[meteorite-list] Cold hunting?

From: Matson, Robert <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Thu Apr 22 10:29:54 2004
Message-ID: <AF564D2B9D91D411B9FE00508BF1C86901B4ED48_at_US-Torrance.mail.saic.com>

Hi Sterling and List,

Sterling wrote:

> Taking the area of the Earth to be 5.1 x 10^8 km^2 and the
> meteorite flux to be 23,930 yr^-1 (that's the figure from
> the MORP study), this yields the assumed collisional cross
> section of the earth to be 21,360 km^2 yr^-1. This rate
> means that one meteorite per year falls on an area of
> 21,320 square kilometers.

> ... Of course, I think the MORP fall rate is too low and the
> real fall rate could be 3-4 times higher.

Yes -- the MORP study rate is definitely too low. If there's
a researcher out there that would be interested in terrestrial
age-dating a representative sampling of my finds, we could
place a nice lower bound on the annual fall rate.

> A meteorite could fall on every square kilometer every
> 6,000 years or so. In that case, if a meteorite lasted
> 40,000 years and one fell every 6,000 years, they're be
> five or six on every square kilometer.

One of our list geologists could better assess the span of
time that southern California and southern Nevada playas
have been "dry" -- for example, up until about 15,000
years ago, Lake Manix covered a couple hundred square
miles of the region around Barstow. Thus, I wouldn't
expect to find meteorites older than 15,000 years from
this zone. The earthquake that drained Lake Manix sent
the water in the direction of Silver and Soda dry lakes
near Baker, so these areas remained wet even more recently.
On average, I wouldn't expect to find more than about
3 unpaired meteorites per square kilometer in these areas.

In well grid-searched areas, the Mojave recovery rate
approaches and occasionally exceeds 1 unpaired find per
square kilometer. Walking at 5 km/hour with a maximum
detection range of +/- 10 meters, such an area can be
searched in 10 hours (though most people aren't likely
to walk over 30 miles in a single day!) Choose your
search locations intelligently, and finding meteorites
is reduced to a problem of focus and perseverance.

--Rob
Received on Thu 11 Sep 2003 06:36:02 PM PDT