[meteorite-list] Holbrook and weathering

From: Matson, Robert <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Thu Apr 22 10:01:29 2004
Message-ID: <AF564D2B9D91D411B9FE00508BF1C86901B4E17F_at_US-Torrance.mail.saic.com>

Hi Steve, Bob and List,

Just read your messages about weathering, and in particular
Steve's reply regarding Holbrook. I just returned from
vacationing in Phoenix, the Grand Canyon (both rims) and
Zion. On Memorial Day I talked my wife into taking a
slightly (!) out-of-the-way path from Phoenix to the south rim
of the Grand Canyon by way of Holbrook. She only had the
patience to stop there a little over an hour, and given
that it was in the early afternoon, it was quite hot.

I'd never been to Holbrook before, so I was happy to find
a tiny Holbrook fragment with nice black crust over half
its exterior. My first meteorite find from a known fall.
It's also my smallest meteorite find -- only 190 milligrams!
Anyone who has been to Holbrook must know that hunting there
is a good exercise in visual signal processing. A lot of
"noise" to filter out...

Coincidentally enough, just minutes after we parked another
vehicle arrived and parked about 50 yards from us. Given that
there's pretty much nothing else around of interest (except
perhaps petrified wood), I figured he had to be a meteorite
hunter. After eyeing each other for a few moments, he was
first to speak -- something along the lines of, "What are you
here for?" I coyly countered, "Same thing you are! ;-)"
That seemed to be an adequate ice-breaker (or an appropriate
exchange of code phrases) and he came over. I'm embarrassed
to say that we never got each other's names, but he said he
was from Bishop (CA) and had purchased meteorites on eBay
before. So, whoever you are, if you happen to be a member
of Meteorite Central -- greetings!

He went off hunting to the north of me, while I headed slowly
eastward. By the time I got back to my car, he had left --
evidently bored, hot, or both. I wish I had had more time
there as I was just getting a feel for the terrain, and
surely would have found more fragments. But we wanted to
get to the G.C. before sunset, so it'll have to wait for
another day.

Steve wrote:

> In my searches of Holbrook, I have found pieces that
> are near to pristine, and others just yards away from
> those that are weathered to the point of being nearly
> unrecognizable.

Given the complicated terrain, I'm not surprised.

> After the initial finds of 1912, I suspect that the
> ever diminishing returns from Holbrook are due more to
> weathering than collecting.

Weathering, combined with a fairly dynamic surface. From what
I saw, stuff is getting alternately buried and exhumed by
wind and water erosion. The small fragment I found was in
a smooth blow-out, where I also found old bullet fragments.

Received on Sun 02 Jun 2002 07:55:05 PM PDT

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