Black Sea deluge hypothesis

The Black Sea deluge is the most well known of three hypothetical flood scenarios proposed for the Late Quaternary history of the Black Sea. It is one of the two of these flood scenarios which propose a rapid, even catastrophic, rise in sea level of the Black Sea during the Late Quaternary.[1][2]

Map of the Black Sea

Black Sea deluge hypothesis
Black Sea today (light blue) and in 5,600 BC (dark blue) according to the hypothesis by Ryan and Pitman

In 1997, William Ryan, Walter Pitman and their colleagues first published the Black Sea deluge hypothesis. They proposed that a catastrophic inflow of Mediterranean seawater into the Black Sea freshwater lake occurred at 7,150 14C years BP (7550 calendar years BP).[3] Before that date, glacial meltwater had turned the Black and Caspian Seas into vast freshwater lakes draining into the Aegean Sea. As glaciers retreated, some of the rivers emptying into the Black Sea declined in volume and changed course to drain into the North Sea. The levels of the lakes dropped through evaporation, while changes in worldwide hydrology caused overall sea level to rise.

The rising Mediterranean finally spilled over a rocky sill at the Bosporus. The event flooded 100,000 km2 (39,000 sq mi) of land and significantly expanded the Black Sea shoreline to the north and west. According to these researchers, 50 km3 (10 cu mi) of water poured through each day, two hundred times the flow of Niagara Falls. The Bosporus valley roared and surged at full spate for at least three hundred days. They argued that the catastrophic inflow of seawater resulted from an abrupt sea-level jump that accompanied the Laurentide Ice Sheet collapse and the ensuing breach of a bedrock barrier in the Bosporus strait.

As proposed, the Early Holocene Black Sea flood scenario describes events that would have profoundly affected prehistoric settlement in eastern Europe and adjacent parts of Asia and possibly was the basis of oral history concerning Noah's flood.[3] Some archaeologists support this theory as an explanation for the lack of Neolithic sites in northern Turkey.[4][5][6] In 2003, Ryan and coauthors revised the dating of the early Holocene Noah's flood to 8,400 14C years BP (8800 calendar years BP).[7]

Popular discussion of this Early Holocene Black Sea flood scenario was headlined in The New York Times in December 1996[8] and later published as a book.[9]

Black Sea gradual inundation hypothesis

In addition to the early Holocene Noah’s Flood scenario proposed by William Ryan, Walter Pitman and their colleagues[3][7] and the Caspian Sea overflow scenario of Chepalyga,[10][11] the non-catastrophic progressive flood model (or gradual inflow model) has been proposed to explain the Late Quaternary sea level history of the Black Sea.[2][12] For the progressive flood model, it is argued that as early as 11,000 or 10,000 BP, the level of the Black Sea rose above the shallowest sill depth of about 30 m (98 ft) in the Bosporus Strait and spilled into the Marmara Sea. At least for the first 1,000 years, this connection was a one-way outflow of the Black Sea into a very shallow Marmara Sea. At about 8,000 BP, the level of the Marmara Sea rose high enough such that a two-way flow started. The evidence used to support this scenario includes the disparate ages of sapropel deposition in the eastern Mediterranean Sea and Black Sea; buried backstepping barrier islands observed on the Black Sea shelf; and a sub-aqueous delta composed of Black Sea sediments in the Marmara Sea near the Bosporus Strait.[13][14][15]

Late Pleistocene Great Flood hypothesis

In 2003 and 2007, a more ancient catastrophic flood scenario was proposed by Andrei L. Chepalyga for the Late Quaternary sea level rise of the Black Sea.[1][2][10] The hypothesis for a Late Pleistocene Great Flood argues that brackish Neoeuxinian Lake, which occupied the Black Sea basin, was rapidly inundated by glacial meltwater overflow from the Caspian Sea via the Manych-Kerch Spillway shortly after the Late Glacial Maximum, about 17,000–14,000 BP. These extensive meltwater flooding events linked several lacustrine and marine water bodies, starting with the southern edge of the Scandinavian and southward, through spillways to the Manych-Kerch and Bosphorus, ultimately forming what has been referred to as the Cascade of Eurasian Basins.[11] This event is argued to have caused a rapid, if not catastrophic rise in the level of the Black Sea. It might have imposed substantial stresses upon contemporary human populations and remained in cultural memory as the Great Flood. The authors also suggested that the event might have stimulated the beginning of shipping and horse domestication.[1][11]

Controversy
The Post-Glacial Sea Level.

