[meteorite-list] new KT impact hypothesis

From: E.P. Grondine <epgrondine_at_meteoritecentral.com>
Date: Fri, 7 Sep 2007 09:04:07 -0700 (PDT)
Message-ID: <921600.67020.qm_at_web36910.mail.mud.yahoo.com>

Hi Sterling -

Let me start by saying thanks much for your commentary
on this.

Oh Boy! Great new theory - instead of having to try
and find bits of "stuff" from space as black as coal,
the NEO search teams now have to find bits of "stuff"
from space as black as coal.

I remain skeptical. Does anyone have any samples
showing carbonaceous fused with an L6? Are there any
meteorites evidencing in any way the initial impact of
this new hypothesis? It seems to me there should be
plenty of them, whether they were understood that way
originally or not. Call it the mercenary in me, but if
there are, then some peoples' collections will take a
big jump in value.

The crater counts are still pretty bad - generally the
planets surfaces are dated by them using the estimated
flux, so the "data" on flux and ages is pretty bad.
Further, none of the flus models agree across all
planets. Furthermore, the one place where absolute
work on this can easily be done, the Earth, has not
been examined in adequate detail.

Crater size is linked to impact energy, and there's
two components to this: speed and size. Pathetically,
too few of the larger craters here on Earth have been
examined to determine what has hit. My guess is that
the larger ones are all cometary, based on energy, but
with this new theory one has to have firm estimates of
the mass of the impactor in hand for that assertion.
(Brenham was not that big of a hole; Sudbury was, and
was an iron.)

The only firm item in this debate is the 26 million
year chaotic cyclical extinction map here on Earth,
and until NASA spends some decent money examining
other planets in terms of Clube and Napier's injection
mechanism (their 26 million year cycle should be
showing up elsewhere), then excuse me if I remain
skeptical of the latest hypothesis.

E.P. Grondine
Man and Impact in the Americas















       
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Received on Fri 07 Sep 2007 12:04:07 PM PDT