Re: Extinction

[psparks@CERF.NET (paul sparks)]

Hi folks!

I guess I need to get into the argument for what its worth.  Based on the
modelling that was done wrt the nuclear winter scenario and then wrt to
bollide hits it seems pretty obvious to another physist anyhow (we all may
be somewhat daft) that at least the entire north american fauna would be
severely effected to the extent that the major players would be wiped out.
It does not need any of the sulphur coincedences to accomplish this. From
the arguments of the statistics people that in itsself would not leave a
peak, but it would seem to leave an absense.  There is the possibility that
the north american fauna could be replaced over a couple million years and
that should show up as a different ensemble of animals and that should be
observable. 

So I guess that I would have to agree that if there is such an impact then
there should be a fossil record to support it and since there appears to be
none other than the KT extinction then that must be it. One can certainly
disagree that the effect of an impact is less than I believe but I really
think that most of that part of the story has been readily modelled.

Oh I did have a question out of all of this.  I thought that previous
threads had pretty well decided that the Decca events were in fact
temporally differentiated from the KT booundary.  I ask this because a
friend and I had done some back of the envelope stuff and had decided that
it might be possible that a 100 mile bollide could have "set off" the Decca
lava flows.   It seems that just about enough energy could have gotten
there.  But we decided that this forums discussions had firmly separated
these events.  Whatever.

And then Mickey Rowe kicked in with the slow die off fossil record thing.
I'm a bit confused but I thought that I read in Science a couple years ago
that there was a definitive study done that in fact showed the opposite when
one looks at all the record.  In addition the statistics tah I memtioned
knocked off the argument that there should be a spike.  One of the problems
I have is that I don't know who to believe even within a given discipline.
Who keeps a running account of the different arguments and worth of such
studies? How can a paleotology amature like me susposed to make useful
conclusions if all statement s seem to be autocratic in nature? Hmmmmmm

I get the same feeling when I read Tom H's comments in thaty he "states"
things as truth that from the litereature that I have read (Science, some
physics things and popular stuff like scientif american) don't seem to be
the last arguments on the subject.  Is this a discipline thing?  Do we have
a fossil types versus some other group?  I don't know, but I am surprised by
the arguments that I've heard and especially the Facts that have been
stated.  I'm probably just getting old.  sigh.................



>Again, sir, your argument is specious.  The Siberian explosion (that's
>Tunguska explosion, by the way) was from an object that was at most 100 feet
>in diameter, where the object responsible for the Mexican crater was probably
>well over 10 miles across.  Giving you the most generous of measurements the
>Mexican object had more than 150,000,000 times more mass.  It is highly
>unlikely that a comet or anything else that large would have simply exploded
>into nothing and leave no crater.  The object may well have been a comet, but
>it need not be.  Any object of this size, sir, be it comet or asteroid could
>easily be ripped apart by tidal forces.  Indeed our moon itself would be
>ripped apart by Earth's gravity if it were close enough.
>
>By the way, there is recent evidence of another, smaller impact crater in the
>Pacific that is being claimed as a secondary impact.
>
>Oh, and the Shoemaker-Levy comet demonstated exactly the opposite behavior
>you suggest.  The impacts made with Jupiter were much more energetic than
>almost anyone predicted, thus strongly suggesting that large cometary
>fragments maintained their integrity.  Most of the break-up you mention
>occurred due to tidal forces far, far outside of Jupiter's atmosphere and it
>is similar to what probably happened 65 million years ago on earth.
>
>V. S.
>
>
paul w. sparks  Psparks@cerfnet.com
"over the heather the wet wind blows
I've lice in my tunic and a cold in my nose."
anon