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Researcher Says He May Have Proof Comet Over Canada Killed Mammoths


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Bianca
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« on: July 07, 2008, 09:17:14 am »









                      Researcher says he may have proof comet over Canada killed mammoths





David Wylie,
Canwest News Service
Published:
Monday, July 07, 2008

U.S. anthropologist Ken Tankersley is waiting excitedly for lab results that he says may be the missing link proving "beyond a reasonable doubt" the much-debated theory that a massive comet exploded over modern-day Canada 13,000 years ago  scorching swaths of North America, radically changing the continent's climate and leading to the extinction of the woolly mammoth.

The controversial comet theory has been advanced over the past few years by a number of scientists, including Arizona-based geophysicist Allen West. Tankersley recently agreed to work with West, adding he signed on as a skeptic, thinking he'd find evidence disproving the theory.

"I didn't buy it one bit," he told Canwest News Service. "I turned around trying to disprove Alan West and I came up with what potentially is going to be the very best evidence trying to support it."

Tankersley, an assistant professor of anthropology at the University of Cincinnati, said he's confirmed the two Ohio sites he's been investigating have nearly all the traces of a cataclysmic impact  heavy metals from northern Canada, a carbonized layer, animals that had their flesh burned off and a high magnetic signature.

Now he said he believes he's found the missing link  an abundance of micrometeorites, as well as iridium: a silvery-white metal Tankersley calls "a fingerprint of these type of events, whether it's a giant asteroid or a giant comet."

He's sent the samples to an independent lab to be verified. If the tests come back positive, Tankersley said he'll publish a scientific paper on the discovery.

"We have to find those micrometeorites in the deposits as well before we get that beyond reasonable doubt. At that point you have everything you get with an impact," he said.

Scientists have been building the case that a massive comet exploded 12,900 years ago over northern Canada, generating a shock wave and throwing massive amounts of debris, heat and gas into the atmosphere. That, in turn, set wildfires racing across grasslands in southern North America, depriving the mammoths and other grazing animals of food.

The theory states the blast also destabilized the ice sheet that blanketed Canada, sending a flood of melt water pouring into the North Atlantic. An abrupt cooling followed, creating a "mini-ice age" in the Northern Hemisphere, known as the Younger Dryas, which lasted more than 1,000 years.

Tankersley has been collecting gold, silver and diamonds from a dig site and cave in Ohio  all have been traced back to the Canadian Shield. He said there are no natural explanations for how the diamonds ended up at the sites, except they were carried by a massive impact.

One alternative theory is that the diamonds were transported by a glacier. However, Tankersley argued there's no kimberlite in the region  the rock best known for containing diamonds.

"Every rock you can imagine in Canada, we have in Ohio and Indiana, brought down by glaciers, but we have no kimberlite," he said. "So how did these heavy metals get down here?

"Then Alan West, said, 'Well, Ken, I haven't written this up but my proposed area of impact was over a kimberlite bed.'

"All or a sudden now we have a mechanism for getting these heavy minerals down south."

One skeptic said Tankersley's work won't end the debate.

University of Victoria climatologist Andrew Weaver said explaining why the climate changed 13,000 years ago is like a giant puzzle  and sometimes pieces fit temporarily.

"We don't need to explain everything by comets," said Weaver. "I'm not trying to dismiss it, but one has to be very leery when people always like to attribute something to celestial bodies.

"Whatever anyone says this still remains rather controversial. This is certainly not the end."
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