ismail asking if a map of ancient Alexandria were available, as he wanted to research into the topography of the ancient city in order to follow the background to the hostilities that set Caesar and Cleopatra VII against her brother, Ptolemy XIII, in 48/47 BC. On enquiring, the Khedive was told that there were various old maps of Alexandria but none were to be considered as reliable topographic sources of the ancient city. Wanting to please the 56
Figure 24: Plan of the city harbours and environs of Alexandria, by Captain Smyth (1825).
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Figure 25: Mahmoud Bey, Mémoire sur l’Antique Alexandrie ses faubourgs et environs, Copenhague, 1872.
Geophysical Phenomena and the Alexandrian Littoral
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French Emperor, Ismail instructed Mahmoud Bey, who held the title of ‘Astronomer’ (El Falaki), but was actually an engineer who had studied in Paris for eight years, to do whatever was necessary to produce a satisfactory plan. Aware of the scale and scope of such an enterprise, Mahmoud Bey accepted the challenge, as this was a unique opportunity to discover hidden and submerged ancient remains. Specialized scientists, and the complex technical assistance and instruments needed, were put at his disposal, as well as the large team of workers required for the excavations. ‘El Falaki’ was not an archaeologist but he was well aware that the visible remains of ancient and mediaeval Alexandria alone were insufficient to achieve his goal and that numerous trenches would have to be dug to reveal the ‘hypodamian’ grid of the ancient streets, and also bring to light once more the remains of its magnificent monuments that had long ago disappeared. There were several excellent general maps of Alexandria, scientifically realized, at El Falaki’s disposal, including, to mention just two, Savary’s of 1785, used by Bonaparte for his attack on Alexandria, and the excellent cartographic documents made by the French savants of the Expedition de l’Egypte in 1798. The visible ancient remains that would be his landmarks were Diocletian’s Column, marking the ruins of the Serapeum, the two obelisks of the Caesareum, several visible ruins that dotted the city, the extended burial grounds (the Eastern and Western necropolises), as well as the standing, although restricted, mediaeval walls. El Falaki made two maps: the Carte de l’Antique Alexandrie et de ses Faubourgs and the Carte des Environs d’Alexandrie. The latter extends from Taposiris Magna to the Gulf of Abou Kir and includes all of Lake Maryût and Lake Edfou. The maps were ready by 1866, but fate took a hand and Napoleon had to face the growing Prussian threat, and in 1870 was defeated and captured at the Battle of Sedan; he died in exile three years later. In 1872, El Falaki published, in Copenhagen, his map of Ancient Alexandria with a Mémoire. The most important feature of this map is the grid of the ancient streets. Having as a reference the visible Via Canopica and today’s Nabi Daniel Street – marked as R5 on his plan – he opened hundreds of trenches and discovered sections of nine streets running parallel to the shore and a further twelve in a north–south direction. They all intersected at right angles, in the original ‘hypodamian’ design, as first applied at the very foundation of Alexandria. El Falaki carefully traced the vestigial walls of the mediaeval town, an invaluable testimony, as they were to completely disappear twelve years later. He also locates, based on some scant remains, the assumed perimeter of the much more extended fortifications of Hellenistic and Roman times. We now know that his proposed course for the Heptastade is not absolutely right, as a recent survey 59
Geophysical Phenomena and the Alexandrian Littoral
by the Centre d’Etudes Alexandrines has revealed its correct direction, however his positioning of the ‘Timonium’, ‘Antirrhodus’, ‘Cape Lochia’, and the ‘Port Privé des Rois’, were all confirmed by recent underwater surveys. The 132 pages of El Falakis’ Mémoire give a detailed description of the city’s topography; so our study will be limited to a concise appraisal. Careful soundings were conducted in the ‘Magnus Portus’ that help our understanding of the subsidence of the city’s littoral. Le Diamant is correctly drawn off the ‘Phare’, as well as other annotations: ‘Maçonnerie à fleur d’eau’ and ‘Rocher sous l’eau’ at the port entrance. There is also an extended pattern of submergences marked as ‘Rochers’ and ‘Digue’ in the area of the ‘Diabathra’. The littoral of the Eastern port – that will be greatly modified a few decades later by reclaiming parametrically a sea area of over 100 m in width for the opening of the Corniche – is precisely marked. We can take a brief tour around ancient Alexandria using this plan, with the ‘2 Obélisques’ of the ‘Caesarem’ as a starting point. The ‘Temple de Neptune’ is hypothetically placed, as is the ‘Théatre’, in the correctly marked ‘Palais Royal’ and ‘Palais interieurs’. Moving towards Kom el Dika, mentioned as ‘Paneum’, El Falaki erroneously places the ‘Soma’, probably influenced by the tradition that placed the burial of Alexander in the crypt of the Nabi Danial Mosque. The ‘Museum’ is also arbitrarily located west of the ‘Soma’. Three mosques are well sited : the ‘Eglise St. Athanase – Mosquée’ is the Attarin Mosque, the ‘Mosquée de milles colonnes’, and the ‘Mosquée d’Amrou’. The ‘Serapeum’, with its ‘Colonne dite de Pompée’, is also rightly marked. The ‘Rue Canopique’ extends eastwards beyond the mediaeval Rosetta Gate (where the ‘Gymnase’ is slightly misplaced) and reaches an hypothetical ‘Porte Canopique’ at today’s suburb of Sporting. The eastern littoral is void of any annotation; we only note the assumed position of the ancient walls extending eastwards along the coast, and the ‘Chateau des Césars’, marking the then extended ruins of a Roman camp at Mostapha Kamel. Two small Islamic funerary chapels (turba) are marked as ‘Santon de Chatibi’ and ‘Santon Sidi Gaber’, giving the modern names to these two suburbs. There is the annotation ‘Temple’ for some ruins marking an inland area, an elevation with the annotation ‘Eleusis’, and an ‘aqueduct souterrain’ adjacent to the canal. Four bridges lay on that canal, following the northern shores of ‘Lac Maréotis’ which reaches to the eastern walls and ends at the ‘Port d’Eunoste’, through the ‘prolongement du canal ou 1er aqueduc souterrnain’. All modern archaeological plans of ancient Alexandria are based on El Falaki’s, including the very important ones updated by Tassos Neroutsos (Figure 26) and Giuseppe Botti.
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Figure 26: Alexandrie ancienne par Neroutsos Bey (1888).
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6. Historical references For many centuries, Alexandria was the major port city in the Eastern Mediterranean (Figure 1a), being established on the northwestern coastal margin of the Nile Delta by Alexander the Great in 332 BC, on his way to the temple of Amoun at Siwa, and further developed by his successors, the Ptolemies, who reigned until 30 BC (Mahmoud-Bey 1872; Fraser 1972; Empereur 1998). The site was known to mariners sailing the waters of the southeastern Mediterranean prior to the 1st millennium BC. The port of Alexandria became the most important in the Eastern Mediterranean during the rule of the Greeks, Romans and Byzantines (Mahmoud-Bey 1872; Fraser 1972; Empereur 1998; Goddio et al. 1998; Goddio and Clauss 2006; Hirst and Silk 2004). It is generally suggested that the population of Alexandria rapidly increased to hundreds of thousands during the city’s early Hellenistic history under Greek rule. During the time of the Greeks, Alexandria had an extensive and well-defined street grid designed by Alexander’s architect, Dinocrates (McKenzie 2003; 2007). Building works of all descriptions increased considerably during the rapid expansion of Alexandria by the Greeks and contributed to the sediment and infill accumulating in the basin (Goddio et al. 1998). The city was underlain by hundreds of cisterns, some of which were large and strikingly complex, built to maintain an adequate supply of fresh water for most of the year (Empereur 1998). Small hills were formed by large refuse heaps in several parts of the city, while rubbish and waste were drained from streets via sewage canals that fed conduits surrounding the expanding metropolis (Rodziewics 1995). The building phases included major projects both on land and in the sea (Bernard and Goddio 2002; Empereur 1998; Goddio et al. 1998). This city and marine construction activity continued during the post-Augustan Roman era. The population had diminished substantially by the time of Arab occupation in the 7th century AD, and subsequently the number of inhabitants fluctuated, but remained generally low until around the 1840s and the period of Muhamad Ali, who understood the importance of Alexandria and began to reconstruct and revive it (Stanley et al. 2006). Of great importance also was the small island of ‘Pharos’ (Odyssey, 354–357), 62
Figure 27: Map of the East Harbour of Alexandria showing archaeological sites (based on Goddio et al. 1998).
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Geophysical Phenomena and the Alexandrian Littoral
located approximately 1 km north of the present-day city. Because of its upwind side it afforded shelter for mariners seeking refuge from storms and other dangers. Maritime traders, such as Minoans, Phoenicians, Philistines, and perhaps Egyptians too, were probably familiar with Pharos Island during the New Kingdom and later Dynastic periods – at least one thousand years before Alexander the Great reached the area (Jondet 1916; Marazzi et al. 1986; Weill 1919). According to indications in Homer (Odyssey, republished 2003), Strabo (Geography, republished 1917–1932) and others (Jondet 1916; Weill 1919), the stretch of coast on which Alexandria was built was settled before Alexander’s arrival. Occupation in this area before Alexander is also proved by several archaeological sites (Egypt Exploration Society 2005), such as those along Lake Maryût to the south (Rowe 1954) and the Nile Delta coast to the east of Alexandria (Stanley 2005; Stanley et al. 2007). During the period from about 2100 to 1800 years ago, as the city expanded, Greeks and Romans constructed a causeway and aqueduct system, referred to as the ‘Heptastadion’. This construction linked the city of Alexandria to Pharos Island. The Heptastadion was built over a shallow, pre-existing topographical eminence, the ‘tombolo’ (see Chapter 4, Palaeogeography), which rose from the embayment floor to almost near sea level. Initially the bridges at the Heptastadion construction acted as a partial barrier to the natural flow of water that had prevailed between the originally undivided western and eastern parts of Alexandria Bay prior to the 3rd century BC. The Heptastadion had a length of seven stadia, about 1200 m, and over many centuries and various natural processes was progressively raised and widened by the accumulation of sediments (Hesse 1998). Consequently this construction formed the longer, West Harbour, called ‘Eunostos’ and the much smaller East Harbour, called Megas Limin (Great Port) (Stanley and Bernasconi 2006; Papatheodorou and Chalary 2008; Hesse 1998; Goiran 2001; Goiran et al. 2005) (Figure 27), resulting in diminished flushing effects by seawater on sediments, and accumulating consequently in a much smaller basin (Mostafa et al. 2000). The two harbours had a total length of about 14 km when they were connected, prior to the construction of the Heptastadion. Today, these ports are separated: the West Harbour became the city’s major commercial port in the latter part of the 19th century, with extensive sea-wall and dock constructions that altered the harbour considerably (Jondet 1916). Rhakotis, or Râ-Kedet, was a pre-established settlement on Egypt’s Mediterranean coast before Alexander the Great founded Alexandria in 332 BC, on the site where Alexandria is located, before the 4th century BC and prior to Ptolemaic occupation. However, there is surprisingly little information as to its exact location or the origins of the inhabitants (Baines 2003; McKenzie 2003; Ashton 2004). By some historians, Rhakotis (Pausanias, v. 21, Pliny, v. 62) is considered to have been either a fishing village of little significance, a more substantial walled centre, or possibly a fortified 64
6. Historical references
settlement (Fraser 1972; Empereur 1998; Baines 2003; McKenzie 2003; Ashton 2004). Nowadays, a city south of the Heptastadion is called Rhakotis (Rowe 1954), but no archaeological evidence to date has revealed the presence of an early pre-Alexandrian site. Additionally, modern Alexandria has almost entirely buried the remains of earlier habitation (Empereur 1998).
