Mar 17, 2011 10:14 GMT  ·  By
The Black Sea is connected to the Sea of Marmara and the Aegean Sea portion of the Mediterranean Sea via the Bosporus Strait (lower left)
   The Black Sea is connected to the Sea of Marmara and the Aegean Sea portion of the Mediterranean Sea via the Bosporus Strait (lower left)

According to the latest archaeological evidence, it would appear that the Black Sea basin was heavily battered by numerous floods over the past hundreds of thousands of years. Clues that this happened were discovered on the walls of caves in surrounding countries.

In a new study, an international collaboration of scientists took samples of cave stalagmites, and analyzed their chemical and geological composition. This allowed the experts to create the most up-to-date record of what happened in the basin over the last geological period.

The resulting dataset covered the past 670,000 years. The team found that the Mediterranean Sea rushed over the Black Sea basin at least 12 times during this tumultuous period, experts report online in the March 13 issue of the top journal Nature Geoscience.

This sea is located inland, marking the separation between eastern Europe, western Asia, and the near East. It is bordered by Bulgaria, Georgia, Romania, Russia, Turkey, and Ukraine. The new study indicates that Turkey was the most severely affected by the ancient floods.

“It’s a very dynamic region,” explains Dominik Fleitmann, a coauthor of the Nature research paper, quoted by Science News.

Researchers first started suspecting that the Black Sea had a rough past when they looked at fossils and mineral samples collected from its basin. Despite all this, the area was largely ignored until now.

For the new work, experts set up camp near the Turkish cave Sofular, which lies some 10 kilometers away from the southern shores of the Black Sea, says Fleitmann, who is a geologist at the University of Bern, in Switzerland.

The reason why this cave was so interesting to experts is because its stalagmites were largely formed from precipitations that evaporated from the nearby sea. The chemical signatures of how the water used to look like were inscribed in stone as the stalagmites petrified.

These records span back hundreds of thousands of years, although some of them have gaps spanning tens of thousands of years. They indicate that the Mediterranean Sea overflowed through the Bosporus Strait 12 times in the past 670,000 years.

The Black Sea is connected to the Aegean Sea portion of the Mediterranean through the Sea of Marmara. In turn, the latter is located between the Bosporus and Dardanelles Straits.

Geological records show that waters from the Mediterranean overflowed both these straits and the Sea Marmara, reaching the Black Sea in sufficient quantities to cause floods, and to batter Turkey.

Even the Caspian Sea, located several hundreds of kilometers to the east of the Black Sea, overflowed into the latter at least seven times during the same time frame.

“When you start melting the ice, global sea level rises. And the same was true for the Caspian Sea,” Fleitmann says, explaining that the overflows were connected to glacier dynamics.