Filling in cosmic holes.

• Author: Werner, Lou
• Position: Dinosaur extinction theory - Americas !Ojo!

A recent scientific finding has given credence to a theory, debated for over a decade, about the mass extinction of dinosaurs. Evidence of the occurrence of a cosmic catastrophe--sometime between the Cretaceous and Tertiary periods some sixty-five million years ago--began to mount in 1980 when geologists at the University of Berkeley in California discovered large amounts of the rare metal iridium, an element more common in outer space than on our planet. Subsequently, they found "shocked" quartz grains, caused only by episodes of intense stress, followed by the unearthing of ancient soot deposits, an indication of large scale burning.

Slowly a theory took hold about a huge meteorite crashing into Earth, screening out the sun with air borne debris and igniting worldwide forest fires. But there was a missing link. Where was the impact crater, exactly the right age and big enough, to provoke such devastation? Finally the crater has been identified--deep under the Yucatan Penninsula's northern coastline--and precisely dated.

"It looks to me like this is the smoking gun," said geologist Walter Alvarez, who along with his father Luis and two others is the theory's original proponent. But the gun has long stopped smoking. And visitors will have a hard time finding the crater, now dubbed Chicxulub (A Mayan word for "devil's tail") in honor of the nearby town, buried as it is...