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Re: craters and the k/t (Norm King)



In a message dated 96-08-22 04:37:08 EDT, you write:

<SNIP>


> Scientific theories should be 
>  regarded as conclusions in civil proceedings--the issue is decided on the 
>  _preponderance_ of the evidence, rather than _beyond any doubt_.  So, 
>  while Chicxulub has not been unequivacally proved to be an impact crater 
>  of a meteorite, that explanation is clearly supported at this time better 
>  than any alternatives.  But, hey, let's invite the critics to keep trying 
>  to poke holes in the hypothesis.
>  

I wholeheartedly concur with Norm's assessment of the K-T debate. I just
would like to add that even among the K-T skeptics, many have come around to
accept the Chcxulub structure to be of impact origin. Now the debate has
shifted to it's actual physical dimensions. Some argue for a lower bound of
~100Km and argue that such a small impact was not sufficient to cause the K-T
extinctions. Others argue for an upper bound of nearly 300 Km; more than
enough to cause a catastrophe. Then there are those who argue that the crater
is _older_ (i.e. early Maastrichtian or Late Campanian in age) and is
therefore not temporally related to the extinctions. Still others accept the
impact per se and argue that there was no mass extinction and a few holdouts
are skeptical period!
Until the skeptics punch enough holes in the theory to sink it, my bet is
with the impact . With all due respect !

Regards,
Thomas R. Lipka
Paleontological/Geological Studies