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Comet attack equal to atom bombs: scientists
Source: Agencies |
January 4, 2009, Sunday
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Print Edition
Print Edition
TINY diamonds sprinkled across North America suggest a "swarm" of comets hit the Earth around 13,000 years ago, kicking up enough disruption to send the planet into a cold spell and drive mammoths and other creatures into extinction, scientists have reported.
The gems suggested an event that would transcend anything Biblical - a series of blinding explosions in the atmosphere equivalent to thousands of atomic bombs, the researchers said on Friday.
The so-called nano-diamonds were made under high-temperature, high-pressure conditions created by cosmic impacts, similar to an explosion over Tunguska in Siberia that flattened trees for kilometers in 1908.
Doug Kennett of the University of Oregon and colleagues found the little diamonds at sites from Arizona to South Carolina and into Alberta and Manitoba in Canada.
They were buried at a level that corresponded to the beginning 12,900 years ago of the Younger Dryas, a 1,300-year-long cold spell during which North American mammoths, saber-toothed cats, camels and giant sloths became extinct.
The Clovis culture of American Indians also appeared to have fallen apart during this time.
Bones of these animals, and Clovis artifacts, were abundant before this time. Excavations showed a dark "mat" of carbon-rich material separated the bones and artifacts from emptier and younger layers.
The researchers' finding were announced in the journal Science.
The gems suggested an event that would transcend anything Biblical - a series of blinding explosions in the atmosphere equivalent to thousands of atomic bombs, the researchers said on Friday.
The so-called nano-diamonds were made under high-temperature, high-pressure conditions created by cosmic impacts, similar to an explosion over Tunguska in Siberia that flattened trees for kilometers in 1908.
Doug Kennett of the University of Oregon and colleagues found the little diamonds at sites from Arizona to South Carolina and into Alberta and Manitoba in Canada.
They were buried at a level that corresponded to the beginning 12,900 years ago of the Younger Dryas, a 1,300-year-long cold spell during which North American mammoths, saber-toothed cats, camels and giant sloths became extinct.
The Clovis culture of American Indians also appeared to have fallen apart during this time.
Bones of these animals, and Clovis artifacts, were abundant before this time. Excavations showed a dark "mat" of carbon-rich material separated the bones and artifacts from emptier and younger layers.
The researchers' finding were announced in the journal Science.
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