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Forgive
me if I'm repeating something already covered on this list, but in case it has
not been referenced, for those of you
interested in examining continuing evidence that the Cretaceous-Tertiary
extinction event was the result of the impact of a cosmic (extra-terrestrial)
body or bodies, instead of being due to volcanic activity such as the Deccan
traps, new evidence is reported by A. Shukolyukov and G.W. Lugmair in SCIENCE,
Vol. 282, pages 927 through 929, October 30, 1998.
The
authors report that high-precision mass spectrometric analysis of chromium in
sediment samples from the K - T boundary, to quote, "...coincident with the
extinction of numerous organisms on Earth...", from Stevns Klint, Denmark,
and from Caravaca, Spain, "...is different from that of Earth and indicates
its extra-terrestrial source".
We are
told that, "...the chromium isotopic
signature is consistent with a carbonaceous chondrite-type
impactor."
The quotes herewith are from the
abstract, page 927.
If any
listers wish to discuss this matter on the list, please take time to read the
referenced article FIRST, as the evidence is carefully described and discussed
therein. Accordingly, please address the report's contents and not
my reporting of it. If you're anti impact-extinction, please don't try to
shoot the messenger, as I'm only passing along something that could be of
interest. SCIENCE's web site is www.sciencemag.org.
For
those of you who may not be very familiar with meteorites, carbonaceous
chondrite impactors (meteorites) have been compared to the very dark, evidently
carbonaceous asteroids that tend to range farthest out (relative to earth's
orbit), but indisputable aqueous alteration within some carbonaceous chondrites
(meteorites) strongly suggests melt conditions such as are encountered at and
near perihelion by comets.
Food for
thought, "Was earth -- in the K - T event-- struck by a comet or cometary
debris similar to what happened to Jupiter recently, but not on such a grand
scale?" I know, that's not a new idea.
Thanks
for listening,
Ray
Stanford
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