The Chimera was Very Cranky that day!Phys.Org wrote:About 12,800 years ago when the Earth was warming and emerging from the last ice age, a dramatic and anomalous event occurred that abruptly reversed climatic conditions back to near-glacial state.
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This layer –– the Younger Dryas Boundary (YDB) layer –– also contains peak abundances of other exotic materials, including nanodiamonds and other unusual forms of carbon such as fullerenes, as well as melt-glass and iridium.
Bud Did It!
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Bud Did It!
Don't let other peoples limitations become your constraints!
My Deviant Art scribbles
The Atomic Guide to Basic GIMP Stuff
My Deviant Art scribbles
The Atomic Guide to Basic GIMP Stuff
Re: Bud Did It!
Can we still blame the extinction of megafauna on early humans, or is this another smoking gun?
Re: Bud Did It!
There's been a lot of controversy about the extinction of the megafauna. Overhunting by early (Clovis-culture) human immigrants has been one of the popular ideas... there have been plenty of other examples (e.g. Madagascar, Australia) which show that it can happen.
The suggestion that the Younger Dryas cooling, extinctions, and loss of the Clovis culture might be due to something like an asteroid impact or airburst has been around for some years. There's been some back-and-forth debate about it - some groups citing the presence of nanodiamonds and micro-tektites and pointing to the "black layer" as indications of continent-wide fires, other groups refuting these ideas. One paper from a couple of years ago asserts that many of the pieces of supporting evidence for an impact at that time simply don't add up.
This new study of the spherules is a very interesting one. The claim that the spherules were probably formed by rapid heating of local materials, rather than being volcanic in origin, is a good "push" in the direction of saying that something "big and hot" happened at that time.
As far as I can recall there's no known/recognized impact crater which dates to the initiation of the Younger Dryas cooling (hence, the suggestion that it may have been an airburst). A cometary body might have broken up into a whole shower of fragments which would spread out and then detonate separately, creating heat and blast damage over a very large area. A large asteroid skimming through the upper atmosphere might even have created the necessary heat and shock waves without actually detonating.
There have been suggestions that the Carolina bays might have been created by this sort of scattered impact or airburst at that time, but the physical evidence gathered so far doesn't seem to support that.
The suggestion that the Younger Dryas cooling, extinctions, and loss of the Clovis culture might be due to something like an asteroid impact or airburst has been around for some years. There's been some back-and-forth debate about it - some groups citing the presence of nanodiamonds and micro-tektites and pointing to the "black layer" as indications of continent-wide fires, other groups refuting these ideas. One paper from a couple of years ago asserts that many of the pieces of supporting evidence for an impact at that time simply don't add up.
This new study of the spherules is a very interesting one. The claim that the spherules were probably formed by rapid heating of local materials, rather than being volcanic in origin, is a good "push" in the direction of saying that something "big and hot" happened at that time.
As far as I can recall there's no known/recognized impact crater which dates to the initiation of the Younger Dryas cooling (hence, the suggestion that it may have been an airburst). A cometary body might have broken up into a whole shower of fragments which would spread out and then detonate separately, creating heat and blast damage over a very large area. A large asteroid skimming through the upper atmosphere might even have created the necessary heat and shock waves without actually detonating.
There have been suggestions that the Carolina bays might have been created by this sort of scattered impact or airburst at that time, but the physical evidence gathered so far doesn't seem to support that.