Dino-Era Crater Probed for Clues to Mass Extinction

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"People have a hard time understanding the scale of this impact," Kring said. "It moved millions of tons of rock, some of it more than 60 miles (97 kilometers)."

Material 20 miles (32 kilometers) beneath the surface was affected by the shock wave. A large part of Earth's crust was uplifted and folded by the blast.

Poisonous gases, dust, smoke, and fire from the impact blotted out the sun, lowered temperatures, and contaminated the air for months or years, killing more than 75 percent of the plant and animal species in existence.

Closer Monitoring

Wary of another such calamity, astronomers have begun a search for all large "Near Earth Objects" that might be on a collision course with our planet.

On January 7, for example, they spotted an asteroid the size of three football fields that streaked within 500,000 miles (804,672 kilometers), twice the distance to the moon.

If a space rock is detected early enough, scientists hope they will be able to deflect it with a nuclear-armed missile. Even a slight change of course could be enough for a far-off object to miss Earth.

According to Powell, who is not a member of the Chicxulub project, the drilling may clear up some mysteries, such as whether the space intruder was a comet or an asteroid.

Asteroids are rocky objects orbiting between Earth and Jupiter. Comets are balls of ice and frozen gas from beyond Pluto that periodically swoop through the solar system. Comets are considered more dangerous than asteroids because their enormous speed multiplies their power.

In addition, Powell said the drillers might find traces of sulfur-rich rocks in the crater that could help explain why the atmosphere poisoned so many living creatures.

Copyright 2002, The Record (Bergen County, New Jersey)

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