Darn New England. Plenty of blow outs and even regs but only about 10,000
years old "dirt".
Yee old glaciers scraped the bed rock clean and replaced the soil with till
which is a jumble. Add the 40-50" of rainfall that perks through this till
each year and it causes havoc to iron. Bog iron is the signature "mineral"
of these parts. Tends to set off detectors readily. But hey, there's always
hope.
Jerry Flaherty
----- Original Message -----
From: "Sterling K. Webb" <[EMAIL PROTECTED]>
To: "Meteorite List" <[email protected]>; "Jerry"
<[EMAIL PROTECTED]>
Sent: Thursday, January 10, 2008 3:46 PM
Subject: Re: [meteorite-list] Fw: Still un answered question
Hi, Jerry, List,
The meteorites of Roosevelt Co. are found in wind-ablated
pits, called "blow-outs," which fill with sand and preserve them.
http://epswww.unm.edu/meteoritemuseum/nmmeteorites.htm
The age of the surfaces that are being searched? 50,000
to 90,000 years old!
http://adsabs.harvard.edu/abs/1992Metic..27..460Z
The abstract:
"We have obtained minimum age estimates for the sand units
underlying the two largest meteorite deflation surfaces in Roosevelt
County, New Mexico, USA, using thermoluminescence dating
techniques. The dates obtained ranged from 53.5 (+/- 5.4) to
95.2 (+/- 9.5) ka, and must be considered lower limits for the
terrestrial ages of the meteorites found within these specific
deflation surfaces. These ages greatly exceed previous
measurements from adjacent meteorite-producing deflation
basins. We find that Roosevelt County meteorites are probably
terrestrial contemporaries of the meteorites found at most
accumulation zones in Antarctica. The apparent high meteorite
accumulation rate reported for Roosevelt County by
Zolensky et al. (1990) is incorrect, as it used an age of
16 ka for all Roosevelt County recovery surfaces.
We conclude that the extreme variability of terrestrial
ages of the Roosevelt County deflation surfaces effectively
precludes their use for calculations of the meteorite accumulation
rate at the Earth's surface."
The full PDF:
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1992Metic..27..460Z&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf
Another area similar to Roosevelt Co. is described
and the mechanism of preservation is given in more detail:
https://e-reports-ext.llnl.gov/pdf/237492.pdf
"Most meteorites from this area have been found on the
floors of active deflation basins (blowouts) that have
been excavated from a mantle of sand dunes. This area
has no apparent fluival or permafrost activity within
the last 50,000 years [e.g., 4,5], suggesting that only
prevailing winds and natural aridity aid in the concentration
and preservation of meteorites."
Has anyone searched this area (Lea Co., NM) further?
(Did it "pan out"?)
Sterling K. Webb
---------------------------------------------------------------------
----- Original Message -----
From: "Jerry" <[EMAIL PROTECTED]>
To: "meteoritelist meteoritelist" <[email protected]>
Sent: Thursday, January 10, 2008 2:10 PM
Subject: [meteorite-list] Fw: Still un answered question
Jerry Flaherty
----- Original Message -----
From: "Matson, Robert D." <[EMAIL PROTECTED]>
To: "Jerry" <[EMAIL PROTECTED]>; "Peter A Shugar" <[EMAIL PROTECTED]>;
"LIST" <[email protected]>
Sent: Thursday, January 10, 2008 1:39 PM
Subject: RE: [meteorite-list] Still un answered question
Nope. Just *ONE* meteorite hunter -- Skip Wilson -- a very methodical
and thorough one. "A meteorite every 22.5 square miles" doesn't really
tell the story -- Skip searched (continues to search?) a much smaller
area than this, but he is very selective about the surfaces searched.
In ideal locations, the meteorite density is much, much higher than
1 per 22.5 square miles. If the average terrestrial lifetime of a
meteorite is, say, 5000 years, the expected density is more like 3
meteorites per square mile. --Rob
P.S. Feel free to forward this to the meteorite list. You'll see
that I included it in the "To" list, but I guarantee it won't show
up there.
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Jerry
Sent: Thursday, January 10, 2008 9:25 AM
To: Peter A Shugar; LIST
Subject: Re: [meteorite-list] Still un answered question
Sounds like ideal search conditions and a hulava lot of meteorite
hunters.
Jerry Flaherty
----- Original Message -----
From: "Peter A Shugar" <[EMAIL PROTECTED]>
To: "LIST" <[email protected]>
Sent: Thursday, January 10, 2008 12:04 PM
Subject: [meteorite-list] Still un answered question
Still unanswered is the other question:
And then there is little dinky Roosevelt Co, NM at just 2,455 sq miles
and
it has a staggering 109 meteorites, which comes to one for every 22.5
sq
miles. What gives?
They are of a wide variety of classifications, so it can't be turning
every piece in
for classification. I can't speak for anyone else, but I find this
very
puzzling.
Any thoughts, List?
Pete
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