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Re: Extinction

In <950419223958_89319402@aol.com> VanKathy@aol.com writes:
>I am very familiar with the scientific process and informed inquiry and
>scepticism are at its heart, but there comes a point beyond which it becomes
>less a rational pursuit and more of an emotional, personal, and sightless
>flight from reason.

>Few scientists spend their time trying to disprove the theories of
>relativity, Maxwell's equations, evolution (excluding those driven by
>religious reasons), etc. For some theories the time comes where the theory
>becomes accepted as fact.  The impact theory is one that rightly belongs in
>this class.
>I hate to see good science break down into irrational and sometimes childish
>bickering and chest thumping.  The arguments still being made against the
>impact theory are not shining badges of the scientific method, but ugly
>stains that are beginning to cost science face.
>Van Smith


Don't be too hard on people who are reluctant to accept the idea of
impacts causing great catastrophic changes on Earth. As late as 1970,
there were still a few geology profs who refused to teach plate
tectonics and were still relying on the old geosynclinal theory with
its associated continental accretion.

As more and more evidence accumulates that a variety of catastrophic
events have profoundly affected Earth's history, people will become
more receptive to the idea of a bolide impact ending the Cretaceous.

Whether a bolide impact occurred at the K/T boundary is one question;
whether such an impact caused any extinctions (of dinosaurs or other
groups) is another, and one that is much more difficult to address.
I agree with you: a massive impact occurring at the same time as
widespread extinction does seem like more than coincidence. Allow
the paleontologists an opportunity to reach this conclusion on their
own, using the tools they know best. But don't be surprised if some
paleontologists never accept the relevance of a bolide impact to 
K/T extinctions.

You may want to take a look at the following book:

   Meteorite craters and impact structures of the Earth
   Paul Hodge
   Cambridge University Press, 1994
   124 p.

He describes 24 such structures in the U.S., 26 in Canada, 8 in
Latin America, 19 in Australia, 34 in Europe, 12 in Africa, and
18 in Asia. The book is well illustrated and very interesting.


*Larry S. Bowlds        lbowlds@geosociety.org
*Geological Society of America
*Bulletin Managing Editor
*(303) 447-2020, ext. 147