archiv~1.txt: SETI [ASTRO] Catastrophic Events & Mass Extinctions: Impacts And

SETI [ASTRO] Catastrophic Events & Mass Extinctions: Impacts And

Larry Klaes ( )
Mon, 29 Mar 1999 14:29:10 -0500

>X-Authentication-Warning: majordom set sender
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>Date: Mon, 29 Mar 1999 18:12:41 GMT
>From: Ron Baalke <>
>Subject: [ASTRO] Catastrophic Events & Mass Extinctions: Impacts And Beyond
>Reply-To: Ron Baalke <>
>Catastrophic Events & Mass Extinctions: Impacts And Beyond
>July 9-12, 2000
>Vienna, Austria
>This conference will be the fourth of an informal series of meetings on mass
>extinctions, global catastrophes, geological (and biological) implications
>of impact events, and related investigations, which were initially held at
>Snowbird, Utah, to discuss studies of the Cretaceous-Tertiary (K-T)
>boundary. The first and second of these meetings were held October 19-22,
>1981, and October 20-23, 1988. The third one took place February 9-12, 1994,
>in Houston, Texas. While the first two of these conferences had the K-T
>boundary as their main topic, and included vigorous debates on the evidence
>for an impact event 65 m.y. ago and alternative explanations, by 1994 this
>evidence was overwhelming due to the discovery and confirmation of the
>Chicxulub structure in Yucatan, Mexico, as the long-sought K-T boundary
>impact crater. Therefore, more recently the discussion shifted to the
>question if (and how) short-term, high-energy events influence the
>biological evolution on the Earth, and if the observed changes in the
>biological record show evidence of very short-term events other than the K-T
>boundary event.
>Current studies of the most profound extinction event in Earth's history, at
>the end of the Permian, indicated a much shorter time frame for this event
>than earlier data had suggested, with significant associated geochemical
>anomalies. The cause for this global catastrophe is currently unknown, but
>speculations center on massive volcanism or cometary impact. Other
>boundaries and short-term events (e.g., late Devonian, Triassic-Jurassic,
>late Eocene) in the stratigraphic record of the Earth are now receiving
>unprecedented attention. Thus, we feel that the time has come to summarize
>and discuss the current state of knowledge of the character and causes of
>mass extinctions and catastrophic events in the history of our planet.