Re: extinctions

[Stan Friesen <swf@ElSegundoCA.ATTGIS.COM>]

>From: Ralph Chapman <MNHAD002@SIVM.SI.EDU>
 > Another school of thought would suggest that none of these mechanisms
 > in themselves is enough to produce a major global mass extinction - that
 > each produces more minor ones that we see (and sometimes not) in the record.
 > Instead, the mass extinctions may only occur when a group of different
 > mechanisms manage to happen within a critical threshold period of time
 > and major taxa by the buckets full just finally say the hell with it
 > and croak.

I am glad you mention this, since it is actually my position.

Thus, I am not denying that the K-T impact(s) contributed to the
extinction, only that it was the *sole* cause.

In the case of the K-T extinctions I think the combination of the
extreme marine regression, the Deccan volcanism, and the K-T impact
caused the extinctions.

For the Permo-Triassic extinctions, it was a combination of reduced
provinciality, the Siberian Trap volcanism, the glaciation, and
probably a period of oceanic anoxia that caused the extinctions.
 

swf@elsegundoca.attgis.com              sarima@netcom.com

The peace of God be with you.