Posted on 01/01/2009 2:09:17 PM PST by neverdem
Comet may have exploded over planet, causing fires, die-offs, researchers say
A meteorite colliding with the Earth 65 million years ago is considered to be the most likely reason dinosaurs vanished from the planet. Now a team of scientists says it has found new evidence that an object from space caused a similar extinction event only 13,000 years ago.
In an article to be published Friday in the journal Science, researchers present what one author calls the "smoking bullet"—proof that an exploding comet triggered the sudden, thousand-year freeze that killed off mammoths, saber-toothed tigers and other large mammals that used to live in North America.
Working at multiple sites across the continent, researchers found nanodiamonds—microscopic particles thought to be found on comets—in a 13,000-year-old layer of carbon-rich soil.
The authors, led by University of Oregon anthropologist Douglas Kennett, theorize that the comet exploded above the Earth's surface, raining fragments upon North America and starting fires across the continent. That would have ushered in an abrupt global cooling and caused the "megafauna" extinction.
In the layer with the nanodiamonds, fossils of the large mammals are abundant. After that layer, they disappear, said Allen West, an Arizona geophysicist and one of the paper's authors.
"It's extraordinary that tens of millions of animals disappeared synchronously at exactly the time when the diamonds and carbon layer are laid down across the continent," West said.
West said the event also would have affected human populations of the time. Artifacts from the Clovis culture of humans—an early hunter-gatherer society—also disappear after the 13,000-year layer, suggesting they, too, were killed off by the comet or its aftereffects.
Many archeologists remain skeptical of the comet theory, said Daniel Amick, an associate professor of anthropology at Loyola University Chicago who studies the Clovis culture.
"When most archeologists heard...,"
(Excerpt) Read more at chicagotribune.com ...
The longer first one, however, works just fine (as does this one)...
An English Mastiff, that's a big dog.
My dogs are doing just fine, thanks.
Evidence for an extraterrestrial impact 12,900 years ago
Proceedings of the National Academy of Sciences, October 9, 2007, Vol. 104
^ | Setember 27, 2007 | R. B. Firestone, et. al.
Posted on September 30, 2007 12:14:28 PM CDT by baynut
A carbon-rich black layer, dating to 12.9 ka, has been previously identified at 50 Clovis-age sites across North America and appears contemporaneous with the abrupt onset of Younger Dryas (YD) cooling. The in situ bones of extinct Pleistocene megafauna, along with Clovis tool assemblages, occur below this black layer but not within or above it. Causes for the extinctions, YD cooling, and termination of Clovis culture have long been controversial. In this paper, we provide evidence for an extraterrestrial (ET) impact event at 12.9 ka, which we hypothesize caused abrupt environmental changes that contributed to YD cooling, major ecological reorganization, broad-scale extinctions, and rapid human behavioral shifts at the end of the Clovis Period. Clovis-age sites in North American are overlain by a thin, discrete layer with varying peak abundances of (i)magnetic grains with iridium, (ii) magnetic microspherules, (iii) charcoal, (iv) soot, (v) carbon spherules, (vi) glass-like carbon containing nanodiamonds, and (vii) fullerenes with ET helium, all of which are evidence for an ET impact and associated biomass burning at 12.9 ka. This layer also extends throughout at least 15 Carolina Bays, which are unique, elliptical depressions, oriented to the northwest across the Atlantic Coastal Plain. We propose that one or more large, low-density ET objects exploded over northern North America, partially destabilizing the Laurentide Ice Sheet and triggering YD cooling. The shock wave, thermal pulse, and event-related environmental effects (e.g., extensive biomass burning and food limitations) contributed to end-Pleistocene megafaunal extinctions and adaptive shifts among PaleoAmericans in North America.
Peer-reviewed NAS paper -- not usually crackpot stuff...
I had actually stumbled across the abstract for that earlier, and was reading the full report when the phone rang!
http://www.pnas.org/content/104/41/16016.full
And the version coming out tomorrow is in Science.
BTW: I know two of the authors; not crackpots at all.
The book in post #37 is an excellent book.
bttt.
http://www.sciencenews.org/view/access/id/30552
A host of unusual geological features, collectively known as Carolina Bays, hints at the cataclysm's location, says team member George A. Howard, a wetland manager at Restoration Systems, an environmental-restoration firm in Raleigh, N.C. Around 1 million of these elliptical, sand-rimmed depressions, measuring between 50 meters and 11 kilometers across, scar the landscape from New Jersey to Florida. In samples taken from 15 of the features, Howard and his colleagues found iridium-rich magnetic grains and carbon spherules with tiny diamond fragments similar to those found at Clovis archaeological sites.
The long axes of the great majority of the Carolina Bays point toward locations near the Great Lakes and in Canada—a hint that the extraterrestrial object disintegrated over those locales, says Howard.e correlation between the Carolina Bays and this comet/asteroid event:
FWIW, I had no idea that there were nearly a million of those elongated crater features known as "Carolina Bays"...
He has a website with some maps, and the longitudinal features mapped out. (about a quarter of the way down the page).
Looks like two loci for two separate events.
http://www.georgehoward.net/cbays.htm
Oddly, I last week took a bit of a fascination with this stuff, stirred up a bit by Yellowstone.
Here's a better link for the excerpt in comment 69.
“it is not supported by fossil records.”
I strongly urge you to read Firestone’s book. It does a very good job of describing the careful scientific process by which the scientists who wrote the book collaborated in examining a number of different types of evidence from different sub-branches of science to develop the book. They also traveled thousands of miles to examine the evidence, all of which points to the idea that something terrible came out of the heavens 13,000 years ago, and triggered the Younger Dryas world wide cooling. It is well written for a non-technical but educated reader.
“Looks like two loci for two separate events.”
Actually, it looks as if there were 4 subevents in Canada, and 3 near Lake Michigan. Also if you go down further in the article there is a chart of temperature changes in Greenland. There you can see a profound and long dip that is the YOunger Dryas, but coming down from the temperature high around 15 thousand years ago (15KYA) there are three downward spikes that might represent less lethal events of the same type. So, given the 7 sub-loci, perhaps several occurred at each of these drops in temperature, until at the third one the Gulf Stream circulation was permanently disturbed for a thousand years.
Since bays overlap each other in several cases, if some can be found where the orientation is somewhat different, it might be very interesting to analyze material to determine if there was a different date for each.
Here is another interesting link about happenings in April 2008. Loud noises, earthquakes, lights in our mid-West, and in Argentina, with odd government explanations:
http://www.sott.net/articles/show/154007-Impact-Hazards-on-a-Populated-Earth-
My, my, my. A catastrophe 13,000 years ago? How novel.
It did to me, as well. As did the article posted a couple of weeks ago about the potential for a magnetic pole shift.
Yes, someone had posted a video that describes the earth crossing the galactic equator around or beginning in 2008. They associate crossing the galactic equator with a pole shift or magnetic disturbances, a debris field, etc.
Has George Bush been around that long?
From the mid-Atlantic rift zone records (5000 paleomagnetic earth scientists can't be wrong!), it would appear that the earth's magnetic field can die down within a scant 5000 years, and then start back up with reversed polarity. And the earth's magnetic field has decreased some 25% in the last 150 years since such measurements have been regularly taken.
I wouldn't worry about it, Obama has the answer, and Al Gore is his prophet.:)
Nope! Every time we look at the new president, we'll say, "Bush's fault!!!"
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