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From: kgd@rlvd.UUCP
Newsgroups: sci.bio,sci.astro
Subject: Re: Mass extinctions
Message-ID: <260@rlvd.UUCP>
Date: Sun, 12-Apr-87 01:22:16 EST
Article-I.D.: rlvd.260
Posted: Sun Apr 12 01:22:16 1987
Date-Received: Wed, 15-Apr-87 03:15:51 EST
References: <6760@alice.uUCp> <496@uokmax.UUCP>
Reply-To: kgd@rlvd.UUCP (Keith Dancey)
Organization: Rutherford Appleton Laboratory, Informatics Division, U.K.
Lines: 30
Xref: utgpu sci.bio:278 sci.astro:836

In article <496@uokmax.UUCP> david@uokmax.UUCP (David Lee Cox) writes:
>I really like this discussion, but am a little confused about a couple of
>things,  What would volcanoes, or meteors do that could cause mass extinctions?
>
If I may be brief, then atmospheric dust would be a candidate in both cases, in
the same sense that thermonuclear war is predicted to lead to the well-known
nuclear winter theory.
 
Another interesting theory that I have heard put forward by Dr Clube is the
possibility of meteor impact of sufficient momentum to reverse the rotation
of the Earth.  The molten core would continue to rotate as before, but the
solid crust would be knocked into temporary reverse.  Eventually, frictional
forces would capture and return the crust rotation to its original direction.
The proposed consequences of this being a temporary halt in the Earth's
magnetic field, followed by field reversal before, eventually, returning.  The
temporary influx of increased solar radiation being the cause of mass
extinctions and new mutations.
 
I am in no position to verify the efficacy of this hypothesis.  I have never
seen the figures for the meteor mass required to do such a thing, even
assuming an impact along the equatorial line in a direction opposite to
the Earth's rotation.  Any takers?
 
-- 
Keith Dancey,                                UUCP:   ..!mcvax!ukc!rlvd!kgd
Rutherford Appleton Laboratory,
Chilton, Didcot, Oxon  OX11 0QX             
                                            JANET:       K.DANCEY@uk.ac.rl
Tel: (0235) 21900   ext 5716