Chris L Peterson wrote:
On Tue, 2 Sep 2008 10:17:31 -0700 (PDT), LarryG
wrote:

For the past week or so, I have been reading "The Cycle of Cosmic
Catastrophes: How a Stone-Age Comet Changed the Course of World
Culture" - by Richard Firestone, Allen West, Simon Warwick-Smith. The
authors attribute the extinction of the wooly mammoth, and other north
american megafauna, and the paleo-american Clovis culture, to a
probable comet strike at what is now Lake Michigan...

The science is generally poor. A few people claim to have found evidence
of a Holocene impact, but this is weak and not well supported.

It is my understanding that there is a widespread layer of magnetic
spherules marking the end of the Clovis period. That seems to me to be
somewhat more than "weak and not well supported." I know that there is
no evidence for an impact crater, but there was a thick ice sheet at the
time. The idea that the impact was on the ice seems reasonable, at
least at first glance. Has anyone done any modeling of this sort of
impact? Are you aware of a simpler alternative explanations for the
magnetic spherules?

Greg

P.S. I have not read the book yet. So if anyone out there is feeling
particularly insecure in themselves today, feel free to attack me for
that now. I take on all comers! ;-)

--
Greg Crinklaw
Astronomical Software Developer
Cloudcroft, New Mexico, USA (33N, 106W, 2700m)

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