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7. The decline of Alexandria and physical disaster As already mentioned, Alexandria experienced great glory during Hellenistic and Roman times, almost up until the end of the 3rd century AD. Later, many political and, especially, religious movements had their origins in Alexandria, leading to the various persecutions that disaffected the population with Roman rule and created the conditions that ultimately led to the city’s fall to the Persians (AD 616) and then the Arabs (AD 642). After its occupation by Amr-Ibn-Al-As in AD 642, the great city of Alexandria was shadowed by a series of complicated events until its almost utter disappearance. Apart from its conquest, the city suffered considerable destruction from environmental and geological phenomena. Characteristic indications of these are found in the texts of Arab historians and travelers who wrote their impressions from Alexandria from the 8th to the 15th centuries. Eminent among these was Ibn Abd Al-Hakam and his work Futuh Misr (‘Egyptian Conquests’). Abdel Hakam came from the Al-Fustat, the area of today’s old Cairo. Another celebrated traveler, historian and geographer was Al-Masudi, who wrote his famous book Mouroutz Al-Dahab (‘Pastures of Golden Knowledge’ or ‘Golden Meadows’) between the 9th and 10th centuries AD. In the 11th century AD, the most influential works were those of Al Baghdadi, a compatriot of Al-Masudi, who visited Alexandria at the time of Saladin. In the 12th century, Ibn Joubair from Andalucía wrote Al-Rihla[tu] (‘The Trip’). A similar, valuable work was written by Ibn Battutah in the early 14th century AD, who referred to the large-scale destruction of the city in the 14th century. Also in the 14th century, Al-Makrizi, in his three volumes entitled Al-Khitat (‘The Planning of the Cities’) describes the knowledge available in his time and refers to the earliest major destruction of Alexandria, in the 4th century AD, from an earthquake and tsunami. A further writer was Al-Asyuti, who penned a travel/geographical treatise that referred especially to earthquakes in the Middle East (Ambraseys et al. 1994; Zerefos et al. 2008). 66
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Through these Arab chroniclers, travelers and writers, it is clear that until at least the 10th century Alexandria maintained its glory, even though it underwent significant changes stemming from the interventions of Arab conquerors. Moreover, the wonder of the buildings of Alexandria is referred to by the geographer Strabo, as well as by many other visitors to Hellenistic Alexandria. In AD 642, Amr-Ibn-Al-`As, the conqueror of Alexandria, sent a letter to the caliph of Medina, Omar Ιbn Al-Hattab (634–644 AD), in which he stated that he had conquered ‘a city with 4000 theaters, 4000 gardens (monua), 4000 spas, 400 clubs, and 12000 grocery stores. It had shining marble buildings which reflected so much light that by day they blinded the inhabitants, and in the evening one could see even with little light.’ Some 350 years later, Al Muqaddisi, in AD 1000, writes in his Guide to Alexandria that ‘Al-Iskandariyya is a delightful city’. In approximately AD 1200, Ibn Joubair in his famous work The Trip states: ‘First of all is the beauty of the place of the city with its broad buildings, to an extent which we have not seen in any country or city with larger roads, higher buildings, nor older and richer. Its cosmopolitanism is incredible, and its markets are perfectly full, and in abundance and festive. The noteworthiness is its placement, how it is built either below or above the earth, its buildings are so old and so resilient. A remarkable thing with the construction of the city is that the buildings that are located beneath the surface of the earth are like those that are above the ground and are even better and more solid, because the waters of the Nile enter underground beneath the houses.’ In the early 19th century, the famous Chateaubriand mentions that the only historical buildings seen when approaching Alexandria are Diocletian’s Column (wrongly known as the ‘Column of Pompeii’) and Cleopatra’s Obelisks (‘Needles’). In her work Passing through Egypt, Fanny Pratt wrote in 1843: ‘It does not resemble any of the countries I have seen. It is very brown and flat. The Column of Pompeii stands isolated and can be immediately seen by anyone entering the port, as well as the Palace of Mohammed Ali, industries, the shipyard and some windmills, twelve in a group… Alexandria is nothing more than a city of ruins, except for the buildings of Pasha that have been reconstructed.’ In 1803, Napoleon’s engineer, Gratien Le Père, disembarked in Alexandria and reported the extensive débris of ceramics, glassware and marble fragments. Le Pere (1812) writes that he encountered a ‘field of ruins’, from which two small hills protruded that had also been formed by the piling up of all kinds of débris on the orders of Sultan Selym in 1517, as reported by Leon Africanus. Le Père describes the phenomenon of alluvia and the rising of sea levels, and invoked the memories of the French Consul Maillet (1692–1718), who mentions that the city is located on sedimentation. He wrote that the sedimentation continues, and that in the 26 years Maillet was there the sedimentation 67
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increased by 40 ‘steps’. It is therefore certain that from the time of Ibn Battuta in the early 14th century AD until the time of Le Père in 1803, and from Le Père until today, major changes occurred along the northern shore of the Nile Delta, and especially in Alexandria (Zerefos et al. 2008). Among these changes are the disappearances of the ancient sites of Timonion, Antirhodos Island, the Royal Port installations, which were located at the East Port, the Vassilia, the Royal Quarters, the Diabathra, and the Temple of Isis Lochias on the promontory of Akra Lochias, nowadays called Silsilah. Today, Timonion, Antirhodos, and the Royal Port installations constitute underwater reefs covered by a thick layer of sludge, where marine antiquities and treasures are hidden and began to be identified by marine archaeologists only in the last two decades. The disappearance of the old port pier was discovered by the engineer Gaston Jondet in the early 20th century, northwest of Pharos Island. In his work Alexandrea ad Aegyptum, Breccia (1914) believes that the majority of Ptolemaic monuments are to be found under the sea, as described very clearly in the notable work Description de L’Egypte (1812). This latter work details the apparent landslip along the coastal region of the Nile Delta, leading the maps used by Jondet (1916, 1921) a century later to show the evolving phenomenon of the landslip on the northern coast of the Delta. Jondet (1916) believed that the area of the Lake Maryût salt-marsh suffered no major landslip (‘Al-Houbout’), as occurred in Alexandria, as the mud deposits in the Maryût region were relatively shallow and more durable than the corresponding formations located in the Alexandrian Gulf. As mentioned by Jondet (1916), Al-Makrizi was the first to write about the inflow of the Mediterranean into Alexandria, inferring that this first occurred in the period before the Arab conquest. Indeed, after the large earthquake in the 4th century AD, which is described by Al-Makrizi, and especially after the huge tsunami that struck Alexandria, it seems that the submersion (landslip) of a large area of ancient Alexandria accelerated. In a recent scientific work, Shaw et al. (2008) have calculated that the height of the tsunami created by the earthquake described by Al-Makrizi exceeded 20 m (Shaw et al. 2008). Such a phenomenon seems to have been repeated in the 12th century, as mentioned by Jalal Al Din Al-Souyouti (or Al-Asiouti/Al-Souyoyti) in his memorable work on the history of Egypt and Cairo. The year 702 of Hegira (AD 1303), witnessed the greatest earthquake and the destruction was most severe in Alexandria, compared to all previous earthquakes and disasters suffered by the city. As Al-Asiouti mentions, ‘the sea rose up, reaching the middle of the town; it drowned livestock and people, while ships were moved inland and countless houses and people disappeared beneath the ruins.’ In this context it is common to refer to Al-Makrizi’s Al-Khitat (‘The Plans of the Cities’), in which he states that a large earthquake struck in the time of Constantine 68
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and the sea rose and hit locations, including many churches in the city and collapsing 17 towers along the great walls. Al-Makrizi continues that ‘the sea has since continued ceaselessly, swallowing little by little whole sections of the city’. Al-Makrizi also mentions the Mamelouk Sultan, Baibars (1260–1277), whο was the first of the Mamelouk Sultans to be interested in Alexandria, visiting it four times. Every time he left behind him monuments that historians have recorded and reported. On his second visit in early AD 1265 (664 Hegira), he ordered the removal and cleaning of the sediment that had almost covered whole segments of the channel of Alexandria; on his fourth visit in 1274, he had the lighthouse restored and repaired. Al-Souyouti also mentions that the side of the lighthouse facing the sea had collapsed, and the dockyard (‘Al-Rasif ’) enclosed by the lighthouse was ready to fall. This is supported by the reference Ibn Battuta makes during his visit in AD 1325. The traveler records seeing one of the sides of the lighthouse having collapsed. Visiting the city again twenty-five years later, in 1350, he saw that the ruins were such that one could not enter nor climb from its gate. There is a vast amount of documentation on the history of Alexandria and its harbours, including works by Mahmoud-Bey (1872), Jondet (1916; 1921), Empereur (1998) and Goddio (1998), among others. However, detailed systematic archaeological investigations in the East Harbour began only about a decade ago. Damage to the City of Alexandria inferred from earthquakes, tsunamis and other natural disasters, recorded by the historians, has been catalogued by Nicholas Ambraseys (2009) in his seminal study, Earthquakes in the Mediterranean and Middle East: a multidisciplinary study of seismicity up to 1900. Recent studies on the vulnerability of the Alexandria coastal area to tsunamis have used numerical simulations to model plausible tsunamis and wave amplitudes generated by earthquakes along the active tectonic Hellenic subduction zone and Cyprian tectonic Arc (Eckert et al. 2012; Valle et al. 2014). The susceptibility of Alexandria to tsunamis has been studied, among others, by Shaw et al. (2008), based on the risks inferred by the event that occurred on 21 July, 365, and by Hamouda (2005) on the destructive impact of the one on 8 August, 1303. According to Eckert et al. (2012), an approximate tsunami frequency of 1/800 year was estimated for the region of Alexandria. This frequency was calculated taking into consideration the only two historical tsunami occurrences that caused significant damage to the city; however, it was not possible for this frequency to be associated with a specific tsunami runup. A recent study by Synolakis and Kalligeris (in preparation) simulates the AD 365 earthquake and shows that the tsunami generated did probably strike Alexandria.
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As a conclusion, although Alexandria experienced phases of decline and expansion, such as that following the Arab conquest of the 7th century AD and the present expansion phase with its more than four million inhabitants, this famous city remains a major commercial harbour and the largest population centre in the southeastern Mediterranean.
