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Re: extinction

Response to Phil Bigelow's Thu, 08 Jan 2004 12:53:07 post (below the dashed line).

Dear Phil, your suggestion on use of falsification (albeit on stratigraphy) in K-T science really struck close to home.

The K-T impact versus volcanism debate began at the May 1981 K-TEC II meeting in Ottawa, Canada, when I first encountered the Alvarez impact team. At that time, the K-T iridium was the sole basis for a K-T impact event.

At that meeting, I discussed how the Deccan Traps volcanism might have released the K-T iridium onto earth's surface. I had already made the connection between the Deccan Traps volcanism, a K-T carbon cycle perturbation, the mass extinctions, and the K-T iridium, at the January 1981 AAAS national meeting in Toronto.

My work caught Luis Alvarez by surprise. When I equivocated the basis of his impact theory by suggesting a source for the iridium other than impact, he became terribly upset with me. A word-by-word transcription of our public exchange can be found in the K-TEC II Proceedings volume, "Cretaceous-Tertiary Extinctions and Possible Terrestrial and Extraterrestrial Causes," Syllogeus, No. 39, 1982.

To make a long story short, I felt that for Alvarez to continue his claim that the K-T iridium was "proof" that an impact event had triggered the K-T extinctions, he would have to falsify my argument that the Deccan Traps might have been the source of the iridium.

Dewey McLean


Before the multiple impact hypothesis is widely accepted, the
single-impact/redepostion hypothesis should first be falsified.  This
would involve studying the *micro*stratigraphy of K-T outcrops where the
layer(s) are well-defined, looking for evidence of current-imposed
micro-structures and textures.  Obviously, this is more along the lines
of Masters- or PhD-level work.