The brief sensation caused by Ryan and Pitman has turned into an ongoing controversy. Critiques of the deluge hypothesis focus on the magnitude and pace of the water level rise. With enough moderation of these features, the catastrophe hypothesis is voided. However, a few key points should be noted:

  • Since the ending of the last glacial period the global sea level has risen some 120 m (390 ft). The process took approximately 10,000 years and abated about 7,600 years ago.
  • The flood hypothesis hinges on the geomorphology of the Bosphorus since the end of the glacial age.[16] The Black Sea area has been sealed off and reconnected numerous times during the last 500,000 years.[17]
  • Various methods have been used to study and date (e.g., sea floor drillings, radiocarbon dating, biological markers) the recent evolution of the Black Sea. The heterogeneous data do not fit into a neat frame, which precludes the confirmation for a sharply defined event.
  • The Black Sea flood hypothesis concerns an event supposed to have occurred during the last 10,000–12,000 years with the water level rising rapidly enough to cause easily noticeable effects.

Opponents of the deluge hypothesis point to clues that water has been flowing out of the Black Sea basin as late as 15,000 years ago.[18] The local level must have been higher than the current-then-global level which had already risen from the last glacial minimum. In order to produce a Black Sea flooding such as the one described by Ryan and Pitman a solid obstruction of the Turkish Straits should have occurred. It must have had a significant height to allow for a rise on the south side, while to the north the water level should have been dropping. A notable point here is that the low lands in the Black Sea's basin would have already been flooded.

In this alternative scenario, much depends on the evolution of the Bosphorus. According to a study from 2001, the modern sill is 32–34 m (105–112 ft) below sea level and consists of Quaternary sand over-lying Paleozoic bedrock in which three sills are found at 80–85 m (260–280 ft) below sea level. Sedimentation on these sills started before 10,000 years ago and continued until 5,300 years ago.[19]

A large part of the academic geological community also continues to reject the idea that there could have been enough sustained long-term pressure by water from the Aegean to dig through a supposed isthmus at the present Bosphorus or enough of a difference in water levels (if at all) between the two water basins.[20]

In 2007, a research anthology on the topic was published which makes much of the earlier Russian research available in English for the first time and combines it with more recent scientific findings.[21]

According to a 2009 study by Liviu Giosan, Florin Filip, and Stefan Constatinescu,[22] the level in the Black Sea before the marine reconnection was 30 m (100 ft) below present sea level, rather than the 80 m (260 ft), or lower, of the catastrophe theories. If the flood occurred at all, the sea level increase and the flooded area during the reconnection were significantly smaller than previously proposed. It also occurred earlier than initially surmised, c. 7400 BCE, rather than the originally proposed 5600 BCE. Since the depth of the Bosphorus, in its middle furrow, at present varies from 36 to 124 m (118 to 407 ft), with an average depth of 65 m (213 ft), a calculated Stone Age shoreline in the Black Sea lying 30 m (100 ft) lower than in the present day would imply that the contact with the Mediterranean might never have been broken during the Holocene, and hence there could have been no sudden waterfall-style transgression.[22] An August 2009 article, based on this same study, reported that the flooding could have been "not so big".[23]

A 2012 study based on process length variation of the dinoflagellate cyst Lingulodinium machaerophorum shows no evidence for catastrophic flooding.[24]

A 2015 study reviewed the evidence accumulated and acknowledged a "fast transgression" lasting between 10 and 200 years.[25].

