• In the Sumerian city of Ur, 3 meters deep, perfectly clean clay, uniform throughout, the texture of which showing that it had been laid there by water was found. The clay was void of signs of habitation. It does, however, show some evidence of a flood. It might have been either a river flood or an ocean flood.
• Kurt Lambeck, from the Australian national university created a detailed study showing that the present day level of the sea was reached 6,000 years ago, and then went up an extra 1-2 meters, flooding the low-lying areas of lower mesopotamia before receding once more. This is likely what deposited the clay. This is a miniature episode of what would have been happening worldwide, and is now called the Flandrian transgression.
Although in Eridu, Archeologists claim they found ‘virgin soil’ with no trace of a flood evident, Ur, which is on higher ground, shows evidence of a flooding. Also, due to the odd way that the soil in Fertile crescent moves, it is easy to believe virgin soil has been found when in fact underneath the soil lies older settlements. It is also possible that some other raised land masses may have blocked the flood and forced the water to go around the landmass.

Source: Graham Hancock, Underworld (Yes, I’m using this author’s information a lot. I’m going to use other sources soon, but first I should finish the book.)