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8. Modelling tsunami vulnerability1 The Mediterranean Sea has witnessed a few large tsunamis that we know of in the historic record, starting from the Bronze Age tsunami triggered by the circa 1628BC eruption of the Thera volcano. Tsunamigenic earthquakes in the Eastern Mediterranean have been described starting by Galanopoulos (1960), Ambraseys (2009), Salomon et al. (2007), Shaw et al. (2008), Vale et al. (2014), England et al. (2015), and Howell et al. (2017). As discussed earlier, most notable among these events are that of 21 July 365AD whose associated tsunami inundated coastal sites in North Africa, the Adriatic, Greece and Sicily, and that of 8 August, 1303AD (inferred to have occurred SW of Rhodes and E of Crete) which also caused widespread damage in the Eastern Mediterranean (Shaw et al. 2008), England et al.(2015). Based on partitioning of the seismic and aseismic convergence observed for the AD 365 event in southwestern Crete to the entire Hellenic subduction zone, Shaw et al. (2008) estimated that similar events may occur about every 800 years, with the last one taking place in 1303AD (Ambraseys and Synolakis 2010). These inferences are suggestive that a large event may be overdue. In this it regard, is it important to understand the vulnerability and quantitatively describe the impact of tsunamis so as to better infer what may have occurred during historic events described by chroniclers. As Vale et al. (2014) write referring to Wdowinski et al. (2006) ‘the Cyprian Arc is located at the east of the Hellenic Subduction Zone and forms the plate boundary between the Anatolian plate to the north and the Nubian and Sinai plates to the see https://www.google.com/search?rlz=1C1CHZL_enGB830GB830andei=kv2RXN_uHrHixgOkt5a4CAandq=%22Hist orical+tsunamigenic+earthquakes+in+the+Eastern+Mediterranean+have+been+described%22andoq=%22Historical+tsu namigenic+earthquakes+in+the+Eastern+Mediterranean+have+been+described%22andgs_l=psy-ab.3...30473.39620..40 851...0.0..0.182.1414.16j1......0....1..gws-wiz.......35i302i39.JyQadm8ORb8] [Academia: Tsunami simulations for historical and plausible mega-thrust events originating in the Eastern Mediterranean Sea]
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south. Although the Cyprian Arc has experienced little seismicity over the last century, it is also a source of tsunamigenic earthquakes. According to the catalog of Ambraseys (2009) and references therein, the largest known tsunamigenic event along the Cyprian Arc appears to have occurred on 11 May 1222, and appears to have been accompanied by a leading-depression N-wave (Tadepalli and Synolakis, 1996). Estimates of tsunami inundation, rely on numerical simulations of tsunami evolution, which in turn rely on specification of suitable initial conditions, in other words, on descriptions of the seafloor deformations that created the waves. If one had tens of events on record, as for example are known for Japan in the last two millennia, it is not impossible to attempt probabilistic studies and estimate how often large tsunamis exceeding a certain threshold strike the region of interest. However, in the absence of defensible recurrence rates for any events, the only way of studying the exposure to tsunamis is to look at plausible ‘worst-case’ megathrust (Mw > 8) tsunamigenic events that could occur along the Hellenic and Cyprian Arcs, and which could impact Alexandria, as done by Vale et al. (2014). Vale et al. considered segments of the Hellenic and Cyprian Arcs and constructed scenario earthquakes, whose locations and source characteristics mimic historic events, and whose size and location are inferred from descriptions in earthquake catalogs. These earthquakes were used as initial conditions in the modelling described next. 8.1 Simulating possible tsunamis in Alexandria To evaluate onland tsunami inundation, numerical simulations were performed using the numerical model known as the ‘Method of Splitting Tsunami’ (MOST), most recently described by Titov et al. (2016). In MOST, tsunami evolution is simulated in three phases: generation, propagation and inundation. The generation phase considers a finite dislocation representing an earthquake source, then uses the formalism proposed by Okada (1985) to compute static deformation of the ocean floor. The propagation phase solves the depth-integrated non-linear shallow water (NLSW) equations in two spatial dimensions and in time. The numerical solution of these equations uses a finite-difference algorithm that splits the NLSW equations into a pair of two one-dimensional evolution systems. Finally, the inundation phase simulates the shallow water behavior of a tsunami by extending the solution of the NLSW equations on land, using a moving-boundary scheme to estimate tsunami runup onto dry land (Titov and Synolakis 1998). MOST has been benchmarked using standard guidelines described in Titov et al. (2016) and is used operationally for real time warnings by the National Weather Service. 72
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Tsunami evolution requires bathymetric and topographic data. We used the GEBCO-08 grid, a global 30-arc second grid publicly available. High-resolution bathymetry data were also incorporated in the model, when and as available. MOST uses up to four nested grids – the version we used had three, with resolutions of grids A, B and C 0.0292 arc-degrees (3000 m), 0.004867 arc-degrees (500 m) and 0.00081 arc-degrees (84 m) respectively. There are two reasons for this practice. One is to try ensure consistent resolution in terms of grid points per wavelength, during the computation In deeper water, the basic tsunami wave train wavelength are shorter than in more shallow waters. Ideally, the grid resolution should vary continuously, but this is not yet possible, because of the difficulties in continuously re-gridding results. Two, even as of the time of this writing in 2019, it is not computationally realistic to calculate the evolution of a long wave from its generation to its ultimate destination thousands of kilometres away, at very high grid resolution. Besides, it wouldn’t add much to physical realism of the predictions. Bathymetric features of subgrid scales in deeper water do not substantially alter the evolution of the waves. 8.2 Scenario megathrust tsunami sources We considered four plausible megathrust earthquakes and calculated the resulting tsunamis. The scenarios are named S1, S2 and S3 and are located along the Hellenic subduction zone while S4 along the northwestern Cyprian Arc. The details of these scenarios are described in Vale et al. (2014). In the case of S1, a detailed description has been reported by Shaw et al. (2008). For S2, S3 and S4, for which no direct historic analog exists, we use scaling laws (Geller 1976) to derive appropriate parameters to describe the earthquake sources and the appropriate Okada (1985) style model. As Emile Okal has argued in Vale et al. (2014), the inherent assumption is that the largest earthquakes in the study area follow seismic similitude and this may be legitimately questioned, since several major earthquakes, such as that in Tohoku in 2011 (Ammon et al. 2011; Fujii et al. 2011; Pollitz et al. 2011) and the Cretan event of AD 365, as modeled by Shaw et al. (2008) and Flouri et al. (2013), deviate from the scaling laws as they are understood at the time of this writing. For S2, we used a larger slip that Mitsoudis et al. (2012) and a slightly different location; as per Vale et al. (2014), it is equal to 10 m over a 190 km segment of the eastern Hellenic Arc. The specific location was selected to produce the maximum potential runup along the western Nile Delta region. The source parameters for S3 are similar to S2, with the addition of a variable-slip source mechanism with six fault planes, corresponding to a magnitude 8.3 earthquake. 73
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Along the Cyprian Arc, source S4 is derived from Wdowinski et al. (2006), whose work shows convergence, with significantly more normal azimuths and faster rates along the northwestern part of the Cyprian Arc. S4 is a complex fault with 11 m slip in the four central planes and a 5 m slip in the four outer planes. As with S3, S4 is comparable to one of the maximum-slip fault patches in the Sumatra earthquake of 2004 (Subarya et al. 2006). 8.3 Tsunami simulation results Results from the simulations are presented in Figures 28, and 29, as in Vale et al. (2014). Figure 28 shows maps of maximum tsunami heights over the entire eastern Mediterranean basin, for the four scenario events. The motivation is to identify the regions in the basin, which not only may have done so in past centuries, but may spawn destructive tsunamis for Alexandria in the future. Out of a population of 5.2 million, it is estimated that a few hundred thousands may be at risk, and without an effective tsunami warning system, tens of thousands could die. As Vale et al. (2014) argue, for S1 a strong lobe of directivity is aimed at the coast of Cyrenaica, Libya (Ben-Menahem and Rosenman 1972, Kanoglu et al. 2012), while a secondary lobe, presumably controlled by shallower bathymetry is aimed towards the Peloponnese in Greece. Maximum amplitudes (zero-to-peak) in the 2–3 m range are projected along the eastern Libyan and Egyptian coasts. In the case of S2 (eastern Hellenic Arc event with uniform slip and Mw 8.4), as in Figure 28b, the directivity lobe is aimed directly towards the Rosetta promontory of the western Nile Delta near Alexandria. The simulation results for a variable-slip source (S3) at the same location indicate that the effect of variable slip is concentrated in the near-field; the effect becomes negligible in the far-field along the Egyptian coast, at a distance where the tsunami essentially integrates the seismic source, whose details become largely irrelevant to the final wave amplitude. This is a classic manifestation of a principle equivalent to St Venant’s in elasticity theory, that is, for similar sources or disturbances, the details of the source do not matter in the stress field farfield. Source S4 (located in the Cyprian Arc, as in figure 28d) features a lobe of directivity aimed at the east Libyan coast and, symmetrically, on the eastern coast of the Gulf of Antalya, Turkey. It affects Alexandria less. In summary, it appears that tsunamis generated by earthquakes between Rhodes and Crete are more likely to severely affect Alexandria compared to those from other regions in western Crete and along the Cyprian Arc. 74
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Figure 28 Maps showing the maximum wave heights over the entire eastern Mediterranean basin for four different scenarios, S1, S2, S3, and S4. Figures are identical to those from Vale et al. (2014).
8.4 Tsunami impacts at Alexandria Figures 29 a, b and c show the wave evolution at different depths and locations for scenario S1, so that our results can be compared with Shaw et al. (2008). They show what are time history of surface elevation records, or what would have been recorded had a wave measuring buoy been deployed at that location. The wave heights we infer (Figure 29a and b) are about twice as high as those inferred by Shaw et al. (2008), shown in Figure 29c. The wave amplitude estimates at the virtual gauges shown are relatively insensitive to the details of the slip distribution on the fault. Such amplitudes exceeding 1m at 20m water depths would inevitably lead to severe structural damage along the coast. We are reminded here of the 2004 Indian Ocean tsunami which devastated Phuket, but its height was about 2-5m at 10m depth, about 1 mile offshore, and the wave broke as it approached the coastline. The size of this wave is similar to the wave that hit Phuket, although far more detailed modelling is needed to see how far inland the wave will penetrate and how many residents are now in harm’s way, unfortunately it appears that there are hundreds of thousands, particularly because of the possibility of overland tsunami flow from the Mediterranean into Lake Mariotis. 75
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Figure 29: Plots of the wave height in relation to time that would be observed a) in the area of Pharos, and b) off the coast of Alexandria. (Nikos Kalligeris, private communication). For reference, we reproduce here the graph by Shaw et al. (2008) of the wave height against time in the area of Pharos, by the AD 365 earthquake.
In conclusion, our analysis shows that large tsunamis originated in the region between central Crete and Rhodes have the potential of severely impacting Alexandria. While even the approximate location of the AD 1303 earthquake is not known, beyond that it was triggered somewhere east of Crete, it is clear that the resulting tsunami had crushing impact in the city. This tsunami is likely the cause for its demise – Alexandria never recovered from this event until the 20th century.
