The Late Quaternary history of connection of the Black Sea to the Eastern
Mediterranean has been intensely debated. Ryan, Pitman and coworkers
advocate two pulses of outflow from the Black Sea to the world ocean at
~16–14.7 ky BP and ~11–10 ky BP. From ~14.7–11 ky BP and from ~10–8.4
ky BP, they suggest that the level of the Black Sea fell to ~ -100 m. At 8.4 ky
BP, they further claim that a catastrophic flood occurred in a geological
instant, refilling the Black Sea with saline waters from the Mediterranean. In
contrast, we continue to gather evidence from seismic profiles and dated cores
in the Marmara Sea which demonstrate conclusively that the proposed flood
did not occur. Instead, the Black Sea has been at or above the Bosphorus sill
depth and flowing into the world ocean unabated since ~10.5 ky BP. This
conclusion is based on continuous Holocene water-column stratification
(leading to sapropel deposition in the Marmara Sea and the Aegean Sea),
proxy indicators of sea-surface salinity, and migration of endemic species
across the Bosphorus in both directions whenever appropriate hydrographic
conditions existed in the strait. The two pulses of outflow documented by
Ryan, Pitman and coworkers find support in our data, and we have modified our earlier interpretations so that these pulses now coincide with the
development of mid-shelf deltas: \Delta 2 (16–14.7 ky BP) and \Delta 1 (10.5–9 ky BP)
at the southern end of the Bosphorus Strait. However, continued Black Sea
outflow after 9 ky BP prevented the northward advection of Mediterranean
water and the entry of open-marine species into the Black Sea for more than
1000 years. Sufficient Mediterranean water to change the Sr-isotopic
composition of slope and shelf water masses was not available until ~8.4 ky
BP (along with the first arrival of many varieties of marine fauna and flora),
whereas euryhaline molluscs did not successfully populate the Black Sea
shelves until ~7.15 ky BP. Instead of relying on catastrophic events, we
recognize a slow, progressive reconnection of the Black Sea to the world
ocean, accompanied by significant time lags
