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Re: Permian extinction



I haven't said anything for a while, so here is my random thought for 
the day....

 >.......  tis seems to depict a 75%
> chance of the P-T impact site not ever being discovered due to its slightly
> more likely chance to have struck in the vast Permian ocean. No?
> ..........PS, it might make for an interesting study to see if possible
> impact sites line up with large scale extinctions in gereral in a 1:4 ratio.
> 
> 
If the impact was in the ocean, and as the ocean lacked much 
continental shelf at the time, then I wouldn't have thought that a 
slight increase in moisture in the atmosphere would have caused an 
extinction.  The importance of the continental shelf is that if the 
bolide hits the ocean over the shallow sea, there is a possibility 
that it will throw a lot of fine particles, and perhaps burning hot 
too, into the atmosphere.  If it was a bolide 
(meteorite/asteroid/comet) that caused the Permian extinction, I 
would have expected it to have impacted off the eastern coast of the 
continent or somewhere on land.  This makes it more likely to be 
discovered at some time assuming the impact site has not been 
subducted below a continent.  For the Permian extinction, I don't 
think it is necessary to invoke an extra-terrestrial cause.  Fauna 
and flora were very restricted anyway due to the lack of the 
continental shelf and massive arid continent.

Neil
Neil 'Jurassic' Clark
Hunterian Museum
email: dinosaur@museum.gla.ac.uk