Sonar imagery revealed the smooth beach (bottom), the choppy lake bed (mid-section) and a smooth sandbar (top) that were features of the Black Sea before the flood

In July of 1999, Ballard and his colleagues began mapping the floor of the Black Sea, looking for the once-fertile plains. Going on Ryan and Pitman's estimates that sea levels rose roughly 150 meters during the flood, Ballard and his colleagues searched for what would have been the ancient coastline of the freshwater lake.

Using sonar and global positioning system (GPS) to navigate, Ballard swept his ship back and forth through the target area, creating the first detailed profile of the sea floor. As the ship's computer processed the sonar data, the images scrolled across the ship's monitors. Precisely where Ryan and Pitman said it would be, the sonar images revealed a broad flat plain spanning some 20 miles from the present day coastline out to sea. Adjacent to this plain lies the ancient lakebed. Farther out, a sand bar echoes the shape of the original shoreline.

The sonar imaging left little doubt the Black Sea had once been smaller. But there were still more pieces of this puzzle to be found.

From Fresh to Salty

On this same expedition, the scientists dredged the bottom of the Black Sea, bringing up - among other things - a variety of seashells. Though analysis of those seashells would take some time, the results would turn out to be worth the wait.

	Ballard sorts through the items dredged from the bottom, among them the tell-tale shells.

In November 1999, Ballard announced the conclusions to the world. Ballard and his colleagues had collected shells from nine separate species of mollusks, shell-building invertebrates such as snails and clams. Expert analysis by Gary Rosenberg of the Academy of Natural Sciences in Philadelphia revealed that seven of the species were saltwater mollusks, ranging up to 6,800 years old. The other two species, however, were extinct freshwater species that might have lived between 7,460 and 15,500 years ago. These two species proved this body of water must have been fresh until 7,460 years ago, providing more- and incontrovertible- evidence of an influx of saltwater from the Mediterranean Sea.
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Photos: Institute for Exploration