The Last Extinction What Caused It?
by frankiespeakin 19 Replies latest jw friends
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Kudra
This "latest extinction" is not referring to the dinosaurs or the "global flood". It refers to the extinction of the megafauna that populated the northern hemisphere at the end of the Pleistocene epoch (this happened about 12,000 - 13,000 years ago).
There are the climate change folks, there are the over-kill folks and now there are the asteroid-impact folks.
The asteroid impact has been a big splash in the extinction literature lately but it is really just a big flash-in-the-pan... (yuk yuk)
In all likelihood it is a combination of rapid climate change coupled with the introduction of humans in the new world.
Initial studies that pointed to evidence of an asteroid impact with subsequent widespread fires all over the northern hemisphere have been found to be severely lacking.
The whole "controversy" was very interesting.
We had a neat event at our university called the "Scopes Mammoth Trial" where we weighed the evidence for and against the asteroid impact theory. Three or four of the original scientists that discovered the stratigraphic layer that is claimed to house the evidence for the asteroid impact were present. They all gave the asteroid impact theory a big "ppphhhlllbtbtbt!" and a thumbs down.
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frankiespeakin
Kudra,
How do u feel about the nanodiamonds in high concentrations captured in the glaciers layer for that time line.
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Kudra
Hi Frankie
The supposedly high nanodiamond concentration that is said to be in the layer associated with the Younger Dryas "asteroid impact" was reported by one study- it is not generally accepted as representing actual nanodiamonds and has not been replicated by any other study.
A study done using the same stratigraphic layer as the original study PLUS seven other sites that have the same stratigraphic layer has not shown any high nanodiamond or "magnetic microspherule" concentrations.
A funny anecdote: one of the professors present at the "Scopes Mammoth Trial" said he went and swept off the top of his roof and found more nanodiamonds and microspherules in that dust pile than were reported in the original study!! ...it sounds like an "off-the-cuff experiment" on his part, but he actually carried out a very controlled sampling process on said roof...
Other comments about the nanodiamond layer that was originally sampled: this layer represents a surface that was exposed for thousands of years. that is a long time for a surface to remain uncovered by other sediments. This long residence time at the earth's surface could also contribute to the high number of "nanodiamonds" that were found there.
Also, another study is currently ongoing where the radiocarbon dates of occupations that span the time period before, during and after the Younger Dryas "impact" are being cataloged. The purpose of this is to see if there is any shift in number of human dwellings (frequency of sites or gap in the ages of sites) at the time of the "impact". So far (and I have only seen preliminary graphs of this) there is no perturbance in the number or frequency or timing of human dwellings as you go across this temporal boundary. If there was an asteroid impact that caused widespread fires and extinctions there would be a slight (at least) decrease in the number of archeological sites.
-K
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White Dove
The spotted owl in the northwest almost was the last extinction. I hear that wolves are now on the menu.
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Kudra
Frankie- I have papers on both the original study and the reevaluation of the original study if you would like to see them. The papers are actually relatively easy to wade through :)
I can email them to you if you would like- the journal doesn't allow you to access them directly unless you are a student at a university (or pay $$$ to the journal).
-K
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Kudra
Hey Frankie-
I sent you the papers :)
Outlaw-- that's just wacky n bizarre!!
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frankiespeakin
Thanks Kud
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Outaservice
I think they believe the Dinosaurs were smoking!
Outaservice
