[meteorite-list] ARCTIC IRONS, was Mammoth Stew, etc

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Mon, 24 Dec 2007 18:46:07 -0600
Message-ID: <06ff01c8468f$89fcc190$b64fe146_at_ATARIENGINE>

Hi, Jason, List,

> I would dispute this claim [NWA depletion]
> ... irons compose ~1.8 percent of finds...

    NWA iron finds are 0.2% in contrast to Antarctica's
1.8%. Sounds "depleted" (89% depletion) to me. That
the Antarctic iron find percentage is "typical" of the planet
is not so absolutely clear cut. Take your pick:

"First, the very strongest meteorite type, metallic iron,
makes up only about 3 percent of the falls, but at least
30 percent of the finds..." -- John S. Lewis, UofAZ
http://books.google.com/books?id=k9hwi3ktye8C&pg=PA88&lpg=PA88&dq=meteorite+irons+percent+of+finds&source=web&ots=ph81fSImWj&sig=I4xsgM6wBgZ5sgXhOn34Tbi15h0

http://www.amsmeteors.org/fireball/faqf.html
says 2% of falls and 28% of finds...

http://earthsci.org/fossils/space/craters/met/met.html
"5.7 percent of meteorite falls are irons."

http://wapi.isu.edu/geo_pgt/Mod05_Meteorites_Ast/mod5.htm
"only about 3 percent of all observed falls are irons"

http://www.niger-meteorite-recon.de/en/story4.htm
"The ratio of iron meteorites compared with the
total number of falls is around 4 percent. As a
matter of fact the fraction of irons compared to
the total number of meteorites recovered from the
African deserts is only 0.2 percent. Until today
the enigmatic missing of the desert irons is an
unsolved question. Provided that the pre-Islamic
inhabitants of the Sahara, like their northern European
contemporaries, collected and traded meteoritic
iron as a raw material over longer periods then
one has an indication for the loss of these irons.
For in the region of the Air Mountains the first
iron arrow- and harpoon points are documented
as early as 2,400 B.C.. Thus there is a period of
more than 4,000 years until today in which the
early nomads could have harvested the meteoritic
iron from its deposits."


The American Meteor Society FAQ, posted on
http://abob.libs.uga.edu/bobk/ccc/cc062398.html
by Ron Baalke:
"Meteoroids of asteroid origin make up only a small
percentage (about 5%) of the overall meteoroid
population, which is primarily cometary in nature."
Note that this is "meteoroid," not "meteorite."

http://books.google.com/books?id=DIppUb33M8UC&pg=PA23&lpg=PA23&dq=meteorite+irons+percent+of+finds&source=web&ots=qIif2Elw5U&sig=wd3x_-gSl6QYgrDyDTZIsTAFekg#PPA24,M1
claims the percentage of iron finds is greater
in the Western Hemisphere. E. J. Opik's
"Physics of Meteor Flight in the Atmosphere."
Tennesse is a good example of the phenomenon.


Since we know that irons are preferrentially removed
by man over historic time periods, it is hard to explain
any percentage higher than Antarctica's "pristine" and
ungathered 1.8%. Preferential removal should LOWER
the percentage, not raise it.

    It may be that irons are harder to spot in Antarctic
glaciated "Blue Ice" environments than stones, or it may
be that since all Antarctic meteorites are discovered as
a result of a complicated ice-flow and wind-esposure
transport interaction that the more dense irons do not
"transport" as well, or it may be that Antarctica is
"depleted" in irons for some reason no one's thought
of yet.


Sterling K. Webb
--------------------------------------------------------------------
----- Original Message -----
From: "Jason Utas" <meteoritekid at gmail.com>
To: "Meteorite-list" <meteorite-list at meteoritecentral.com>
Sent: Monday, December 24, 2007 5:41 PM
Subject: Re: [meteorite-list] ARCTIC IRONS, was Mammoth Stew, etc


Hola All,

Sterling, you said:

>The distribution (or relative absence) of irons in NWA material shows
that there is no doubt that the NWA area was "cleaned out" of most of
the iron meteorites that could be found thousands of years ago. Of
course, they missed a few. But if the NWA meteorites reflected the
"normal" distribution of irons and stones, there would be many, many
more irons.

Based on Antarctic findings, which are supposedly unbiased, I would
dispute this claim. In the Antarctic, irons compose ~1.8 percent of
finds, and I see no reason for this to be an incorrect representation
of fall statistics.
When looking at fall statistics, one must keep in mind that an iron
would still be more recognizable than a stone, and as such, would be
more likely to be picked up.
Thus, even fall statistics are undoubtedly biased towards irons,
whereas Antarctic find statistics should be rather more correct,
rendering this 'Saharan clearing of irons,' although possible, much
less influential with regard to their percentage of total finds.

