Saturday, January 03, 2009

Killer Comet Theory Crosses Important Threshold!

I've written a number of times re the theory, proposed by scientists like Allen West and others, that

Well, the theory achieved an important milestone in the last couple of days: a peer-reviewed paper on the topic has come out in the highly regarded journal Science, and the authors have been kind enough to make the .pdf available here. Specifically, the multi-institutional team behind the paper have discovered

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.

Tiny diamonds, in other words, of the kind that tend to be associated with ET impacts.

Now, the theory is still a long way from proven. As one of the paper's referee's has noted:

Several objections have been lodged against the hypothesis. For one thing, it is not entirely clear that the Clovis Culture collapsed at the appropriate moment. One recent paper found no evidence of a population decline among the Paleoindians at 12,900 ± 100 calBP .

Another issue is the lack of a crater:

I actually raised this point in an earlier post on the topic. Dr. West's response, which obviously Mr. Koeberl has heard and thus far found unconvincing, can be found here.

Incidentally, Dr. West's description of the event

...seems to call into question of the more intriguing recent findings that, as of last year at least, was cited in favor of the hypothesis: the mammoth corpses that appear to have been pelted with microscopic with iron fragments. It was argued that these fragments were bits shed from the impacting object. If so, however, should these mammoth corpses not have been "seriously burned" or perhaps even disintegrated?

Meanwhile, special exploding bonus: did a meteorite trigger a tsunami off New York City?


Anonymous said...

Features known as Carolina bays are also purported to be a result of the event:

Anonymous said...
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Anonymous said...

Not sure if you caught this very interesting paper big lib, make sure to see the photos of the black mat in the supporting material: