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Re: Isotopic Evidence for the K - T Impactor and Its Type

At 12:51 PM 11/10/98 -0500, RAY D STANFORD wrote: 
    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".
Actually, this doesn't address my remaining issues with the simple impact
scenario.  I do *not* deny an impact happened at that time.  Thus evidence
that the impact occurred does not in any way change my views.

My doubts come from two areas:

1. Questions about the simultaneity of the extinctions.  If the extinctions
occurred over a measurable span of time, they could not be caused by any
single discrete event, or even a short series of events within a few years
of one another.  Some of the issues regarding the timing of the extinctions
have not yet been addressed to my satisfaction.

2. Questions about the sufficiency of an impact, short of a planet busting
one, to cause such extinctions.  Given that similar impacts appear to have
occurred at other times, times for which no major extinctions are known, I
find it hard to accept a simple impact as the *sole* cause of the extinction.

Thus, I need two sorts of articles: ones that address the *timing* of the
extinctions, especially ones that address the issues brought up by the
results of studies using a method called graphical correlation; and ones
that address mechanisms that make this particular impact more effective
than other, otherwise similar, ones.

May the peace of God be with you.         sarima@ix.netcom.com