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Evidence of Ancient Asteroid Found
Evidence suggests an asteroid hit Argentina 3.3 million years ago, causing regional extinctions and climate change.
By Paul Recer, Associated Press
Start Date: 12/10/98
WASHINGTON (AP) -- An 18-mile-long layer of greenish glass in an Argentine seaside cliff may have been deposited by the fiery impact of a comet or asteroid hitting the Earth 3.3 million years ago, according to researchers.
In a study appearing Friday [Dec 11, 1998] in the journal Science, Peter H. Schultz of Brown University said that the glassy material is consistent with melted rock created by a comet or asteroid impact nearby.
The glassy formation is between Mar del Plata and Miramar, two cities on the central Atlantic coast of Argentina.
At the time of the impact, said Schultz, the site of the deposit would have been far from the ocean, but a shifting shoreline has now put it right at the coast. The crater created by the impact, said Schultz, is probably somewhere offshore, but it has not yet been found.
Schultz said geologic deposits just below the glass layer contain fossils of some 36 different types of animals that became extinct around the time of the impact. However, there is insufficient evidence to prove that a collision with a space boulder actually caused the extinctions, he said.
A widely accepted theory is that a six-mile-wide asteroid smashed into the Earth 65 million years ago and led to the demise of the dinosaurs. The impact was large enough to cause major, global disruptions in weather, it's believed.
But the Argentine event came millions of years later and was much smaller.
"This was mostly a local event," said Schultz. "It may have been small enough to cause regional damage and extinctions and may have triggered a climate change."
Among the animals that disappeared after the Argentine impact, he said, were some types of ground sloths, some hoofed mammals, a giant armadillo and a large meat-eating bird.
There is geological evidence, said Schultz, that the air and ocean temperatures also cooled quickly about 3.3 million years ago. But, again, he said more research is needed to determine whether the comet or asteroid impact caused the climate change.
[Disclaimer: This article is copyright (c) The Associated Press. The information contained in AP news reports may not be published, broadcast, rewritten or otherwise distributed without the prior written authority of The Associated Press. This text is posted in the public interest.]
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