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9. Coastal zone In the coastal area of Alexandria there is numerous archaeological evidence (burial sites, quarry activities, ancient building remnants), as well as geomorphological features, that reveal a complex evolution of the coastal zone. In the following sections some of this evidence is examined, testifying to submergence at different sites of coastal Alexandria (see Figure 1). 9.1 Silsileh In the area of Silsileh (the ancient Akra Lochias promontory), more particularly 550 m northeast of the west tip of Silsile and 1100 m seaward from the Chatby coast and the El Hassan reef (31o 13'N, 29o 54'E). This reef is located at a depth of 17 m with some parts at about 14 m. As mentioned above in Chapter 3 (Evidence of offshore subsidence in Alexandria), the mean subsidence rate for the last 200 years is about 30 mm/yr in the region of the El Hassan reef. 9.2 Chatby On the plan of Alexandria in Codex Urbinate 277 (1478), as well as on the plan of the Piri Reis Portlan (1513) and the annex to the manuscripts of Archivos General de Simancas (1605), a portion of the ancient promontory of Acra Lochias, which was part of the Royal Quarters, appears to be deserted except for the small fort (the Pharillion, marked on its tip in the latter two documents). That promontory, known today as Silsileh, is represented on all Alexandrian maps, plans and drawings made from the mid 17th century to the early 1800s as a series of islets, just at sea level, interconnected by means of two makeshift wooden bridges. The largest part of the eastern ancient promontory is today submerged. Had it not been for the constant dumping of ancient material, starting with blocks and rubble in the early 19th century when a new fort was built at its inland extremity, the whole promontory would have been totally submerged today. 78
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Large blocks with hieroglyphics have been found underwater, at depths ranging between 3.5–4 m, 70 m east of today’s concrete blocks around Silsileh, and 100 m from the present shore. It is assumed that they belong to an in situ ancient building. Furthermore, many architectural elements were found at depths of 8–9 m. The removal of these structures that once stood in the Silsileh took place in Late Roman times, when the Romans reused the architectural material and today the only remains are the blocks that they left and were gradually submerged. All the large architectural elements of Greco-Roman and early Byzantine times were found in the Chatby area. East of Silsileh, ancient, large architectural elements have been dumped into the sea, while in the 1960s modern concrete blocks were also placed on the seabed in an attempt to form a buttress to the action of the waves and keep the eastern part of the East Port protected. It is difficult to determine which of the nearly 400 ancient blocks and slabs – some bearing Pharaonic inscriptions and carvings – are in situ, which have been moved by the action of the waves, and what material has been transported from the nearby coast. These blocks rest on the seabed at depths varying from 4–8 m and are regularly covered and uncovered by sand. However, taking into consideration their great weight, it is certain that at least four oversized architectural elements made of red granite lay in situ or were very near where they originally stood. This is the tower of a gateway (Figure 30) and its monolithic flight of steps, a monumental base for a large statue, and the threshold of an oversized door. The gateway and its tower and steps most probably formed part of the Temple of Akra Lochias, while the threshold could have been part of Cleopatra’s Mausoleum. Akra Lochias was razed during the war of Aurelian against Zenobia, Queen of Palmyra in AD 272; it remained deserted and was left outside the Late Roman, Byzantine and Islamic fortifications of the town. Some of the scattered architectural remains on the Lochias promontory and adjacent coast were used at different periods for different structures, while some, as mentioned earlier, were used as filling material in an attempt to keep Silsileh above sea level. There are also many broken artifacts that can be found on the seabed around the neighbouring Chatby Casino. The area of the sunken Akra Lochias was well delimited during a survey conducted by the Laboratory of Marine Geology and Physical Oceanography, Department of Geology of the University of Patras, with the use of side-scan sonar and bottom profiling (see plan). It is worth noting that not one single stone anchor dating from Islamic times was found in this area. The few anchors retrieved from the Chatby area were all found just beyond its eastern boundaries. This is a clear indication that between the 11th– 13th centuries AD – or perhaps even later – the site of ancient Acra Lochias was either at sea level or its submergence was minimal, and not even small fishing boats with shallow drafts had access to it. 79
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Figure 30: A section of the gateway and tower.
On the Chatby coast, east of Silsileh, there stood a large religious complex, including a basilica built on the Martyrium of St Mark, from the late 4th century. It was destroyed in 1219 by Melik el Kamel, a nephew of Salah el Dine, who feared that it could be used by attacking Crusaders (Neroutsos 1888). However, it is likely that its ruins were possibly visible for almost another four centuries, as shown on the Codex Urbinate (Jondet, 1921) and the Simancas documents (Tzalas 2000). In the maps, the basilica is depicted halfway between the Akra Lochias promontory and the Chatby necropolis. Today, only a few sherds can be found, some with smoothed edges on the surface and some with sharp edges in the deeper sand layers. The HIAMAS surveys revealed two Early Christian capitals, a most interesting Sygma table, a few columelae, and some architectural elements lying on the seabed. These finds, as well as hundreds of sherds found in trenches opened on the Chatby beach, date to the 5th and 6th centuries AD, and bear witness to the presence of that Early Christian complex. There are also numerous earlier remains of paved areas, walls and foundations in the shallows. Nevertheless, on satellite imaging, a semi-circular underwater formation, 600 m in diameter and extending east of the ‘Chatby Casino’, was noted on the seabed. Its diameter (base) runs parallel to the coast and lies at about 650 m from the Silsileh 80
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Figure 31: Traces of the submerged semi-circular and ‘Π’ formation at Chatby from French satellite image, courtesy of the Centre d’ Etudes Alexandrine.
promontory. From a submerged depth of a few centimetres on the sandy littoral, it slopes gently, reaching a 10–12 m depth at 600 m from the shore, its northernmost limit. At that point the satellite imaging shows another linear formation, shaped as ‘Π’ and measuring approximately 400 x 550 m. That semicircular formation has raised interest and was checked superficially during many HIAMAS campaigns to ascertain whether the feaure was natural or man-made (Figure 31). All this sea area is scattered with ancient remains, as noted by several scholars in the 19th and early 20th century (Description de l’Egypte 1809; Mahmoud-Bey el Falaki 1872; Breccia 1919; Adriani 1966; and a personal note by Miezyslaw Rodziewicz). This was also confirmed during the 2014 HIAMAS campaign by the geologist N. Evelpidou, who, despite diving in limited visibility, noted man-made sandstone, rock-cut structures. Notwithstanding the constant swell and movement of sand, which creates turbidity and reduced visibility over the entire area, this site will have to be surveyed in detail: the extensive ancient remains require careful geophysical as well as archaeological investigation and interpretation. In addition, Chatby is thought to be the necropolis of Hellenistic times (3rd century BC), which is now under water. 81
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9.3 Ibrahimia Off the coast around the suburb of Ibrahimia there is a large reef located at a depth varying from 10 m to 14 m, probably the remnants of the kurkar ridge II. More than 80 stone anchors datable to Islamic times (10th – 11th centuries AD) and from small fishing vessels, were found in rock cavities during the HIAMAS surveys; most were successfully raised. The lead parts of a large, composite Late Hellenistic or Early Roman anchor (1st century BC/1st century AD) were also found and raised from a depth of approximately 9 m. It is assumed that the anchor belonged to a merchantman of about 30 m in length. It is surprising how such a large vessel, with a draft of over 2 m, could anchor in waters that were shallow at the time. If we assume a difference of 5 m in the sea level of the reef, by considering the 2 m of eustatic sea level rise during the nearly 20 centuries elapsed, and 3 m of submergence for that same period, then the anchor was dropped in shallow waters of about only 4 m deep. Opposite that reef in the shallows, a large stone quarry, of an intricate pattern, including inner canals, was visible until a decade ago, when it was completely obliterated by the widening of the Corniche coastal road. The remains of that quarry were also affected when the Corniche was opened at the beginning of the 19th century. HIAMAS had the opportunity of surveying the entire area of that quarry before its disappearance. The Aktitis stone quarry is an ancient one, exploiting the soft stone of the area; today it lies underwater. There are deep cuts into the submerged soft stone, 300 m long and parallel to the shore. The quarry was first worked in Ptolemaic times, in the middle of the 4th century BC. It was just beside the city walls and it is possible that burials also took place here, simultaneously with quarrying activities, at undetermined times. The type of soapstone extracted can be found all along the eastern and western coasts of Alexandria, from Abu Qir to Mex, and was probably also used for the fortifications of the first Ptolemaic town. The quarry width is roughly 300 m and follows a gentle slope to the sea. The depth at the shore is only 50 cm, while it reaches over 2 m at its northern limits. Then there is a sudden 4 m depression, an abrupt fall, when one reaches the northern boundaries. The remains of six shaft tombs were visible on the shore, just at sea level, evidence that burials coexisted with quarrying activities. Quarrying was discontinued at an undetermined period as a result of submergence, as is witnessed by a number of large quarried blocks found abandoned at the bottom of some extraction basins. The Ibrahimia coast was noticeably higher than any other location of the eastern littoral, and when the quarry was first exploited, probably in Ptolemaic times, the land was some 6 m above sea level. Thus, a sea level rise of 2 m may be supposed, considering a land subsidence of 2–3 m; hence the extremity of the quarry facing the sea would originally have been at least around 2 m above sea level. 82
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9.4 Sporting Beach At 250–300 m seawards of the shore at Sporting, the compact seabed is probably evidence of the submerged surface of the carbonate ridge (Ridge II, at a depth of 6–12 m), representing a palaeoshore of around 8–10 m in depth. The continuation of the submerged ancient necropolis is found in the Sporting area; in general, the necropolises from Chatby to Lesser Taposiris were quarried in undetermined times. Neroutsos (1875) gives an interesting description of the burials, visible along the coast of Ramleh and in the shallows,that were systematically destroyed. In the area of Sporting there are two noteworthy underwater features (Figures 32, 33a, b): One of these, 40–45 m from the shore, is an E-W rectangular rock cutting (56 x 18 m), divided into three separate parts. The central one has equally spaced cuttings on its lateral part, resembling shallow loculi every 0.80 m, 1 m wide and 0.6 m high at a depth of 1–1.5 m, and similar cuttings on the northern and southern side but not on the western one. Recently, while diving, N. Evelpidou located small basins (2 x 2 m) and connected small channels inside the formation, and suggested the possible presence of fish tanks, based on the observed characteristics. Between the rectangular structure and the shore, there are remains of stone quarrying. The second noteworthy feature is represented by two deep, semicircular cuttings into the bedrock. One is located west of the rectangular feature just mentioned, and to
Figure 32: The Sporting coast and submerged structures (photo: The Greek Mission).
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Figure 33: Underwater ancient remains at Sporting (photos: The Greek Mission).
