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Re: Theories on the extinction of dinosaurs



At 08:59 PM 11/15/99 -0500, Dinogeorge@aol.com wrote:
>In a message dated 11/15/99 8:29:36 PM EST, sarima@ix.netcom.com writes:
>
><< That wasn't the point.  The point was that for most terrestrial vertebrate
> sites, the resolution of the putative K-T boundary temporally is not
> sufficiently precise to allow confidence about any simultaneity or lack
> thereof around the world. >>
>
>Wherever the resolution is good enough, the K-T boundary clay gets the same 
>date. I think there are now several dozen sites where this is true, though 
>most are not terrestrial.

Yes, the layer, if there is only one, gives a precise date.  Unfortunately
it is not found in the majority of terrestrial vertebrate sites, so other
means must be used to place the K-T boundary.  (It is even absent from many
*marine* sequences, where there are disconformities at the boundary).

[Note: in some sequences there appear to be multiple iridium enhanced
layers near the K-T boundary, so there is some slight suggestion of
multiple impacts over many millenia].

--------------
May the peace of God be with you.         sarima@ix.netcom.com