At Last, the Smoking Gun?

If a comet did in the dinosaurs, where is the giant crater left by its impact? The answer may lie on the coast of the Yucatan Peninsula.

Hurtling through the atmosphere at nearly 70 km per sec. (150,000 m.p.h.), the giant comet struck with catastrophic force, punching a hole some 40 km (25 miles) deep through the earth's crust and into the mantle. The violence of the collision 65 million years ago completely vaporized the 8-km-wide (5 miles) comet and blasted out a tremendous crater. Huge rocks, hurled high into the + air, rained down for hundreds of kilometers. A great fireball rose above the atmosphere, carrying with it vast amounts of pulverized debris.

These finer particles remained suspended, drifting into a globe-enveloping shroud that blocked sunlight for...

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