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the south there is another; the two of them forming a distorted circle. On the 19thcentury maps, the ‘Tomb of Stratonice’ was placed in this area (Neroutsos 1888), however these remains have yet to be studied. It is known that Stratonice of Libya, wife of Archagathus (a Ptolemaic official) constructed a temple of Isis and Serapis, dedicated to her uncle Ptolemeos II Philadelphos and her grandmother Verenice I, although at an undefined site. The underwater feature (c. 2–3 m) at Sporting could also be a fish tank, as indicated by the existence of small channels connecting different basins (Evelpidou et al. 2018). It is also possible that the offshore reef could have offered some protection to fish tanks here. The structure requires further study. 9.5 Moustafa Kamel The Necropolis of Moustafa Kamel includes monumental burials of Hellenistic times. Today the Early Ptolemaic Necropolis of Chatby and the Necropolis of Sidi Bishr represent the visible remains of the former extended Eastern Necropolis along the coastline. Inland in this region, isolated Roman villas, such as the Nicopolis Roman Encampment, existed. Today there are no remains of the grandiose ruins of the Nicopolis structures; they were almost intact until the middle of the 19th century and were then robbed of their material for modern building constructions (Neroutsos 1888). 9.6 Gleemenopoulos Beach 2.5 nautical miles offshore of Gleemenopoulos, two large canons (18th/19th century AD) were recovered from the bottom of a reef. 9.7 Sidi Bishr The uninhabited islet of El Asafra lies at a distance of about 370 m off the shore at Sidi Bishr 1, the beach of the Alexandria Corniche Hilton, northwest of the Sidi Bishr promontory (310 15' 53'' N, 290 58' 48'' E). This feature is approximately 93 x 20 m, and is obviously a remnant of kurkar ridge I. Seaward of the Sidi Bishr promontory, to the northeast, there are two lines of concrete blocks, 260 and 60 m long respectively, placed on a line of reefs. These two reef lines have connected Gezira Gabr el Khour (Miami Island) to the Bir Massaoud promontory for centuries. On the cadastral map of 1932–1949 some of the contemporary reefs at sea level are marked, evidence indicating the rapid subsidence of Alexandria’s littoral zone over the last 60 years. 85
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9.8 Miami Island – Gezira Gabal el Khour (Gabr el Khour) Miami Island is located 120 m from the shore of Sidi Bishr 2, and has an oblong shape of 200 x 60 m. The surface of the island is formed of karren fields. On the island, there are man-made deep cuttings and burial remains, indicating that it was part of the vast Sidi Bishr necropolis. The water depth varies greatly from 4–5 m west of the island, to 8–9 m to the east. At a distance of 150 m north of the island there is a reef with marks of deep quarrying at a depth of about 2–2.5 m. Many anchors dating from Islamic times (11th–13th centuries AD) have been found to the north. On the island’s southwestern part there is evidence of possible fish tanks. As a continuation of Miami Island to the west, there is another reef 150 x 32 m in size, which was probably also a part of the vast Sidi Bishr necropolis. The description of Miami by Piri Reis (1525) in the early 16th century in his portolan (Kitabi Bahariya 1525) is worth special mention, as he described a rock being visible on the west side of the island towards the sea, where a ship could pass between the shore and the rock. By passing that rock in a direction towards Abou Kir, one could see two visible rocks near to one another. These rocks are still visible today on the way to Abou Kir, indicating that no significant subsidence has taken place in the area since the 16th century. While Piri Reis names the island ‘Kürül’, the modern ‘Güdad’ means a ‘bubbling, small canal’, which could be the noise made by the water in the deep manmade channels, which even today make such sounds). At the southeast part of Miami Island, a fish tank construction is visible (Evelpidou et al. 2018). Miami island itself acts as protection for the fish tank from storms. Similar to the other investigated fish tanks along the wider Alexandria coastline, the Miami feature is rock-cut (see Chapter 10, Fish tanks). A chain of cement blocks, some 200– 300m from the shore, has been placed, probably as a wave break, on the 2-km long beach east of the Gabal el Khour, i.e. Miami Beach (Sidi Bishr 2) and the subsequent Mandara Beach. There are no archaeological features along the site of the blocks. Small reefs (31o 16' 44'' N, 30o 00' 10'' E) are to be found inside this chain of blocks. 9.9 Montazah Montazah is located in Maamourah, a wide, open wide bay (c. 3 km) dotted with several islets, about 14 km east of the East Port of Alexandria. Maamourah lies between the small bay of Montazah (c. 400 m wide) to the west, and the promontory of Abou Kir to the east, after which the vast gulf of Abou Kir (c. 33 km wide) extends. The Gulf of Maamourah and the Montazah Bay comprise mainly one gulf, embracing an oblong island (perpendicular to the coast, c. 420 x 100 m) near its western end called ‘Geziret Halawa’. It was King Farouk (1936–1952) who connected this island to the shore with a bridge and called it 86
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the ‘Island of Dreams’ (Geziret el-Ahlam) (or ‘Tea Island’). Sedimentation later settled around the bridge’s foundations, thus forming a spit with two bays. Breccia (1926) reports that ancient remains and a Roman cemetery were discovered on the Montazah promontory when the ‘Haramlek Palace’ was constructed, and mentions that the whole region of Maamourah was possibly a Roman summer resort. The Montazah fish tank complex is made up of many large tanks cut in the rock crowning the northern edge of the island, where there is much evidence of cutting and constructions (see Chapter 10, Fish tanks). 9.10 Maamourah The uninhabited islet of Ghireisha (33o 18' 22'' N, 30° 02' 17'' E) lies about 500 m off Maamourah coast; it has some 550 x 65 m in size and probably constitutes a remnant of kurkar ridge I. Maamourah, which stretches from the Montazah promontory to Cape Abou Kir, was studied and described at the beginning of the 20th century by Ev. Breccia in 1926. Breccia describes the many ruins of archaeological sites seen during his time working along the Maamourah coast, especially from the site opposite Ghireisha Island to Cape Abou Kir, the ancient Zephyrion. He refers, among other features, to many cisterns, swimming pools, large and small basins, hot springs, on the coast or not far away inland, mostly on the sites of probable nearby villas. In some cases he also refers to fish tanks (see Chapter 10, Fish tanks). Breccia refers to that site, in general, as the City of Canopos, although he mentions that there are doubts as to its precise location. Stanley et al. (2001; 2004b) and Goddio (2004) have recently confirmed by underwater research that the two historically referred to and flourishing cities of East Canopos and Herakleion were submerged in the Abou Kir Gulf. 9.11 Abou Kir The Canopic branch of the Nile was separated from the Bolbitic-Rosetta branch, 33 km inland from the mouth of the river, and diverted to the west, traveling towards Alexandria. Again, 10 km from the coast, it is divided into two branches, one flowing towards Alexandria, and the other, diverted to the east, to the area of Canopos, leading eventually to the Abou Kir Gulf (see Chapter 1.2, geological characteristics). As the Canopic branch evolved, its riverbed shifted west, then east; finally its flow diminished and the water was much reduced at the end of the 1st millennia AD. The 87
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Rosetta branch became the major distributary at the beginning of the 2nd millennium AD, developing about 25 km east of the Abou Kir projection, at its present location, and discharging sediment at the eastern margin of Abou Kir (Stanley et al. 2004a). At the western part of Abou Kir, along the mouths of the Canopic branch, when the delta shoreline was 5 km north of its present coast, the cities of East Canopus and Herakleion were two low-lying coastal sites until the 8th century; today their remains lie at 5–7 m below sea level (Stanley et al. 2004b; Goddio 2007). Stanley et al. (2004b) attributed the 4–5 m of observed submergence to relative sea level rise (eustatic rise and land subsidence due to sediment compaction and possibly due to the loading and sediment remobilization of the water-saturated substrate of the extensive building activities of the cities), leading to a subsidence of approximately 3mm/year for 1300 years; and, additionally, 3–4 m of subsidence due to episodic failures during floods, earthquakes and, probably, tsunamis. According to Chalary (2007), the cities of Herakleion and Canopus were submerged due to a prolonged period of high flooding from the Nile, which caused liquification of the substrate of the constructions. After the construction of the Aswan Dam, a loss of sediment was provoked, which, in combination with the eustatic sea level rise and the isostatic subsidence of the land, led to a greater relative sea level rise in the Abou Kir Gulf (Chalary 2007). Masts of ships from Napoleon’s fleet sunk during the Battle of Abou Kir (1–3 August 1798) could be seen in the bay until 60 years ago: they have now disappeared (Zerefos et al. 2008). A fish tank has also been noted and investigated in the area of Abou Kir. The site is 2 km west of the edge of the Abou Kir promontory, on a rather undeveloped beach (see Chapter 20). 9.12 Nelson’s Island (Abou Kir Island) Nelson’s Island, 350 m long and located 4 km offshore of Abou Kir, was connected via a narrow strip with the mainland during Hellenistic and, probably, Pharaonic times. The promontory of the island is likely to have had large public structures that overlooked the cities of Herakleion and East Canopus. In the 3rd century AD the site was suddenly abandoned, probably for geological reasons and/or the persecution of other faiths by the Christians. In the 5th century AD the island was turned into a quarry and the site was finally abandoned in the 8th century, together with Herakleion and East Canopus. 88
10. Fish tanks According to Greek and Latin authors, the development of pisciculture is placed before Roman times (Higginbotham 1997). According to Plato, pisciculture was practiced along the Nile and the Egyptians had built large enclosures that were incorporated into religious complexes and royal palaces. Several Egyptian sources dating between the 3rd century BC to the 7th century AD refer to the wide use of fresh-water and sea fish for food and the existence not only of fishermen, fish markets, fishing rights, fishing methods and fish salting, but also of fishing taxes in ancient Egypt (Besta 1921). The Nile Delta coasts are abundant in fish as a result of the nutrient-rich Nile waters flowing out into the Mediterranean. Sea level indicators may depict either rapid or slow sea level changes, and in areas such as the Mediterranean, sea level indicators may represent a combination of both eustatic and tectonic causes. During the Roman era many fish tanks were built along the Mediterranean (Plinius, Naturalis Historia, IX; Columella, De Re Rustica, XVII; Varro, De Re Rustica, III) and particular features of these tanks were tidecontrolled (e.g. crepidines, moles, sluice gates). Geoarchaeological analysis in coastal areas provides good proxies for past sea levels, making it possible to correlate some coastal structures (fish tanks, docks) to sea level (Schmiedt 1972; Pirazzoli 1976; Leoni and Dai Pra 1997). It is recognized that fish tanks may be considered as palaeo-sea level markers that allow accurate evaluation of relative sea level variations over the last two millennia (Schmiedt 1972; Lambeck et al. 2004). The measurements of the depth of features (foot walks (crepidine), sluice gates, top of channels, moles, etc.) may provide information of relative sea levels at the time of construction. It is possible to use these values as markers of past sea levels, but only after corrections for tide, atmospheric pressure and waves at the time of surveys are applied, considering general meteorological conditions and after evaluation of error bars for elevations. Moreover, the understanding of the hydraulic functions of these features is required for successful interpretation of the main sea level indicators. 89
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Estimates of the upper limits are based on the measurements, relative to mean sea level, of the present height of the top of some elements (surrounding walls, partition walls between basins, shore benches in which channels for water supply have been cut, and grooves for the sliding of water gates and fishing nets) and on assumptions related to the position of these elements during high tide. Estimates of the lower limits are mainly based on the fact that, with less than 5 or 10 cm of water at high tide over the bottom of the channels or at basin entrances, water inflow would not have been possible (Schmiedt 1972; Lambeck et al. 2004, Evelpidou et al. 2012a). 10.1 Fish tanks in Alexandria The study area is located on the coastal zone of Alexandria from the Silsilah to Abou Kir promontories (Figure 34). Alexandria was built on a long coast-parallel ridge of the Pleistocene era that extends from the southwestern part of Alexandria to Canopus, the modern town of Abou Kir. The ridge, called Abu Sir, reaches a height of 35 m at its western part and 6 m in Abou Kir; it was formed by poorly to moderately cemented
Figure 34: The area under study and evidence of possible fish tanks in the littoral region of the east end of the Maamourah Gulf to Abou Kir promontory.
