Navigation Links
Research team says extraterrestrial impact to blame for Ice Age extinctions

What caused the extinction of mammoths and the decline of Stone Age people about 13,000 years ago remains hotly debated. Overhunting by Paleoindians, climate change and disease lead the list of probable causes. But an idea once considered a little out there is now hitting closer to home.

A team of international researchers, including two Northern Arizona University geologists, reports evidence that a comet or low-density object barreling toward Earth exploded in the upper atmosphere and triggered a devastating swath of destruction that wiped out most of the large animals, their habitat and humans of that period.

The detonation either fried them or compressed them because of the shock wave, said Ted Bunch, NAU adjunct professor of geology and former NASA researcher who specializes in impact craters. It was a mini nuclear winter.

Bunch and Jim Wittke, a geologic materials analyst at NAU, are co-authors of the paper, which fingers an extraterrestrial impact 12,900 years ago for the mass extinctions at the end of the Ice Age. The paper was just released online in the Proceedings of the National Academy of Sciences. The research team includes several members of the U.S. National Academy of Sciences and researchers from Hungary and the Netherlands.

No one has found a giant crater in the Earth that could attest to such a cataclysmic impact 13,000 years ago, but the research team offers evidence of a comet, two and a half to three miles in diameter, that detonated 30 to 60 miles above the earth, triggering a massive shockwave, firestorms and a subsequent drastic cooling effect across most of North America and northern Europe.

The comet may have broken up into smaller pieces as it neared the Earth and then these pieces detonated in various places above two continents, Bunch said.

The evidence for multiple detonations comes from a four-inch-thick black mat of carbon-rich material that appears as far north as Canada, Greenland and Europe to as far south as the Channel Islands off the coast of California and eastward to the Carolinas. Two sites exist in Arizona at Murray Springs and Lehner Ranch, both near Sierra Vista.

Evidence of mammoths and other megafauna and early human hunters, known as the Clovis culture, are found beneath the black mat but are missing entirely within or above it. This led the research team to conclude an extraterrestrial impact wiped out many of the inhabitants of the Late Pleistocene. Bunch notes that some animals may have survived in protected niches.

The black mat was formed by ponding of water and algal blooms and contains carbon, soot and glassy carbonremnants of burned materials. Some of these remnants are extraterrestrial in nature. For example, the research team has identified fullerenes, spherical carbon cages resembling a soccer ball, which are formed in shock events outside the Earths atmosphere. Trapped inside the fullerenes is a concentration of helium 3 that is many times greater than what is found in the Earths atmosphere.

The black mat also has turned up nanodiamonds, which are formed in the interstellar medium outside the solar system, by or by a high-explosive detonation.

Either these things came in with the impactor or they were made during impact detonation. We have no other explanation for their presence, Bunch said.

The magnitude of the detonations would have been huge.

A hydrogen bomb is the equivalent of about 100 to 1,000 megatons, Bunch said. The detonations were talking about would be about 10 million megatons. Thats larger than the simultaneous detonation of all the worlds nuclear bombs past and present.

The research team believes the detonations destabilized a vast ice sheet, known as the Laurentide Ice Sheet, that covered most of what was then Canada and the northern United States. Heat from the detonation and firestorms would have melted much of the ice sheet, releasing water vapor into the atmosphere.

The result was rapid cooling of about eight degrees over the next 100 years, Bunch said. The melting of the ice sheet and subsequent climate change would explain the water-based nature of the black mat.

Catastrophic extraterrestrial impacts are not new. Scientists theorize a much larger asteroid impact annihilated the dinosaurs and about 85 percent of the Earths biomass about 65 million years ago. The most recent incident, known as the Tunguska event, occurred in 1908 in Russia. The Tunguska explosion was an airburst of a comet or meteorite estimated at 10-15-megatons that destroyed tens of millions of trees across more than 800 square miles.

Bunch says impact airbursts may be more common than previously thought with possibly two or three such events having occurred over the last 100,000 years. And more are sure to follow.


Contact: Lisa Nelson
Northern Arizona University

Related biology news :

1. Researchers discover way to make cells in the eye sensitive to light
2. Quantum Dots Research Leads to New Knowledge about Protein Binding in Plants
3. Columbia research lifts major hurdle to gene therapy for cancer
4. Researchers find how protein allows insects to detect and respond to pheromones
5. Researchers Uncover Key Step In Manufacture of Memory Protein
6. Research advances quest for HIV-1 vaccine
7. Research on Worms Yields Clues on Aging
8. U of M researcher examines newly emerging deadly disease
9. NYU researchers simulate molecular biological clock
10. Researchers reveal the infectious impact of salmon farms on wild salmon
11. Researchers identify target for cancer drugs
Post Your Comments:
(Date:11/17/2015)... -- Vigilant Solutions announces today that Mr. Dick W. ... --> --> Mr. Boyce ... at TPG Capital, one of the largest global investment ... revenue.  He founded and led TPG,s Operating Group, which ... 1997 to 2013.  In his first role, he served ...
(Date:11/12/2015)... golden retriever that stayed healthy despite having the gene ... new lead for treating this muscle-wasting disorder, report scientists ... and Harvard and the University of São Paolo in ... pinpoints a protective gene that boosts muscle regeneration, ... Children,s lab of Lou Kunkel , PhD, is ...
(Date:11/11/2015)... MedNet Solutions , an innovative SaaS-based eClinical technology company that ... announce that it will be a Sponsor of the ... held November 17-19 in Hamburg , Germany.  ... iMedNet , MedNet,s easy-to-use, proven and affordable eClinical ... able to deliver time and cost savings of up to ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... Oregon , November 25, 2015 ... Market Research Report is a professional and in-depth ... industry.      (Logo: ) ... overview of the industry including definitions, classifications, applications ... is provided for the international markets including development ...
(Date:11/24/2015)... , Nov. 24, 2015  Asia-Pacific (APAC) ... research organisation (CRO) market. The trend of outsourcing ... lower margins but higher volume share for the ... and scale, however, margins in the CRO industry ... (CRO) Market ( ), finds that ...
(Date:11/24/2015)... , Nov. 24, 2015 Cepheid (NASDAQ: ... speaking at the following conference, and invited investors to ... NY      Tuesday, December 1, 2015 at 11.00 ... NY      Tuesday, December 1, 2015 at 11.00 ... Conference, New York, NY      Tuesday, ...
(Date:11/24/2015)... , Nov. 24, 2015 /CNW/ - iCo Therapeutics ("iCo" ... reported financial results for the quarter ended September ... in Canadian dollars and presented under International Financial ... States ," said Andrew Rae , ... regarding iCo-008 are not only value enriching for ...
Breaking Biology Technology: