Younger Dryas impact event
The Younger Dryas impact event is the name of a hypothesized impact event at the beginning of the Younger Dryas cold spell about 10,900 BCE. The impact seems to have occurred near the North American Great Lakes; the bolide may have disintegrated in the air.
Evidence
The evidence for such an impact event is a layer of unusual materials (Nanodiamonds, magnetic grains, carbon spherules, magnetic spherules, charcoal, soot, fullerenes enriched in Helium 3, etc.) at the very bottom of the "black mat" of organic material that marks the beginning of the Younger Dryas.[ News article in Nature ]
It is hypothesized that this impact event brought about the extinction of many North American large mammals. These animals included camels, mammoths, the giant short-faced bear and numerous other species. The markers for the impact event also appear at the end of the Clovis culture.[ Includes links to abstracts.]
2007/2008 meetings
Scholars have actively debated the controversial theory. On May 24, 2007, a session at the spring 2007 joint assembly of the American Geophysical Union in Acapulco, Mexico was held to discuss this hypothesis and reveal the evidence.
The theory also drew new scrutiny in March 2008 at the annual meeting of the Society for American Archaeology in Vancouver, Canada.
PNAS publications, pro and contra
On September 27, 2007, a paper presenting the findings of the Acapulco group was pre-published online at the Proceedings of the National Academy of Sciences website. According to the study, the impact event may have led to an immediate decline in human populations in North America at that time.[ ]
Almost a year later, a study published in August 2008 states "The results of the analyses were not consistent with the predictions of extraterrestrial impact hypothesis. No evidence of a population decline among the Paleoindians at 12,900 ± 100 calBP was found. Thus, minimally, the study suggests the extraterrestrial impact hypothesis should be amended." [B Buchanan, M Collard & K Edinborough 2008. "Paleoindian demography and the extraterrestrial impact hypothesis " PNAS August 19, 2008 vol. 105 no. 33 11651-11654 doi: 10.1073/pnas.0803762105 ]
See also
 Pleistocene megafauna
Holocene extinction event
References
External links
Video of the AGU Press Conference announcing the discovery
|
|
|
|
This section is sponsored by:
Laptops
Find a great deal on a Laptop Computer by browsing our Laptop Computer listings.
www.LaptopComputersInfo.com
Top Laptop Computer
Need Top Laptop Computer at Low Price? Compare &Deal Today!
1st-in-Computers.com
Laptops
Laptops Info
www.givemearticles.com
laptops
Don't just search for laptops, find results.
www.ask.com
laptops
Search for laptops here.
www.aywoh.com
Laptops
Find articles, advice and resources on laptops.
www.experttopics.com
laptops
Don't just search for laptops, find results.
wwwAsk.com
|
