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Planet Earth

Scientist Smackdown: Did a Comet Explode Over Prehistoric North America?

80beatsBy Brett IsraelOctober 19, 2009 4:00 PM

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A

ccording to a theory proposed in 2007, the

explosion of a comet over North America killed off the Clovis people and many of the continent's largest mammals nearly 13,000 years ago. Not so fast, says a new study

published in the Proceedings of the National Academy of Sciences, fueling a WWE-style stare down between the opposing camps. The new report explains that

archaeologists have examined sediments at seven Clovis-age sites across the United States, and found that the concentration of magnetic debris was insufficient to confirm an extraterrestrial impact at that time [Nature News]. The original theory's

evidence came from magnetic microspherules, or cosmic debris, discovered in sediments at 25 locations. However, one of the new study's authors, Todd Surovell, said that even after 18 months of sedimentary analysis and hundreds of hours peering into a microscope, he could find no evidence of microspherulesto support the the exploding comet theory. Snap. But the research team that proposed the comet theory isn't backing down. "

Their study doesn't negate our hypothesis," says James Kennett, a palaeoceanographer at the University of California, Santa Barbara... Another co-author, geophysicist Allen West of Prescott, Arizona, says that Surovell's group didn't use the correct techniques to extract, identify and quantify the microspherules [Nature News]. Burn.

This isn't the first challenge to the North American comet theory. A study in February found no evidence of burning biomass that a comet explosion, and the resulting continent-wide fire, would have produced.

Kennett, one of the researchers who originally proposed the theory, responded by saying the contradictory studies are "flawed" and published a study in August on his team's finding of

nanometer-sized diamonds, supposedly created during the comet's impact. Scientists on both sides of the scuffle have new research scheduled for publication soon, so stay tuned! Related Content: 80beats: Jupiter Grabbed a Comet for 12 Years, Then Flung It Back Out 80beats: Comets Not So Likely to Smash Into Earth and Kill Us All 80beats: Space Probe Soon to Study Mercury’s Comet-Like “Tail”

Image: NASA

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