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sandy carbonate, known as kurkar formation (Butzer 1960; Stanley and Hamza 1992; Hassouba 1995). The astronomical tides of Alexandria, ± 20 cm, are negligible in comparison to the 1 m height due to meteorological factors (El Geziry 2013). The mean sea level between the daily readings of high and low water level during the period 1898–1906 has been set as the mean sea level (m.s.l.) datum at the port of Alexandria, and was found 33.8 cm above the zero of the installed tide gauge (Dawod 2001). The m.s.l. for the period 1944–1989 was calculated at 40.0 cm (Frihy 1992), for the period 1956–1966 at 44.1 cm (Sharaf El-Din 1975), for the period 1974–2006 at 47.9 cm (Said et al. 2012), and for the period 1996–2005 at 50.67 cm, above the zero of the installed tide gauge (El Geziry and Radwan 2012). A detailed survey of the Alexandria coastline took place during the Hellenic Institute of Ancient and Mediaeval Alexandrian Studies (HIAMAS) missions of 2014–2016. The region was systematically surveyed, and the submarine areas were studied by snorkeling and, occasionally, by scuba diving. During fieldwork, fish tanks were mapped in detail and their most significant morphological characteristics were measured. Several measurements were performed on each location and the accuracy was improved by multiple measurements. Geographic locations of measurements are reported as Long/Lat coordinates with an average accuracy of ±5 cm using GPS. The observed features were photographed and measured in relation to sea level at the time of observation. Precise depth measurements were obtained using a hand-held sonar and a 3-m metal bar with centimeter division and built-in spirit level. Multiple measurements were performed, and the average is provided as the depth value. The methodology applied includes correction of measurements for real tide and atmospheric pressure values at the exact time of the measurements and also evaluation of height and functional depth in relation to the average sea level, which differs depending on the typology of evidence, its use, and local tide amplitudes. From the diurnal trend of sea level (graphs from the Sea Level Monitoring Facility, Intergovernmental Oceanic Commission (IOC)) the difference of sea level at the time of measurements in relation to the maximum sea level of that particular day have been calculated and the measurement value was correspondingly corrected. For atmospheric pressure corrections, for example, the difference of the atmospheric pressure (P) in October 2014 (1016.0 hPa) from the long term of October P (1015.3 hPa) was estimated. Based on the table Correzioni da Applicare alle Alteze di Marea per la Variazione della Pressione Atmosferica of the ‘Tavole di Marea’ (1982), Instituto Idrografico della Marina (Italy), a change of sea level by 1 cm for a change of pressure by 1 hPa (1 cm/ hPa) has been taken into consideration, while Saad et al. (2011) suggest 91
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1.4 cm/hPa. Furthermore, if it is considered that at 2000 BP the seasonal change of sea level was similar to the contemporary, the maximum sea level occurs in August, and, therefore, based on the measurement of 14 October 2014, the maximum sea level in August 2014 can be estimated, i.e. how much higher the sea level was in August 2014 in relation to October 2014. The long-term sea level change (mean 1956–1966, 1995–1999) has been provided by Sharaf el Din (1975) and Dawod (2001). This is 50 cm in October and 56 cm in August, therefore sea level in October is lower by 6 cm on average and the measurements should be increased by 6 cm. The same procedure was followed for October 2016 (P 2015.7 hPa) and for June 2014 (P 2012.3 hPa), while the long-term mean pressure for June is 1011.6 hPa. Sea level variations driven by glacioisostatic adjustment for the study area have been modeled using an improved version of the Sea Level Equation solver SELEN (see Spada and Stocchi 2007), in which the horizontal migration of shorelines, the timeevolution of the ocean function and the rotational feedback on sea level change have been considered. The first of the two GIA models employed is the last of the suite of ICE-X models produced by Peltier and collaborators (i.e. ICE-6G (VM5a) of Peltier et al. 2015) while the second, labelled by ANU, is the model progressively developed by Lambeck and co-workers (see Nakada and Lambeck 1987; Lambeck et al. 2003, and further refinements). 10.2 Fish tank findings Several fish tank installations have been noted on the coastal zone of Alexandria (Table 1), as shown in Figure 34. The fish tanks of Miami Island, Montazah and Abou Kir have been studied in detail. Fish tanks are also evident in satellite images in the littoral area c. 3 km from the east end of the Maamourah Gulf towards the Abou Kir promontory (Figure 34). At least four fish tank structures were identified (Figure 34). Regrettably these structures are enclosed in military installations and even superficial
Site name Miami Island Montazah Abou Kir Sporting Beach FT1 FT2 FT3 FT4
Table 1: Fish tanks identified and discussed in the text, with their geographical coordinates
Longitude 29° 59' 24" E 30° 01'13.63" 30° 03'41.06" E 29° 56' E 30° 02'40.74" E 30° 02'51.01" E 30°03'00.48" E 30° 03'11.64"’ E
Latitude 31° 16' 20" N 31° 17'40.25" N 310 19'27.05" N 31° 13' N 31° 18'47.39" N 31° 19'02.07" N 31° 19'08.05" N 31° 19'11.11" N 92
Comment Studied Studied Studied Evidenced (submerged) Evidenced in satellite images Evidenced in satellite images Evidenced in satellite images Evidenced in satellite images
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observation cannot be considered. One further installation is discussed as a possible fish tank, at Sporting Beach. From the three studied in detail (Miami, Montazah and Abou Kir), the Montazah tank is very well preserved. A further fish tank is possibly located at the western part of Miami Island, apart from the one in the centre of the island, which is discussed in this chapter; however it was not visible due to the rubble surrounding it. The approximately 2–3 m underwater formation at Sporting Beach (HIAMAS Report No 9, 2002), attributed probably to a Necropolis and thereafter as a quarry, could have also been used at some time as a fish tank, or at least a part of it, as divers recognized rectangular-shaped divisions of appropriate dimensions and some channelization cut into the rock, as well as some quarrying basins (HIAMAS Report No 27, 2014), but this should be further studied in the future. 10.2.1 Montazah fish tanks The site is in the bay of Maamourah (30°01'13.63" E, 31°17'40.25" N), an open, wide bay (c. 3 km) dotted with several islets, c. 14 km east of Alexandria’s East Harbour. Maamourah lies between the small bay of Montazah (c. 400 m wide) to the west and the promontory of Abou Kir to the east, after which the vast Gulf of Abou Kir (c. 33 km wide) is extended (Figure 34). The bays of Maamourah and Montazah were mainly one feature, embracing an oblong island (perpendicular to the coast, c. 420 x 100 m) near its western end and called ‘Geziret Halawa’. King Farouk (reigned 1936–1952) connected this island to the shore with a bridge and called it the ‘Island of Dreams’ (Geziret el-Ahlam) or ‘Tea Island’. Later, the sedimentation settled around the bridge’s foundations and a spit was formed, creating two bays. Breccia (1926) reports that ancient remains and a Roman cemetery were discovered when the Haramlek Palace was constructed at Maamurah, and mentions that the whole Maamourah promontory was possibly a summer resort for the Romans. The Montazah fish tank complex consists of several large tanks cut into the rock crowning the northern edge of the island, where there are many cuttings and remains of constructions. At this fish tank, the most important measurements performed (Table 2) refer to channels, submerged arches, crepidines and sliding grooves. The Montazah fish tank is a large construction, covering a total area of approximately 4335 m2 and very well preserved. The wonder of this fish tank at Montazah is not only its size but also its architecture. It is composed of four main parts, each divided into many smaller tanks (Figures 34, 35). They all communicate in various ways through channels, or arches. The outer walls were cut so that they stand higher than the inner ones to protect the tank from storms (Figure 36). The height of the outer walls is c. 8 m, ensuring relatively calm water inside the tank, no matter the sea conditions outside. It seems likely, therefore, 93
Figure 35: The Montazah fish tank consists of four main parts, each divided into many smaller tanks linked with each other through channels or arches.
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Figure 36: The cut, outer walls of the Montazah fish tank stand higher than the inner ones to protect the tank from the storms.
that the Montazah fish tank was not affected by frequent strong waves and surge effects. There are nine cuts in the rock, functioning as external channels and allowing fresh water to enter the main channel of the tank. This main channel surrounds the tank, with a length of some 67 m. The internal walls of this main channel are neater than the external ones and were probably used to walk around the tank and, possibly, for fishing. Generally, as in many cases, there were terraces used as walkways and platforms from where the complex and panorama could be enjoyed. For example, at Torre Astura (Italy), a long bridge provided access to the insular fish tank and allowed visitors to experience the sights and sounds of the sea from sheltered pavilions from within the tank itself. These broad platforms could have offered better views, while providing shade for the fish held in the enclosure (Higginbotham 1997). These features also emulate the larger and more prestigious coastal fish tanks, where many were built with dining facilities (Ricotti 1987). The passages were also modified to facilitate trapping fish and controlling their movement in and out. The advantages of fishing within a controlled environment are obvious: protection from the dangers of the sea and a ready store of fresh food, easy to catch (Plautus, Rudens). 95
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Figure 37: Short channels connect the tanks and distribute the water, ensuring adequate circulation within the fish tank.
The tanks are connected through short channels (Figure 37). Within the standard architecture of Roman tanks, the existence of several different storage compartments is common. Smaller channels would distribute the water and insure adequate circulation inside the fish tank. Columella suggests that channels were positioned on every side of the fish tank, low down on the wall of the enclosure, so that the water forced through these openings would originate from the cooler and more nutrient depths of the sea. Especially in channels C and D, sliding grooves cut into the stones (Cs and Ds respectively) were found to be used as sluice gates (Figure 38a, b). In the western part of the fish tank, which is the largest one with fewer smaller tanks or preserved partitions (Figure 39), a continuous, submerged tidal notch was found 24 cm below mean sea level (Figure 40). According to Evelpidou et al. (2012b) it is considered as a relatively modern feature, since the possibilities of intertidal bioerosion are exceeded by the rate of global sea level rise in the 19th and 20th centuries and resulting in the absence of the development of a modern notch. 96
10. Fish tanks Figure 38: A) Channel C in the Montazah fish tank; B) its sliding grooves (Cs) cut into the stones used for the fitting of sluice gates.
