http://www.cnn.com/2010/US/09/15/gulf.oily.layer/index.html?npt=NP1

"A team of researchers in the Gulf of Mexico say they found an oily layer as thick as two inches coating the sea floor in some places, and they believe it may be from the BP spill.

"I think what we're seeing is oil that was on the surface, that has sedimented down to the bottom," said Samantha Joye of the University of Georgia.

Speaking by phone from a research vessel about 30 miles southeast of the former oil well, Joye said about a dozen core samples of the seabed were taken, at distances ranging from two miles to 80 miles from the site of the BP rupture.

She described the oil as "flocculent," fluffy like fallen snow, and ranging in thickness from less than a quarter-inch to more than two inches."