The Mediterranean Sea swells and seawater surges…

The Mediterranean Sea swells and seawater surges northward, slicing through the natural dam at the Bosporus in what is now Turkey sometime around seven thousand five hundred years ago, according to a theory proposed in the late 1990s by Columbia University geologists William Ryan and Walter Pitman.

According to this theory, around 5500 BCE, a wall of seawater, funneled through the narrow Bosporus, hit the low-lying freshwater lake with two hundred times the force of Niagara Falls.

Fueled by the infinite waters of the Atlantic, Pacific and Indian Oceans, the seawaters rushed in for the next year or so, maybe longer.

Under this scenario, each day the lake level would have risen about six inches, flooding coastal farms, inundating whatever communities might have existed and forming what will be called the Black Sea, ultimately increasing the lake's area by a third.

Surviving marine life was driven into the newly abbreviated estuaries of the Danube, Dniester, Dnieper, Don, and Bug Rivers.

In flatter coastal areas, the shoreline may have advanced as much as a mile a day.

This hypothesis has been the subject of considerable discussion, and a news article from National Geographic News in February 2009 reported that the flooding might have been "quite mild.” While it is agreed by all that the sequence of events described did occur, there is debate over their suddenness and magnitude.

In particular, if the water level of the Black Sea were initially higher, the effect of the spillover would have been much less dramatic.

According to a study by Giosan et al., the level in the Black Sea before the marine reconnection was thirty meters below present sea level, rather than the eighty meters 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, around 7400 BCE rather than the originally proposed 5600 BCE.