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See also

References and sources
References
  1. Yanko-Hombach, V., Mudie, P., and Gilbert, A. S., 2011, Was the Black Sea catastrophically flooded during the post-glacial? Geological evidence and impacts, in Benjamin, J. et al. (eds.), Underwater Archaeology and the Submerged Prehistory of Europe: Oxbow Books, p. 245–262.
  2. Ferguson, S. (2012). Evaluation of Pleistocene to Holocene (MIS 5 to 1) climatic changes in southwestern Black Sea: a palynological study of DSDP Site 380. Master’s thesis, Department of Geology and Geophysics, Louisiana State University and Agricultural and Mechanical College, Baton Rouge, LA. 64 pp.
  3. Ryan, W. B. F.; Pitman, W. C.; Major, C. O.; Shimkus, K.; Moskalenko, V.; Jones, G. A.; Dimitrov, P.; Gorür, N.; Sakinç, M. (1997). "An abrupt drowning of the Black Sea shelf" (PDF). Marine Geology. 138 (1–2): 119–126. Bibcode:1997MGeol.138..119R. CiteSeerX 10.1.1.598.2866. doi:10.1016/s0025-3227(97)00007-8. Archived from the original (PDF) on 2016-03-04. Retrieved 2014-12-23.
  4. Ballard, R. D.; Coleman, D. F.; Rosenberg, G. D. (2000). "Further evidence of abrupt Holocene drowning of the Black Sea shelf". Marine Geology. 170 (3–4): 253–261. Bibcode:2000MGeol.170..253B. doi:10.1016/S0025-3227(00)00108-0.
  5. Hiebert, F. T. (2001). "Black Sea Coastal Cultures: Trade and Interaction". Expedition. 43 (1): 11–20.
  6. Özdoğan, M. (2011). "Submerged Sites and Drowned Topograhies along the Anatolian Coasts: An Overview". In Benjamin, J.; Bonsall, C.; Pickard, C.; Fischer, A. (eds.). Submerged Prehistory. Oxford: Oxbow. pp. 219–229.
  7. Ryan, W. B.; Major, C. O.; Lericolais, G.; Goldstein, S. L. (2003). "Catastrophic flooding of the Black Sea". Annual Review of Earth and Planetary Sciences. 31 (1): 525−554. Bibcode:2003AREPS..31..525R. doi:10.1146/annurev.earth.31.100901.141249.
  8. Wilford, John Noble (1996). "Geologists Link Black Sea Deluge To Farming's Rise". The New York Times. Retrieved 17 June 2013.
  9. Ryan, W.; Pitman, W. (1998). Noah's Flood: The New Scientific Discoveries about the Event that Changed History. New York: Touchstone. pp. 249. ISBN 978-0684810522.
  10. Chepalyga, A. L. (2003). "Late glacial great flood in the Black Sea and Caspian Sea". Geological Society of America, Abstracts with Programs. 35 (6): 460.
  11. Chepalyga, A. L. (2007). "The late glacial great flood in the Ponto-Caspian basin". In Yanko-Hombach, V.; Gilbert, A. S.; Panin, N.; Dolukhanov, P. M. (eds.). The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Dordrecht: Springer. pp. 118−148. ISBN 9781402053023.
  12. Ferguson, S.; Warny, S.; Escarguel, G.; Mudie, P. J. (2018). "MIS 5–1 dinoflagellate cyst analyses and morphometric evaluation of Galeacysta etrusca and Spiniferites cruciformis in southwestern Black Sea". Quaternary International. 465 (465): 117−129. Bibcode:2018QuInt.465..117F. doi:10.1016/j.quaint.2016.07.035.
  13. Aksu, A. E.; Hiscott, R. N.; Mudie, P. J.; Rochon, A.; Kaminski, M. A.; Abrajano, T.; Yaar, D. (2002). <0004:PHOFTB>2.0.CO;2 "Persistent Holocene outflow from the Black Sea to the Eastern Mediterranean contradicts Noah's Flood hypothesis". GSA Today. 12 (5): 4−10. doi:10.1130/1052-5173(2002)012<0004:PHOFTB>2.0.CO;2.
  14. Aksu, A. E.; Hiscott, R. N.; Kaminski, M. A.; Mudie, P. J.; Gillespie, H.; Abrajano, T.; Yaşar, D. (2002). "Last glacial–Holocene paleoceanography of the Black Sea and Marmara Sea: stable isotopic, foraminiferal and coccolith evidence". Marine Geology. 190 (1−2): 119−149. Bibcode:2002MGeol.190..119A. doi:10.1016/S0025-3227(02)00345-6.
