Ancient splash in the Atlantic.

A drilling project along the Virginia coast has uncovered signs that a meteorite slammed into the Atlantic Ocean 40 million years ago, letting loose a huge wave perhaps more than 100 feet high. The tsunami apparently gouged out of the seafloor a region about the size of Connecticut, reports C. Wylie Poag of the U.S. Geological Survey in Woods Hole, Mass.

Poag and his colleagues devised their wave theory to explain a 200-foot-thick layer of boulders they have found in three locations, buried under 1,200 feet of sediment. Within the boulder layer lie glassy rocks called tektites and mineral grains bearing shock features - indications that a meteorite hit nearby. Poag suggests the meteorite crashed into the submerged continental shelf, creating a wave that ripped the seafloor into 3-foot boulders near present-day Virginia.

The scientists first discovered signs of this impact eight years ago when a deep-sea drilling project off the coast of Atlantic City, N.J., pulled up tektites and shocked mineral grains some 40 million years old. The new findings substantiate the earlier impact evidence and suggest that the crash occurred off the Mid-Atlantic Coast.

Many scientists attribute the mass extinction of 65 million years ago to a large meteorite or comet that walloped Earth at that time. Poag's proposed meteorite was not large enough to cause a mass extinction 40 million years ago.