[meteorite-list] Fw: Still un answered question

From: Jerry <grf2_at_meteoritecentral.com>
Date: Thu, 10 Jan 2008 17:04:48 -0500
Message-ID: <9387F13EB53F4865A674D4F01408D34D_at_Notebook>

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" <sterling_k_webb at sbcglobal.net>
To: "Meteorite List" <meteorite-list at meteoritecentral.com>; "Jerry"
<grf2 at verizon.net>
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&amp;data_type=PDF_HIGH&amp;whole_paper=YES&amp;type=PRINTER&amp;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" <grf2 at verizon.net>
> To: "meteoritelist meteoritelist" <meteorite-list at meteoritecentral.com>
> Sent: Thursday, January 10, 2008 2:10 PM
> Subject: [meteorite-list] Fw: Still un answered question
>
>
>
> Jerry Flaherty
> ----- Original Message -----
> From: "Matson, Robert D." <ROBERT.D.MATSON at saic.com>
> To: "Jerry" <grf2 at verizon.net>; "Peter A Shugar" <pshugar at clearwire.net>;
> "LIST" <meteorite-list at meteoritecentral.com>
> 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: meteorite-list-bounces at meteoritecentral.com
> [mailto:meteorite-list-bounces at meteoritecentral.com] 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" <pshugar at clearwire.net>
> To: "LIST" <meteorite-list at meteoritecentral.com>
> 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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Received on Thu 10 Jan 2008 05:04:48 PM PST