Figure 39: The western part of the Montazah fish tank is the largest, but with fewer smaller tanks (or possibly the partitions have not survived).
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Figure 40: Submerged tidal notch at -24 cm found at the western part of the Montazah fish tank.
The eastern part of the fish tank is the most complex with many divisions within the main tank; only in this part of the fish tank was a channel for fresh water input from the inland into the fish tank found (Figure 41). Sedimentation has clearly occurred in this western section of the structure. Sluice grooves were found along the fresh water channel, obviously to regulate the fresh water supply. Several Latin authors mention the usefulness of mixing fresh water with sea water – to attract fish into the tank or decrease salinity during summer. This makes sense, especially in Egypt, and the eastern part of the structure appears to be shallower than the rest – some channels then were probably used for bringing in fresh water (see the Grottacce and Saracca fish tanks in Italy) (Chiappella 1965). 10.2.2 Abou Kir fish tank The site is situated 2 km west of the edge of the Abou Kir promontory (30°03'41.06" E, 31°19'27.05" N), in a rather unexploited area of the beach. The Abou Kir fish tank is situated off the homonymous beach, east of Alexandria. This fish tank is the easternmost in a series of sites, found at the east end of Maamourah Bay, towards the 98
Figure 41: Τhe eastern part of the Montazah fish tank is the most complex, with many divisions within the main tank. In this part was found a channel for fresh water input from inland to the tank.
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Abou Kir promontory. They can be seen, unfortunately, only in satellite images, as they are enclosed in military installations (Figure 34). The Abou Kir fish tank is not well preserved and the inner basin has been silted; it is a gamma-shaped, undistinguished construction (Figure 42). The simple form of this tank may correspond to the rustic nature of the area. The constructor utilized the
Figure 42: The Abou Kir fish tank, a simple, gamma-shaped construction.
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10. Fish tanks
Figure 43: The outer defensive wall of the Abou Kir fish tank.
coastal rock formations that functioned as outer barriers to protect the fish (Figure 43). In this rock-cut complex there are numerous small, rectangular tanks (4.10 x 8.50 m). In an analogous manner to harbour design, moles are laid out to protect the area where the fish tank was constructed. Channels ensured the exchange of the tanks’ water with the open sea. In this tank only the lower crepidine was found, at -93 cm from MSL (Figure 44). Breccia (1926) in his publication on the ruins and monuments of Canopo, the ancient Kάνωπος, wrote that Abοu Κir area was a region for trade, but also a recreational area for wealthy citizens. He goes on to describe fish tanks and included a map drawn by Bartocci (1925) (Figure 45). Breccia presents sketches and photographs of some of them along that coast. One of these can be identified on Google Earth – site 30002'51.01'' E, 31019'02.07'' N (Figure 46a). Breccia describes the striking similarities of that particular fish tank with the one at Castello Del Sangallo in Italy, described by Jacono (1924) (Figure 46b). Figure 46c shows an image of this fish tank in 1926. 101
Geophysical Phenomena and the Alexandrian Littoral
Figure 44: The lower crepidine in the Abou Kir fish tank, found at -93 cm.
Figure 45: The Abou Kir area, according to Breccia (1926), included several fish tanks (based on Bartocci 1925).
102
10. Fish tanks
Figure 46: (A) FT2 fish tank (see Figure 30) as seen on Google Earth in a satellite image of 2004, which (B) is described by Jacono (1924) and compared with Castello Del Sangallo in Italy.
103
Geophysical Phenomena and the Alexandrian Littoral
Figure 46C: A photograph of the fish tank at Abou Kir as described by Breccia (1926).
10.2.3 Miami Island fish tank The island (Gezirah) of Gabr el Khour, now called Miami Island, lies at 29° 59' 24" E, 31° 16' 20" N, about 150 m off Sidi-Bishr beach and approximately 10 km east-northeast of the Silsilah promontory of Alexandria. It is an oblong island of c. 220 m in length to 60 m wide, with its long axis running almost parallel to the coast and its highest point, almost 4 m.a.s.l., at the central area. The surface is almost entirely covered by pits, ridges and sharp razor points that typify karrenfeld erosion of eogenetic limestones. The island apparently had several uses during various periods, and it is covered with deep man-made, rock-carved pits, burial remains, rooms, corridors, quarrying marks and other unidentified remains. There are many indications that the island was part of the large necropolis of Sidi-Bishr during the first centuries of Alexandria. The manmade superficial carvings in the underwater littoral (HIAMAS 2009, Rep. 20) indicate submergence, which certainly had occurred before the fish tank constructions. The rock carvings in the central region of the island attract attention. They are to be found southeast of the central region over an area of c. 20 x 20 m almost at the level of the sea (Figures 47 and 48). At this southeast central part of the island a fish tank construction is visible. In this case, Miami island itself acts as protection from storms of this installation. Similar to the other investigated fish tanks along the wider Alexandria 104
10. Fish tanks
Figure 47: The Miami Island fish tank.
coast, the Miami tank is rock-cut. Although it is not a large construction (~2287 m2), it is complex and sophisticated. The construction includes, among its other features, a narrow tank dug into the rock, cave-like, providing some shade for the fish during the day (Figure 48). It also includes channels enabling the renewal of the tank’s water from the open sea (Figure 48). Two crepidines have been noted (Figure 49); the lower one should have always been submerged, not much higher than the bottom of the basin, and the upper one, which was used as a walkway, e.g. during maintenance, should have always been dry. There is a large, main channel cut around Miami island, with its outer wall some 5 m above m.s.l. (Figure 50). The construction is very similar to the Montazah fish tank, thus it was possibly designed by the same contractor. The eastern part of this main channel was used to refresh the tank’s water. The main channel runs for ~47 m along the island (perimetrically), however, at the western tip the end is not clear. Although at the western end of the main channel there seems to be no evidence of a tank, it may well be buried under the neighbouring rubble. 105
Geophysical Phenomena and the Alexandrian Littoral
Figure 48: The Miami Island fish tank, a complex and sophisticated construction, is carved in the southeastern region of the homonymous island. To the left is a narrow tank dug into the rock (A), which we assume was constructed to provide some shade for the fish during the day. Channels may also be noticed for the renewal of the tank’s water supply from the open sea (B).
Figure 49: The crepidine in the Miami Island fish tank.
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10. Fish tanks
Figure 50: The main channel cut around Miami Ιsland.
Table 2 indicates all the measurements taken at the fish tanks in relation to the present m.s.l. The morphological characteristics of the Miami island fish tank corresponding to the Roman m.s.l. are the crepidines and the channels. Table 2: Measurements from on the fish tanks studied and architectural characteristics Site
Corrected depth measurements (cm) related to mean sea level (+/- 5 cm)
Type
Schemas
Montazah
A
-38
channel
B
-120
channel
107
Geophysical Phenomena and the Alexandrian Littoral
Site
Corrected depth measurements (cm) related to mean sea level (+/- 5 cm)
Type
C
-116
channel
Schemas
Cs
+30
sliding grooves
D
-111
channel
Ds
+32
sliding grooves
E
-84
channel
F
-111
channel
108
10. Fish tanks
Site
Corrected depth measurements (cm) related to mean sea level (+/- 5 cm)
Type
G
-79
channel
Schemas
H
-3
channel
I
-139
channel
N
-70
submerged arch
O
-99
rank
P
-58
crepidinae
R
-34
crepidinae
S
-50
crepidinae
109
Geophysical Phenomena and the Alexandrian Littoral
Site
Corrected depth measurements (cm) related to mean sea level (+/- 5 cm)
Type
T
-67
crepidinae
U
+17
sliding grooves
Abou Kir A
+42/+2
wall
B
+6
wall
C
+15
wall
D
-60
tank
G
-72
tank
H
-93
crepidinae
I
-87
tank
J
-88
tank
110
Schemas
10. Fish tanks
Site
Corrected depth measurements (cm) related to mean sea level (+/- 5 cm)
Type
K
-122
channel
Miami A
-20
crepidinae
Α1
-15.5/-30
crepidinae
B
-114/-130/-150
crepidinae
Β1
-22
crepidinae
Β2
-24/ -38.5
crepidinae
C
-36
crepidinae
D
-51/-65
crepidinae
E
-108
channel
111
Schemas
Geophysical Phenomena and the Alexandrian Littoral Corrected depth measurements (cm) related to mean sea level (+/- 5 cm)
Type
Ε1
-119
channel
Ε2
-100
channel
F
-49
crepidinae
Site
Schemas
10.3 Main sea level indicators The positions where measurements were taken from the tanks are depicted in Figures 35, 42 and 47, while measurement characteristics appear in Table 2. To reconstruct the former m.s.l. it is essential to interpret all fieldwork measurements and select the best sea level indicators for each tank. To do so the following criteria were used. 10.3.1 Protective moles For harbour designs, moles were built to protect an area within which a fish tank could be constructed. The perimeter moles had the function of protecting the ponds from the violence of the sea and also created calmer conditions for breeding fish (Martial, Epigrammaton libri X) (Figures 36, 50). Moles may provide information for relative sea levels at the time of construction. According to Columella, one of the main characteristics for fish tanks is an outer protection breakwater (mole), constructed all around the basins and exceeding basin levels (Columella, R.R. XVII.10: ‘Mox praeiaciuntur in gyrum moles, ita ut complectantur sinu suo et tamen excedant stagni modum’ (‘In addition moles are constructed all around in order to surround the basins and exceed their level’). On 23 October 2016 at Montazah, and 18 October 2016 on Miami Island, the height of the waves was c. 5 m. The design of the fish tanks make it clear that the protective moles were essential for these constructions to survive and function properly. The Abou Kir tank provides an example of a simply constructed mole, and it seems clear that the tank was not as well protected, i.e. with a high-walled channel or an island, as the tanks of Montazah and Miami Island respectively. It may be assumed that the Abou Kir tank has been subjected to erosion, which has significantly reduced the outer 112
10. Fish tanks
breaker mole. On the other hand, the outer moles of the Montazah and Miami Island tanks have limited the amount of erosion to them. At Abou Kir, the levels of both the outer mole and the crepidines have been lowered by an unknown amount by erosion. The best-preserved top to the mole at Abou Kir is at site Α, measured at +42 cm, but this has been partly eroded by wave activity and was always emerged. 10.3.2 Upper walkway (upper crepidine) Evelpidou et al. (2012a) propose that the former tank m.s.l should be 35 cm below the top of the best-preserved upper crepidine. Such an estimate, however, has the drawback of lowering the ancient m.s.l. when the upper crepidine is eroded. Since the Montazah tank was protected from erosion by the outer mole, it may be assumed that the bestpreserved upper crepidine at Montazah well corresponds to its original position. Based on the present measurements, it may be proposed that the former m.s.l. was slightly lower than the top of the best-preserved upper crepidine at site (R) of the Montazah tank, which was found at -34 cm (Table 2). Based on this, the geomorphological characteristic m.s.l. for the tank over the functioning period should be c. 69 cm below the present m.s.l. 10.3.3 Lower crepidines In some cases there is evidence for lower walkways, used for maintenance, oyster culture, etc. Often this feature is to be found very close to the bottom of the tank, and thus impossible to have remained above water, as in this case the depth of water in the basin would have been insufficient for fish to survive. It is obvious that this morphological characteristic may not be used as an indicator of sea level, but indicates only a limit. A well-preserved lower crepidine can be seen in the Miami tank (Figure 49) and, in fact, site (B) has three, one below the other (see sketch in Table 2). Their depths (-114, -130, -150 cm) and the vertical distance between the top of the lowest one and the bottom of the tank (see figure 49) verifies that they should be always be assumed as submerged. 10.3.4 Closing gates (cataractae) Morhange et al. (2013) report that mid-tidal closing gates (cataractae) in situ, which are precise indicators of relative sea level change, are exceptionally rare due to their original location in the wave-breaking zone. The closing gates could be solid, to stop incoming water, or a net, or sluice, with small holes to allow water to enter, while preventing larger fish from escaping. Cataractae were located at the upper part of the fish tank, at the levels of the tidal range. Sluice gates along the channels, or between the basins, operated along sliding grooves cut into stones; their marks may be particularly useful, if well interpreted, for estimating former sea levels. 113
