page_title: Black Sea deluge hypothesis
section_title: Controversy
hierarchical_section_title: Black Sea deluge hypothesis / Controversy
context_page_description: 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.
context_section_description: 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. The Black Sea area has been sealed off and reconnected numerous times  during the last 500,000 years.
  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. 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.
  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.
  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.
  According to a 2009 study by Liviu Giosan, Florin Filip, and Stefan Constatinescu, 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. An August 2009 article, based on this same study, reported that the flooding could have been "not so big".
  A 2012 study based on process length variation of the dinoflagellate cyst Lingulodinium machaerophorum shows no evidence for catastrophic flooding.
  A 2015 study reviewed the evidence accumulated and acknowledged a "fast transgression" lasting between 10 and 200 years.
caption: The Post-Glacial Sea Level.
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