Regards,
Jason

On Dec 24, 2007 3:12 PM, Sterling K. Webb <sterling_k_webb at sbcglobal.net>
wrote:
> Hi, All,
>
> You couldn't ask for a less likely place to search for iron
> meteorites than the Canadian Arctic. First, a great deal of
> Canadian Arctic surficial material was "pushed" far south by
> those glaciers; there's a nice "car-eating" three-ton chunk of
> Canada on the road about a quarter-mile from my house (Illinois).
> Then, there's Bigger-Than-Biblical Floods at the end of glaciations,
> which would disperse the material remains (meteorites) of an
> impact. Then, there's those Jack-Daw Humans, picking them
> all up and using the iron for tools!
>
> About four years ago I posted to the List a reference to a paper
> by a group of archaeologists at one of Canada's national museums
> (which now I can't find, of course), documenting the distribution of
> pre-Columbian iron artifacts all across the ancient Eastern Arctic.
> Analysis of the material used showed that most, but not all of them
> came from the great Greenland irons (Cape York). Almost found it:
> short report full of other referrences here:
> http://adsabs.harvard.edu/full/1988Metic..23R.288M
>
> The age of the sites shows that the Greenland irons were being
> used for tools as early as 1300-1200 BC and the tools from it were
> spread out over 800 miles away from Cape York! Curiously,
> this makes the Neolithic North's iron tools pretty much the same
> age as first iron "tools" (weapons) in the "Cradle of Civilization"
> (the Hittites), which raises some interesting questions about the
> meaning of progress, innovation, and that "civilization" thing...
>
> Clearly, if iron meteorites from an ancient impact covered that
> portion of Canada, they would have been used also. If an ancient
> (33,000 BP) iron impactor had struck the ice cap and was the same
> compositional type as Cape York, they could be in that material,
> One of eleven ancient tools recently analyzed was from a different
> meteorite than Cape York, so we know there was another source in
> the extreme East Canadian Arctic (not Disko Island telluric iron
> either).
>
> The terrestrial age of Cape York is not known. Buchwald only
> says it is at least 2,000 years, but could be "10,000's of years."
> We tend not to think of the giant Cape Yorks as mere cast-off
> fragments of a bigger impact object, but they could be, of course.
> If the giant meteorites were being used for tool material, obviously
> all smaller pieces of the same material would have been used first,
> before undertaking the effort of beating chunks off the giants. Not
> an easy task.
>
> The distribution (or relative absence) of irons in NWA material
> shows that there is no doubt that the NWA area was "cleaned out"
> of most of the iron meteorites that could be found thousands of years
> ago. Of course, they missed a few. But if the NWA meteorites
> reflected the "normal" distribution of irons and stones, there would
> be many, many more irons.
>
> Finding any Arctic Canada iron meteorites may be impossible,
> if you consider that thousands of years of gathering by sharp-eyed
> locals intimately familiar with the region may have worked the ground
> first!
>
>
> Sterling K. Webb
> -------------------------------------------------------------------
> ----- Original Message -----
> From: "E.P. Grondine" <epgrondine at yahoo.com>
> To: <meteorite-list at meteoritecentral.com>
> Sent: Monday, December 24, 2007 12:32 PM
> Subject: Re: [meteorite-list] Mammoth Stew, Jason stops
>
>
> Hi Jason, all -
>
> Glad to hear you're done. That makes for a Merry
> Christmas indeed! I and others will be working on
> possible neutron flux from large hyper velocity
> impacts over the next few days, and its nice to know
> that you won't be distracting us with dribble.
>
> Now as for your latest nonsense:
>
> "But the fact of the matter is that you can't prove
> "that either an airburst or ice-impact occurred
> "without, in all likelihood, several years, if not
> "decades of intense geological field studies, and this
> "seems to be the point on which our methodologies
> "differ.
>
> Actually, Jason, the isotopic analysis of the IRON
> PEPPER in the mammoth tusks itself is proof enough.
> But the recovery of large iron meteorites from the
> 31,000 BCE iron impact by THE VERY SAME METEORITE
> HUNTERS who use this list could prove the 31,000 BCE
> impact to the MOST DENSE.
>
> And that is one point where our methodologies do
> differ.
>
> good hunting all,
> E.P. Grondine
> Man and Impact in the Americas
>
>
>
>
>
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Received on Mon 24 Dec 2007 07:46:07 PM PST