Posted on 09/25/2007 12:58:19 PM PDT by blam
Contact: Lisa Nelson
Lisa.Nelson@nau.edu
928-523-6123
Northern Arizona University
Research team says extraterrestrial impact to blame for Ice Age extinctions
A colorized scanning electron microscope image of a glassy carbon sphere that contains evidence of extraterrestrial impact. The sphere measures about .012 inches in width.
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.”
Ted Bunch of the Northern Arizona University geology department is a member of an international team that has found evidence of an extraterrestrial impact that may have wiped out the...
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 carbon—remnants 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 Earth’s atmosphere. Trapped inside the fullerenes is a concentration of helium 3 that is many times greater than what is found in the Earth’s 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 we’re talking about would be about 10 million megatons. That’s larger than the simultaneous detonation of all the world’s 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 Earth’s 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.
### NOTE: The work by an international team of researchers that points to a comet or low-density asteroid as the cause of the massive Ice Age extinctions has attracted widespread attention. The National Geographic Channel, which was on campus in May to film Northern Arizona University’s Ted Bunch and Jim Wittke, will air a documentary on the research on Sunday, Oct. 7, at 10 p.m. EST. Discover magazine cited Bunch in an article on “The Great American Extinction” that appeared in the August issue.
The book posted above pertains to a similar model (yes, I’ve finished it Blam, believe me, you *do* want it); those authors look at various current large lakes (including Lake Michigan) and other large bodies of water (Hudson’s Bay) for earlier supporting research on where the impacts happened. There’s quite a bit about the Carolina Bays, offshore Carolina Bays, and similar (basically identical) formations throughout the US and Canada, and used their orientations to find the impact points. Before they did that, they’d found for evidence for extraterrestrial origin of the parent impacts (the bays being ejecta craters), and the “black mat” which caps the Clovis period. Interestingly enough, the black mat appears to correspond to a similar, algal growth phenomenon which left fossil traces after the Permian-Triassic and Cretaceous-Tertiary events.
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:’) None of the known *uniformitarian* models can do it, but those are eroding away. ;’)
Maybe Howard A. Boardman had it right...
Hole filler.......
Look at Hudson’s Bay and the entry drag of James Bay. The low angle impact gouged James Bay on the way in and holed out as Hudson’s Bay.
Thanks for all the pings.... This one ...I was thinking in biblical terms until I got to the thread. :)
have you (or anyone) seen research into possible location or area of any underwater crater from the presumed 540AD event? The muddy rain mentioned in some sources implies a water burst/impact, but presumably it is quite small given the effect, I don’t know if it would even leave a crater.
My research says they all drowned! And during a rather short span of time. They weren’t built real well for treading water.
The Lost Americans
by Frank C. Hibben
“In many places the Alaskan muck blanket is packed with animal bones and debris in trainload lots.”
“Within this mass, frozen solid. lie the twisted parts of animals and trees intermingled with lenses of ice and layers of peat and mosses. It looks as though in the middle of some catacystimic catastrophe. . . the whole Alaskan world of living animals and plants was suddenly frozen in mid- motion in a grim charade” (Frank C. Hibben, The Lost Americans, New York; Apollo Editions, 1961. pp. 90, 91).
“Tendons, ligaments, fragments skin and hair, hooves - all are preserved in the muck. In some cases, portions of animal flesh have been preserved. Bones of mammoths, mastodons, bison, horses, wolves, bears and lions are hopelessly entangled! One author counts 1,766 jaws and 4,838 meta- podials from ONE species of bison in a small area near Fairbanks, Alaska, alone. Archaeologist Hibben saw with his own eyes - and smelled with his own nostrils - the specter of death. North of Fairbanks, Alaska, he saw bulldozers pushing the melting muck into sluice boxes for the extraction of gold. As the dozers’ blades scooped up the melting gunk, mammoth tusks and bones “rolled up like shavings before a giant plane.” The stench of rotting flesh -tons of it - could be smelled for miles around.
Hibben and his colleagues walked the pits for days. As they followed the bulldozers they discovered perfect bison skulls with horns attached, mammoth skin with long black hair and jumbled masses of bones.
Appalling Death in Alaska
“Mammals there were in abundance, dumped in all attitudes of death. Most of them were pulled apart by some unexplained prehistoric catastrophic disturbance. Legs and torsos and heads and fragments were found together in piles or scattered separately” ((ibid., p.97). Logs, twisted trees, branches and stumps were interlaced with the mammal menagerie. The signs of sudden death were legion.
For example, in the Alaskan muck, stomachs of frozen mammoths have been discovered. These frozen stomach masses contain the leaves and grasses the animals had just eaten before death struck. Seemingly, no animal was spared.
“The young lie with the old, foal with dam and calf with cow. Whole herds of animals were apparently killed together, overcome by some common power” (ibid, p. 170).
Sudden and Unnatural Death
The muck pits of Alaska are filled with evidence of universal and catastrophic death. These animals simply did not perish by any ordinary means. Multiple thousands of animals in their prime were obliterated.
“We have gained from the muck pits of the Yukon Valley a picture of QUICK EXTINCTION.
Mining techniques used to unearth polar dinosaur
http://www.alaskajournal.com/stories/092307/hom_20070923011.shtml
:’)
Thanks. Santasaurus? ;’)
If you give a complete enough review maybe I won't have to buy it ;^)
;’) Buy it. The authors do a very good job explaining and relating everything; they’ve also concentrated on the Clovis event, but suggest further lines of their own research because of the evidence for the various waves of material from the supernova (the Clovis event was just the most recent).
Anyway, an item of curiousity for me is the apparent nastiness visited around Alaska at about the same time(I suspect other places will be discovered). Now, it seems catastrophic events are fairly rare and it would be quite the coincidence if our little planet were to experience two in a relatively short period of time. That is, a supernova's blast reaching us at roughly the same time as an impact from a comet/whatever. A single event is more likely -- whatever it was.
The evidence of gamma ray bombardment I gather is not in dispute? I don't know if it's been pointed out but I found THIS PIECE whilst looking for alternative sources for gamma rays:
...which discusses comet collisions as a viable source. Impacting our atmosphere might work the same way???BATSE requirements for a colliding comet source of gamma-ray bursts
- R. Stephen White
- Institute of Geophysics and Planetary Physics, University of California, Riverside, California 92521
The BATSE and Venera results place tight restrictions on possible sources of Gamma Ray Bursts, GRB. Collisions of magnetized comets in the solar system appear to satisfy the conditions of the observed isotropic direction distribution and the measured N(
Pmax) vs Pmax distributions where X is fluence, flux, maximum flux or ratio of count rate at maximum to the threshold count rate. The distances to the bursts (GRB comet cloud), and density of comets is tailored to the observed data. To satisfy observations of N(
I suppose the question is, if the P/H extinctions were caused by a single event, which is most likely?
Gotta run and see about actually getting some work done ;^)
it seems catastrophic events are fairly rare and it would be quite the coincidence if our little planet were to experience two in a relatively short period of time. That is, a supernova's blast reaching us at roughly the same time as an impact from a comet/whatever. A single event is more likely -- whatever it was.I wholeheartedly agree. The comet was also debris from the explosion, either directly or indirectly; either the comet made the whole trip, or was pushed by the actual debris into the inner Solar System.
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