Developments in Brief : Meteorite or Comet Probably Carved Out 28-Mile-Wide Undersea Crater

Two geologists say a flaming, mile-thick meteorite or comet nucleus apparently crashed into the Atlantic off Nova Scotia 50 million years ago with the impact equivalent to thousands of nuclear warheads.

The explosive collision gouged out a 28-mile-wide crater on the sea floor 125 miles southeast of Nova Scotia and presumably sent monstrous walls of water toward the continent, they said.

Their report, published in a recent issue of the British science journal Nature, is the first on a major extraterrestrial impact in the ocean, although such craters have been identified around the world on land.

Lubomir Jansa of the Bedford Institute of Oceanography at Dartmouth, Nova Scotia, and Georgia Pe-Piper of St. Mary’s University, Halifax, Nova Scotia, said study of sediments around the crater should provide “a unique opportunity” to see how an oceanic impact could affect neighboring life.

Many researchers believe that dinosaurs and many other forms of life were wiped out 65 million years ago when an even larger object smashed into Earth, kicking up a global cloud of dust that presumably blocked out the sun for months.

Jansa said the explosion was so powerful that the ocean at the impact site probably was opened momentarily and the water vaporized.

The ocean at that time was estimated to be 900 feet deep. What remains today in water 370 feet deep is a crater on the sea bottom at least 28 miles in diameter and 1.7 miles deep, Jansa said. The wall of the crater appears to be severely eroded, presumably from the rush of water back into the crater.