  15. Hiscott, R.N., Aksu, A.E., Mudie, P.J., Marret, F., Abrajano, T., Kaminski, M.A., Evans, J., Çakiroğlu, A.İ. and Yaşar, D., 2007. A gradual drowning of the southwestern Black Sea shelf: evidence for a progressive rather than abrupt Holocene reconnection with the eastern Mediterranean Sea through the Marmara Sea Gateway. Quaternary International, 167, pp.19-34.
  16. Goldberg, S.; et al. (2016). "The timing of the Black Sea flood event: Insights from modeling of glacial isostatic adjustment". Earth and Planetary Science Letters. 452: 178–84. Bibcode:2016E&PSL.452..178G. doi:10.1016/j.epsl.2016.06.016.
  17. Badertscher, S.; Fleitmann, D.; Cheng, H.; Edwards, R. L.; Göktürk, O. M.; Zumbühl, A.; Leuenberger, M.; Tüysüz, O. (2011). "Pleistocene water intrusions from the Mediterranean and Caspian seas into the Black Sea". Nature Geoscience. 4 (4): 236–239. doi:10.1038/ngeo1106.
  18. Aksu, A. E.; Hiscott, R. N.; Yaltırak, C. (2016-10-01). "Early Holocene age and provenance of a mid-shelf delta lobe south of the Strait of Bosphorus, Turkey, and its link to vigorous Black Sea outflow". Marine Geology. 380: 113–137. Bibcode:2016MGeol.380..113A. doi:10.1016/j.margeo.2016.07.003.
  19. Algan, O.; Cagatay, N.; Tchepalyga, A.; Ongan, D.; Eastoe, C.; Gokasan, E. (2001). "Stratigraphy of the sediment infill in Bosphorus Strait: water exchange between the Black and Mediterranean Seas during the last glacial Holocene". Geo-Marine Letters. 20 (4): 209–218. Bibcode:2001GML....20..209A. doi:10.1007/s003670000058.
  20. Goldberg, Samuel L.; Lau, Harriet C. P.; Mitrovica, Jerry X.; Latychev, Konstantin (2016-10-15). "The timing of the Black Sea flood event: Insights from modeling of glacial isostatic adjustment". Earth and Planetary Science Letters. 452: 178–184. Bibcode:2016E&PSL.452..178G. doi:10.1016/j.epsl.2016.06.016.
  21. Yanko-Hombach, Valentina; Gilbert, Allan S; Panin, Nicolae (2007). Dolukhanov, Pavel M (ed.). The Black Sea Flood Question: Changes in Coastline, Climate and Human Settlement. Netherlands: Springer. doi:10.1007/978-1-4020-5302-3. ISBN 978-1-4020-5302-3.
  22. Giosan, Liviu; Filip, Florin; Constatinescu, Stefan (2009-01-01). "Was the Black Sea catastrophically flooded in the early Holocene?" (PDF). Quaternary Science Reviews. 28 (1–2): 1–6. Bibcode:2009QSRv...28....1G. doi:10.1016/j.quascirev.2008.10.012.
  23. "Lonny Lippsett, "Noah's not so big flood", Oceanus magazine". www.whoi.edu. Retrieved 2020-01-29.
  24. Mertens, Kenneth Neil; Bradley, Lee R.; Takano, Yoshihito; Mudie, Petra J.; Marret, Fabienne; Aksu, Ali E.; Hiscott, Richard N.; Verleye, Thomas J.; Mousing, Erik A. (2012-04-16). "Quantitative estimation of Holocene surface salinity variation in the Black Sea using dinoflagellate cyst process length". Quaternary Science Reviews. 39: 45–59. Bibcode:2012QSRv...39...45M. doi:10.1016/j.quascirev.2012.01.026.
  25. Yanchilina, Anastasia G.; Ryan, William B. F.; McManus, Jerry F.; Dimitrov, Petko; Dimitrov, Dimitar; Slavova, Krasimira; Filipova-Marinova, Mariana (2017-01-01). "Compilation of geophysical, geochronological, and geochemical evidence indicates a rapid Mediterranean-derived submergence of the Black Sea's shelf and subsequent substantial salinification in the early Holocene". Marine Geology. 383: 14–34. Bibcode:2017MGeol.383...14Y. doi:10.1016/j.margeo.2016.11.001.
Sources

Further reading
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