It's alternative fiction and comes from here:

[www.atlantisrising.com]

Yet, knowing this, geologists are hard pressed to explain why there existed a fourteen-foot layer of silt sediment around the base of the Pyramid, a layer which also contained many seashells, and the fossil of a sea cow, all of which were dated by radiocarbon methods to 11,600 B.P. (Before Present) plus or minus 300 years.

The article is total fiction throughout ! The interesting thing is that 14C dating was developed until after WWII (Before Present (BP) dates are related to 1950) so for stuff to have been dated by that method it had to be around at that time.

Petrie spent a while there in the 1880s and didn't mention it !

John