An artist's rendering of the moment of impact when an enormous space rock struck the Yucatán peninsula at the end of the Cretaceous.
Click on image for full size
Courtesy of Don Davis, NASA

Revisiting Chicxulub
News story originally written on March 4, 2010

For decades, scientists have known that an enormous space rock crashed into the ocean off the Yucatan Peninsula more than 65 million years ago, resulting in the the K-Pg extinction.

We know that more than half of the plant and animal species on Earth died out then, but we don't know what caused the extinction. Now, a team of 41 scientists from 12 nations has prepared a paper that suggests that the K-Pg extinction was caused by a single impact near what is now Chicxulub, Mexico.

In their paper, the scientists point out that when the asteroid hit the Earth near Chicxulub, it exploded and threw huge amounts of dust and asteroid material into the air. When all of that material settled back to Earth, it formed a clay layer that can still be seen in rocks around the world. Within the layer, scientists have found high levels of iridium. This heavy element is not normally found in high concentrations at Earth's surface, but it is found in asteroids and comets.

The impact between the asteroid and the Earth created a crater that is more than 180 kilometers in diameter. It also caused tsunami, earthquakes and fires; extended (but not total) darkness; cooling temperatures and acid rain. It would have also changed the Earth's climate.

Last modified March 28, 2010 by Jennifer Bergman.

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