Many ancient and modern cultures have creation myths involving flood legends 
similar to the the Bible's story of Noah's Ark. Thinkers over the centuries, 
including Leonardo da Vinci, have debated whether the stories were true. 

In the past few years it has become popular to believe they were – that a 
primordial flood really happened. Recent studies claim to back it up the notion 
scientifically; for instance, there are findings that a that a titanic flood 
created the Black Sea in the Middle East 7,500 years ago. 

But a better explanation may exist, a physicist says.

http://www.world-science.net/exclusives/040906_noahfrm.htm