Hi, EP, List,
It's this kind of wobble that makes so many people
dubious about the various and varying hypotheses
advanced by Firestone & Co. I put Firestone at the head
of the list because he has been the chief driving force
behind all this, to his credit.
Over twenty years ago, he uncovered evidence he
interpreted as a sign of an intense neutron event over
several states in the upper Midwest USA. The question
has always been: evidence of what?
Firestone is a physicist at Berkeley and a specialist
in isotopes, editor of the standard work on all the nearly
isotopes (8 editions), 130 publications, etc. He knows
what he knows; the evidence is real.
He is not an astronomer, a geologist, an anthropologist,
a climatologist, nor any of the other things needed to
answer the question: evidence of what? He has other
work to do, but he is the legal guardian of an orphan
fact.
When the evidence was restricted to a three-state
region, it was easier to explain. As it "spread" to a wider
continental basis and seemed to coincide with an "extinction,"
Firestone himself advanced completely silly explanations:
a comet formed from a supernova cloud blasted out at a
fraction of lightspeed hit the Earth, driving particles into
the bones of the mammoths, etc. etc. It was pitiful.
A really lousy hypothesis does not invalidate the
evidence. The Phlogiston Theory is crap, but there really
is such a thing as oxygen... Fire happens.
So, back when it was iron particles and supernovae,
I sent Firestone an email asking if he or anyone was searching
the particles for atoms of 60Fe, a iron isotope that is ONLY
produced in supernovae. He answered that it was a logical
thing to do but "was not easy." That is an understatement.
Knie, a German researcher, went through a (relatively)
huge amount of dated ocean sediments from the times of
a minor marine extinction 2.3 million years ago, using
a mass spectrometer. It took him 3 years. He found 23
ATOMS of 60Fe. You have to understand; he shouldn't
have found any. It can't be contamination; nobody keeps
a supernova handy in the lab. It was hailed for what it was,
a stupendously difficult achievement and an utterly
unexpected result.
Knie said innocently, well, we have to have been very
close to a supernova a few million years ago. Everybody
screeched in horror, so he shut up. Supernovae, as we
all know, leave a terrible mess behind, and there's none
of that. They're rare, they're scattered, we're safe,
absolutely safe -- go away, go away.
Well, now there's no mention of supernova iron particles
because of the new purely local asteroidal/comet hypothesis
advanced to fit the data. Firestone has gotten people to
help with it, and those people are impact-minded, the
paradigm du jour. I sneer and ask, "How does a comet
over North America explain the big spike in supernova-
produced 10Be in Antarctic ice cores at the same time?"
Firestone also found evidence of a similar event 34,000
years ago, and another 41,000 years ago, but mention of
that is gone from all the current foo-frah -- it's hard enough
to get folks to swallow one comet, much less two or three.
I had a link to his original data which showed the multiple
events, but -- guess what? -- it's a 404. But thanks to the
internet, nothing ever really goes away. Complete with nice graphs:
http://www.lbl.gov/Science-Articles/Archive/NSD-mammoth-extinction.html
Turns out we ARE closer to a whole bunch of supernovae
than we thought: a cluster of them, producing 20 supernovae
in 10 million years, that passed within 120 light years of us
only 2 million years ago (60Fe don't lie). Still, 120 light years
is a long, long way. It was considered a comfortable distance
until the 60Fe was discovered in conjunction with a minor
marine extinction. Something doesn't add up. Here's the
original paper on the Sco-Cen OB Association of stars by
Benitez and Maiz-Apellaniz:
http://xxx.lanl.gov/PS_cache/astro-ph/pdf/0201/0201018v2.pdf
and a simpler description here:
http://www.eurekalert.org/pub_releases/2002-01/jhu-asm010702.php
And here's a really complete discussion of this whole idea
of supernova effects on Earth, with good explanations of
the problems, and specifically those associated with the
Benitez and Maiz-Apellaniz proposal:
http://www.physicstoday.org/vol-55/iss-5/p19.html
Tracking the movements of stars through million of years
has possibilities of errors (in both directions), but all the worry
about being close to a supernova misses the point that the
debris from a supernova is a very considerable danger all
in itself. Those debris can travel, often at a high rate, typically
3% of the speed of light at the time of their formation, but
getting slower all the time (due to gravity).
Were we to pass through a dense dust globule of these
supernova debris, it could easily produce a disaster: loss of
all or part of the ozone layer, effects on, even temporary loss
of, the Earth's magnetic field, greatly enhanced radiation exposure,
sudden dimming of sunlight, abrupt climate shifts, a short nasty
and brutal ice age, all kinds of bad things -- it's a long list.
This why I'd like to get straightened out whether this
collection of evidence is under the mats or distributed through
it. The evidence itself could point to either event, but if it's
an impact, it should be under the mats, not scattered through
100, 500, or 1000 years of mat accumulation, whereas an infall
of dust accumulating in the mat could take place over a variously
prolonged time. Everything they claim to have found as proof
of the high pressure and temperature of an impact could be the
products of a much more energetic event: a supernova.
There was a long discussion of this on the List in Sept.-Oct
of 2005, with lots of back and forth. Probably still in the Archives.
There are a lot of dark (dust) globules in the Galaxy, all produced
by supernovae. We tend to dismiss them because we live in a
little dust-free zone called the Local Bubble which was, surprise!
created by a recent supernova that blew the then-existing dust out.
A lot like urban renewal... The moving globs represent a major
hazard nobody seems to worry about.
Yes, what we need: one more thing to worry about...
Sterling K. Webb
---------------------------------------------------------------------------
----- Original Message -----
From: "E.P. Grondine" <[EMAIL PROTECTED]>
To: <meteorite-list@meteoritecentral.com>
Sent: Tuesday, September 25, 2007 12:28 PM
Subject: [meteorite-list] Another news piece on Holocene Start impacts
Hi Sterling, list -
http://www.eurekalert.org/pub_releases/2007-09/nau-rts092407.php
This time the black mats are accumulators for the
impact debris.
I also want to remind everyone here that some of the
First peoples accounts of these impacts were given in
my own book "Man and Impact in the Americas". It is
nice to see field data confirm one's analysis of
traditions.
PS - while looking at spherules, I found that some of
the KT layers were nicely exposed and easy to sample.
I still think that there is going to be a market for
these impactite samples, but I how they will be
packaged is still not clear.
good hunting,
E.P. Grondine
Man and Impact in the Americas
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