[meteorite-list] Sounds like prime meteorite hunting territory

From: Darren Garrison <cynapse_at_meteoritecentral.com>
Date: Fri, 08 May 2009 22:26:23 -0500
Message-ID: <apt9055jfqf5lnuh627nmgfp65ujungbtm_at_4ax.com>

http://www.itwire.com/content/view/24922/1066/

Israeli desert is oldest known surface on Earth E-mail
by William Atkins
Saturday, 09 May 2009

Israeli ?French-U.S. scientists have confirmed that the oldest large-area
surface on Earth is found in the Paran Plain (within the desert regions of the
Sahara and Arabia) in southern Negev, Israel. The surface is estimated to be 1.5
to 1.8 million years old.

It is noted that there are individual rocks, which have previously been
analyzed, that are much older than this large-surface area, but this area in
Israel is considered to be the oldest substantial area on the surface of the
Earth.

Because of erosion and general weathering, tectonic plate activity, and other
such factors, most surfaces on Earth are relatively new in age, at least when
compared to this very old spot.

In fact, this newly found spot is over four times older than the previously
known oldest spot, which is in Death Valley in Nevada (in the United States).

The article ?Desert pavement-coated surfaces in extreme deserts present the
longest-lived landforms on Earth? in the GeoScienceWorld Bulletin is authored by
Ari Matmon, from The Institute of Earth Sciences, Hebrew University of
Jerusalem, Israel, and his colleagues: Ori Simhai, Rivka Amit, Itai Haviv, Naomi
Porat, Eric McDonald, Lucilla Benedetti, and Robert Finkel.

Desert pavements are surfaces found in deserts that are covered with dense,
interlocking rock fragments.

The researchers state in their GSW Bulletin article that, ?All exposed rocks on
Earth's surface experience erosion; the fastest rates are documented in rapidly
uplifted monsoonal mountain ranges, and the slowest occur in extreme cold or
warm deserts?millennial submeter-scale erosion may be approached only in the
latter."

And, "The oldest previously reported exposure ages are from boulders and clasts
of resistant lithologies lying at the surface, and the slowest reported erosion
rates are derived from bedrock outcrops or boulders that erode more slowly than
their surroundings; thus, these oldest reported ages and slowest erosion rates
relate to outstanding features in the landscape, while the surrounding landscape
may erode faster and be younger.?

A photograph of the surface is found on LiveScience.com. Its description says,
"Desert pavement formed long ago in an area that is extremely flat and arid,
where tectonic activity is low and rocks are highly resistant to weathering. A
pencil is shown for scale."

The age of the surface was determined by measuring the concentration of 10Be, an
isotope, which is produced when a material is exposed to Earth?s atmosphere.

The isotope 10Be is a beryllium isotope that is produced in the Earth?s
atmosphere by the interaction of the elements oxygen and nitrogen with cosmic
rays coming in from outer space.

The isotope accumulates in soils but decays gradually (half-life of 1.51 million
years) into 10B, a boron isotope.

Dr. Matmon stated, "The surface we dated most likely represents large areas in
the Sahara and Arabia Deserts. We hope to be able to collect samples from other
locations in the Sahara and Arabia Deserts and establish the global extent of
these old surfaces."
Received on Fri 08 May 2009 11:26:23 PM PDT