Science / Medicine : Tiny Diamonds Bolster Meteorite Disaster Theory

A cache of tiny diamonds is the latest evidence that a meteorite smashed into Earth about 65 million years ago, an event some scientists say led to extinction of the dinosaurs. Such diamonds, smaller than some viruses, are often seen in meteorites recovered on Earth.

Canadian researchers reported last week in the British journal Nature that they found some in sediment formed at the time it is thought that the meteorite hit. That suggests the diamonds were in the debris that was blown far from the impact and then settled back to Earth. No diamonds appeared in sediment that formed just before or after the believed impact, according to David Brez Carlisle of Environment Canada in Ottawa and Dennis Braman of the Royal Tyrrell Museum of Paleontology in Drumheller, Canada.

The diamonds are far too small to have commercial value, Carlisle said. A thousand of them strung end to end “would just about make a girdle for a bacterium if a bacterium had a waist.” The diamonds appeared in a layer of gray clay found in near Drumheller in Alberta.

The meteorite theory of extinction suggests that one or more asteroids or comets struck the Earth, kicking up enough debris to block out sunlight and kill off food supplies, or perhaps that the impact caused lethal acid rain or worldwide forest fires. While some scientists have argued that the extinction was caused by volcanic eruptions, the new discovery seems to eliminate that possibility because such diamonds would not be produced in an eruption.