Geophysical Phenomena and the Alexandrian Littoral
Prints of sluice gates have been noted at several sites within the Montazah tank complex (see Figure 38a, b), at +30 cm, coinciding with the top of the upper walkway. The upper limit of the sluice gates should be always seen as emerged, indicating the upper sea level limits. 10.3.5 Channels Channels were used to connect the tank with the open sea to ensure water renewal. Channel directions range according to the individual morphological and hydrodynamic coastal characteristics of the area, trying to take advantage of wave power so as to let fresh water pass into a fishpond. Columella has suggested that channels were positioned on every side of the fish tank and low down on the wall of the enclosure, so that water forced through these openings would originate from the cooler depths of the sea. Some of the channels are vertically separated by a bar. Smaller channels would distribute the water and further insure adequate circulation between the smaller basins inside the tank (Figure 37). Some channels were used for bringing fresh water from inland to the tank. These channels were used by certain species of fish during their seasonal migrations and were thus perfect spots to catch fish. Such an example can be seen in the Montazah tank (see Chapter 10.2.1, Fish tanks). The outer part of the tank, towards the open sea, could be blocked by gates to stop fish leaving for the open sea. Sluice gates were used for this, operating along sliding grooves cut into stones. Channels open to the sea had to supply water, at least during the high tide cycle (Pirazzoli 1988). According to Schmiedt (1972), the tops of the channels had to remain above water during even the highest tides. In fact, he assumes that the tops of the channels needed to have been at least 40 cm above the former m.s.l. to allow workers at the tanks to reach the entrance of the outer channels. Estimates of the lower limits of past sea levels are based on the premise that at least 10 cm of high-tide water must have passed over the bottom of the supply channels at a basin entrance to ensure viable conditions were maintained inside the tank (Caputo and Pieri 1976; Flemming and Webb 1986; Leoni and Dai Pra 1997; Evelpidou et al. 2012a; Morhange et al. 2013). The best-preserved channel sites in terms of measurements, being sure that sedimentation at the bottom does not affect readings, are: I (-139 cm) at Montazah; K (-122 cm) at Abou Kir; and E1 (-119 cm) at Miami Beach (see Figures 35, 42 and 47 respectively). 10.4 Relative sea level changes and Alexandria’s fish tanks The fish tank installations along the coastal zone of Alexandria suggest that during Roman times Alexandria had a commercial role in the fresh fish export. Catching fish in a tank is not difficult and, once caught, they could be transported along short 114
10. Fish tanks
distances in nets, trailing in the water, or in a boat (Plinius, Naturalis Historia IX). For longer distances, and to insure the health of the fish, boats equipped with tanks could have been used (Macrobius, Saturnalia III). Athenaeus of Naukratis (Deipnosophistae, V, 208) describes a ship called the Syracousia, built by Archimedes at the behest of the tyrant Hiero II of Syracuse (3rd century BC); this vessel had a tank built into her bow, constructed of lead and wood. This tank was filled with sea water and fish were kept in there, alive, during the trip. During the construction of the airport at Fiumicino in 1958/9, a boat with such a tank for live fish (navis vivaria) was unearthed near what was the entrance to the Claudian harbour (Scrinari Santa Maria 1979). A lead pipe that ends in a hole through the hull discovered in a wrecked ship of the 2nd century AD off the coast of Grado in NE Italy, presumed to be part of a pump (which was not discovered) used to replace the water in the stern, keeping the fish alive during transport to the fish markets (Beltrame et al. 2011). Vessels such as these could land along the protective moles of most marine fish tanks and simply transfer their catches to ponds. Piers and moles would have facilitated the transfer of fish into their enclosures, as well as their onward shipment to market. Such boats, therefore, could well have been used to transfer fish from Alexandria to Europe, keeping them fresh. According to Breccia (1926), ‘Né forse si fa ipotesi troppo ardita ammettendo che Alessandria anche in questa come in altre manifestazioni della vita e dell ‘arte, specialmente della vita lussuosa, abbia offerto a Roma il modello e l’esempio.’ Thus, are we looking here at another instance where Alexandria, in this as in other manifestations of life and arts, especially with regard to luxurious living, has provided a model for Rome? Based on the hydraulic characteristics of the tanks studied, and having used the most appropriate and well-preserved features, we have tried to estimate the relative sea level changes since the Roman era, assuming that tide, wind and air pressure then were similar to the present. It should be noted that while a depth of only 88 cm below mean sea level was measured for the Abοu Κir tank, Columella records that for this type of tank the depth should be around 9 feet (2.74 m), suggesting that sedimentation in the tanks is of the order of 2 m. Similar differences have been noted for Sarinola fish tank (Evelpidou et al. 2012a). On the other hand, at Montazah the depth of the fish tank was measured c. 98 cm and at Miami c. 1.70 m, seeming to verify that lower levels of sedimentation at these two constructions.
115
Geophysical Phenomena and the Alexandrian Littoral
According to the present measurements and interpretations of the functionality of the tanks during their operational period, and taking mainly into account the bestpreserved elements, i.e. upper crepidine at site R (-34 cm) at Montazah, it seems that sea level has risen by some 70 cm over the last 2000 years in the relatively stable part of Alexandria. At Miami, measurements at sites A1 (-30 cm), B2 (-38.5 cm) and C (-36 cm) all lead to the same conclusion. The findings of the present study agree quantitatively with data from other relatively stable areas around the Mediterranean: i.e. at ancient harbours and coastal installations in the western Mediterranean (Blackman 1973; Morhange et al. 2001). In Fréjus, France, Morhange et al. (2013) report a RSL rise of 40 ± 10 cm since Roman times, consistent with a recently published Roman sea level of -32 to -58 ± 5 cm for the northwestern Mediterranean for the same period. Along the Tyrrhenian coast of Italy, Evelpidou et al. (2012a) report that local sea level during the Roman period did not exceed 58±5 cm below present sea level. In Israel (Sivan et al. 2001; 2004; Galili et al. 2005; Anzidei et al. 2011), relative sea level has been fairly stable since c. 4000 BP, when it reached its present level, with possible fluctuations not exceeding 0.5 m. Goiran et al. (2009) obtained a date of 2115 ± 3014 cal BP (230–450 cal AD) for a mole within the ancient harbour of Portus in the Latium region, on the right bank of the mouth of the Tiber, indicating a former sea level of 80 ± 10 cm below modern MSL. Here a slight offset due to deltaic subsidence needs to be considered. Studies in relatively tectonically stable areas have shown that they are characterized by negligible isostatic effects (e.g. Sivan et al. 2001; 2004; Toker et al. 2012), indicating that sea level was close to present levels by 4000–3600 BP (Galili and Sharvit 1998; Galili et al. 2005; Porat et al. 2008). Different studies along the Mediterranean coasts (e.g. Sivan et al. 2004; Toker et al. 2012; Vacchi et al. 2016; 2017) have shown that relative sea level fluctuated either below or slightly above the present height since 4000 BP.
116
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Alexandria is located on the Mediterranean coast of Egypt, bordered by Egypt’s Western Desert and the fertile Nile Delta. For many centuries, Alexandria was the major port city in the Eastern Mediterranean and it has been repeatedly struck by natural disasters, such as earthquakes, tsunamis and land subsidence, in its ~2400-year history. This book focusses on the geomorphological and archaeological evidence on the coastal zone of Alexandria, attempting to provide a comprehensive review of its evolution, taking into consideration long-term and short-term factors. Geophysical Phenomena and the Alexandrian Littoral provides an extensive background on the geomorphology and recent geoarchaeological history of Alexandria, discussing historical maps and natural disasters. In the coastal area of Alexandria there is numerous archaeological evidence, such as burial sites, quarry activities and ancient building remnants, as well as geomorphological features, all revealing a complex evolution of the coastal zone. New evidence, such as fish tanks and ship wrecks in order to discuss the Late Holocene evolution of the coastal zone. Detailed illustrations and maps accompany the book chapters providing the reader the opportunity to gain an extensive view of Alexandria’s features. Niki Evelpidou is a Professor of Geomorphology and Geoinformatics at the National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, and Faculty Affiliate of the Department of Geology and Environmental Geosciences of the College of Charleston, USA. Prof. Evelpidou is actively involved in the research fields of geomorphology, coastal geomorphology, sea level changes, palaeogeography, geology, spatial technologies, study and modelling of natural hazards, while emphasizing on the use of new technologies and innovation. Christos Repapis was Director of the Research Centre of Atmospheric Physics and Climatology of the Academy of Athens (1985-2005) and has remained as Research Associate of the Centre since his retirement. Christos Zerefos heads the Research Centre for Atmospheric Physics and Climatology, Academy of Athens and is president-elect of the General Assembly of the Hellenic Foundation for Research and Innovation. Other roles academic posts include Professor of Atmospheric and Environmental Physics (Universities of Athens and Thessaloniki), Visiting Professor (Universities of Minnesota and Boston) and Samarbeidspartnere (University of Oslo). Harry Tzalas has conducted a range of innovative experimental archaeological studies relating to ancient sea vessels. In 1997 he formed the Hellenic Institute of Ancient and Mediaeval Alexandrian Studies and obtained a concession from the Egyptian Authorities for an underwater survey of 14 kilometers of the eastern littoral of Alexandria; 28 campaigns were successfully conducted. Costas Synolakis is Professor of Civil Engineering at the University of Southern California and a a member of the Academy of Athens holding the Chair of Earth Sciences. His research studies the impact of natural hazards, and particularly tsunamis and extreme flooding events on beaches. He has participated or led 30 scientific expeditions in 21 countries, practically in all of the world’s oceans and seas.
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