Support: comet impact may have triggered the Younger Dryas period
Baku, October 2 (AZERTAC). Did a massive comet explode over Canada 12,900 years ago, wiping out both beast and man in North America and propelling the earth back into an ice age?
That’s a question that has been hotly debated by scientists since 2007, with the University of South Carolina’s Topper archaeological site right in the middle of the comet impact controversy. However, a new study published in the Proceedings of the National Academy of Sciences (PNAS) provides further evidence that it may not be such a far-fetched notion.
Albert Goodyear, an archaeologist in USC’s College of Arts and Sciences, is a co-author on the study that upholds a 2007 PNAS study by Richard Firestone, a staff scientist at the Department of Energy’s Lawrence Berkeley National Laboratory.
Firestone found concentrations of spherules (micro-sized balls) of metals and nano-sized diamonds in a layer of sediment dating 12,900 years ago at 10 of 12 archaeological sites that his team examined. The mix of particles is thought to be the result of an extraterrestrial object, such as a comet or meteorite, exploding in the earth’s atmosphere. Among the sites examined was USC’s Topper, one of the most pristine U.S. sites for research on Clovis, one of the earliest ancient peoples.
Younger-Dryas is what scientists refer to as the period of extreme cooling that began around 12,900 years ago and lasted 1,300 years. While that brief ice age has been well-documented - occurring during a period of progressive solar warming after the last ice age - the reasons for it have long remained unclear. The extreme rapid cooling that took place can be likened to the 2004 sci-fi blockbuster movie “The Day After Tomorrow.”
Firestone’s team presented a provocative theory: that a major impact event - perhaps a comet - was the catalyst. His copious sampling and detailed analysis of sediments at a layer in the earth dated to 12,900 years ago, also called the Younger-Dryas Boundary (YDB), provided evidence of micro-particles, such as iron, silica, iridium and nano-diamonds. The particles are believed to be consistent with a massive impact that could have killed off the Clovis people and the large North American animals of the day. Thirty-six species, including the mastodon, mammoth and saber-toothed tiger, went extinct.
The scientific community is rarely quick to accept new theories. Firestone’s theory and support for it dominated the annual meeting of the American Geophysical Union and other gatherings of Paleoindian archaeologists in 2007 and 2008.
However, a 2009 study led by University of Wyoming researcher Todd Surovell failed to replicate Firestone’s findings at seven Clovis sites, slowing interest and research progress to a glacial pace. This new PNAS study refutes Surovell’s findings with its lack of reported evidence.
LeCompte began his independent study in 2008 using and further refining Firestone’s sampling and sorting methods at two sites common to the three studies: Blackwater Draw in New Mexico and Topper. He also took samples at Paw Paw Cove in Maryland, a site common to Surovell’s study.
At each site he found the same microscopic spherules, which are the diameter of a human hair and distinct in appearance. He describes their look as tiny black ball bearings with a marred surface pattern that resulted from being crystallized in a molten state and then rapidly cooled. His investigation also confirmed that the spherules were not of cosmic origin but were formed from earth materials due to an extreme impact.
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