There are just some very minute fossils. These were the survivors in the ocean. This layer represents about 5,000 years, said the scientist, and then the core samples show evidence of renewed life. Although the impact occurred in the southern Gulf of Mexico, Norris went to the Atlantic Ocean, near the edge of the continental shelf. He said the theorized waves from the impact would have washed completely across Florida, depositing debris in the Atlantic.
Quotes are from media sources.