Woolly mammoths wiped out by climate change after cosmic impact: Study
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Last Updated: Tuesday, May 21, 2013, 12:19
  
Washington: A new research has found evidence of a major cosmic event near the end of the Ice Age, which resulted in a climate change that forced many species, including woolly mammoths, to die.

Something - global-scale combustion caused by a comet scraping our planet's atmosphere or a meteorite slamming into its surface - scorched the air, melted bedrock and altered the course of Earth's history. Exactly what it was is unclear, but this event jump-started what Kenneth Tankersley, an assistant professor of anthropology and geology at the University of Cincinnati, calls the last gasp of the last ice age.

"Imagine living in a time when you look outside and there are elephants walking around in Cincinnati. But by the time you're at the end of your years, there are no more elephants. It happens within your lifetime," Tankersley said.

Tankersley explained what he and a team of international researchers found might have caused this catastrophic event in Earth's history in their research.

This research might indicate that it wasn't the cosmic collision that extinguished the mammoths and other species, Tankersley said, but the drastic change to their environment.

Tankersley found a treasure trove of answers to some of those questions in Sheriden Cave in Wyandot County, Ohio. It's in that spot, 100 feet below the surface, where Tankersley has been studying geological layers that date to the Younger Dryas time period, about 13,000 years ago.

In studying this layer, Tankersley found ample evidence to support the theory that something came close enough to Earth to melt rock and produce other interesting geological phenomena. Foremost among the findings were carbon spherules. These tiny bits of carbon are formed when substances are burned at very high temperatures.

Tankersley said the ones in his study could only have been formed from the combustion of rock.

The spherules also were found at 17 other sites across four continents - an estimated 10 million metric tons' worth - further supporting the idea that whatever changed Earth did so on a massive scale. It's unlikely that a wildfire or thunderstorm would leave a geological calling card that immense - covering about 50 million square kilometres.

Other important findings include:

Micrometeorites: smaller pieces of meteorites or particles of cosmic dust that have made contact with the Earth's surface.

Nano-diamonds: microscopic diamonds formed when a carbon source is subjected to an extreme impact, often found in meteorite craters.

Lonsdaleite: a rare type of diamond, also called a hexagonal diamond, only found in non-terrestrial areas such as meteorite craters.

Tankersley said while the cosmic strike had an immediate and deadly effect, the long-term side effects were far more devastating - similar to Krakatoa's aftermath but many times worse - making it unique in modern human history.

In the cataclysm's wake, toxic gas poisoned the air and clouded the sky, causing temperatures to plummet. The roiling climate challenged the existence of plant and animal populations, and it produced what Tankersley has classified as "winners" and "losers" of the Younger Dryas.

He stated that inhabitants of this time period had three choices: relocate to another environment where they could make a similar living; downsize or adjust their way of living to fit the current surroundings; or swiftly go extinct. "Winners" chose one of the first two options while "losers," such as the woolly mammoth, took the last.

"Whatever this was, it did not cause the extinctions. Rather, this likely caused climate change. And climate change forced this scenario: You can move, downsize or you can go extinct," said Tankersley.

The study was published in the Proceedings of the National Academy of Sciences.

ANI


First Published: Tuesday, May 21, 2013, 12:18


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