BTW, I believe the 'great flood' in many western mythologies including the Bible is meant to be based on the creation of the Mediterranean

Actually, there was an article in the Cincinnati Enquirer recently concerning the Great Flood, sort of. The man who used his submarine and little roving sea-pod to locate and explore the remains of Titanic has searched the bottom of the Black Sea and found what appears to be an ancient city.

If this proves to be true, then this would make the creation of the Black Sea an explanation for the Great Flood. A city in a valley being completely flooded out of existence would definitely be a cause for commotion. Both the Greek and Hebrew religions include a monstrous flood (Noah, for the Bible, of course, and the story of Baucis and Philemon for the Greeks). Both cultures were located reasonably close to the Black Sea and they interacted quite a bit, so this would explain the existence of many parallel stories.