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Re: impact



Kimba4evr@aol.com wrote:
> 
> Amatuer here with 2 questions -
> 
> First I believe I heard on a Discovery show that there is evidence for large
> impacts at each of the major extinction events - did I hear this correctly?

Well, at least one of the major extinctions...the K-T rxtinction.  There
might be other impacts associated with other extinctions, but I don't
know if they are confirmed or not.  And for the largest extinction, the
one dividing the Permian from the Triassic, there is no impact structure
known that I am aware of.  There is a danger of using impacts as
cure-alls for extinction events.  Impacts certainly effect at least
local environments, and to a degree global ones, but it is not yet known
if such impacts could truly cause widespread, massive extinctions,
despite the horrific after effects.
> 
> Secondly - my studies of the K-T Event indicate firestorm and the impact
> causing increased volcanic activity.  OK so everything near impact would have
> been totally incinerated but further out firestorm would have killed, even
> burnt off all flesh but not completely cremated remains, without survivors to
> predate carcasses or crush them and increased volcanic activity to quickly
> bury these remains shouldn't we find at least a few fossils showing burning?
> Has anyone found any fossils that appear to have been severly burnt?

Being an amateur myself, I'm also a little fuzzy on this one.  Would
massive fires leave evidence in the fossil record?  In the end, I
suppose it comes down to whether or not a fire damaged skeleton is in
the right place at the right time for fossilization.

There was a report that a school of fossilized fish was found (location
I do not recall...this was in Discover magazine some months ago, I
believe), dating from the time of the KT Impact, and that the sediments
indicated buriel by material displaced by the impact.  That may be as
close as we get.

I would assume that fire damaged fossils are relatively rare in any
case.  After all, I'm sure that forest fires and such have occured
throughout the earth's history, yet there are no remains of animals that
I know of that have been found in association with them.  Besides, bones
are quite combustable.  I think that if an animal was exposed to flame
intense enough to burn away flesh, its bones would follow suite.

Oh yes, about volcanism...as far as I know, the Deccan Traps in India
was the site of massive...and I mean Biblically massive...volcanic
activity.  Now, as to whether or not this was caused by the impact, or
just so happened to be occuring at the time of the impact but was
unrelated to it, I can't tell you, and I don't know if anyone really
knows for certain.  But that activity certainly had an impact on the
environment as well.

Regards...

-- 
John M. Dollan
Montana State University-Northern
Graduate Assistant
http://www.geocities.com/Athens/Academy/1861/
ICQ# 308260

"To make an apple pie from scratch, you must first create the
universe...."  Carl Sagan