Largest Crater in the Great Sahara Discovered by Boston University Scientists

http://www.bu.edu/phpbin/news/releas...ay.php?id=1073

For Release Upon Receipt - March 3, 2006
Contact: Kira Edler, 617-358-1240,

LARGEST CRATER IN THE GREAT SAHARA DISCOVERED BY BOSTON UNIVERSITY
SCIENTISTS

Researchers from BU's Center for Remote Sensing locate crater using
detailed satellite data

(Boston) - Researchers from Boston University have discovered the
remnants of the largest crater of the Great Sahara of North Africa,
which may have been formed by a meteorite impact tens of millions of
years ago. Dr. Farouk El-Baz made the discovery while studying
satellite
images of the Western Desert of Egypt with his colleague, Dr. Eman
Ghoneim, at BU's Center for Remote Sensing.

The double-ringed crater - which has an outer rim surrounding an inner
ring - is approximately 31 kilometers in diameter. Prior to the latest
finding, the Sahara's biggest known crater, in Chad, measured just over
12 kilometers. According to El-Baz, the Center's director, the crater's
vast area suggests the location may have been hit by a meteorite the
entire size of the famous Meteor (Barringer) Crater in Arizona which is
1.2 kilometers wide.

El-Baz named his find "Kebira," which means "large" in Arabic and also
relates to the crater's physical location on the northern tip of the
Gilf Kebir region in southwestern Egypt. The reason why a crater this
big had never been found before is something the scientists are
speculating.

"Kebira may have escaped recognition because it is so large - bigger
than the area of 125 football fields, or the total expanse of the Cairo
urban region from its airport in the northeast to the Pyramids of Giza
in the southwest," said Dr. El-Baz. "Also, the search for craters
typically concentrates on small features, especially those that can be
identified on the ground. The advantage of a view from space is that it
allows us to see regional patterns and the big picture."

The researchers also found evidence that Kebira suffered significant
water and wind erosion which may have helped keep its features
unrecognizable to others. "The courses of two ancient rivers run
through
it from the east and west," added Ghoneim.

The terrain in which the crater resides is composed of 100 million
year-old sandstone - the same material that lies under much of the
eastern Sahara. The researchers hope that field investigations and
samples of the host rock will help in determining the exact age of the
crater and its surroundings.

Kebira's shape is reminiscent of the many double-ringed craters on the
Moon, which Dr. El-Baz remembers from his years of work with the Apollo
program. Because of this, he believes the crater will figure
prominently
in future research in comparative planetology. And, since its shape
points to an origin of extraterrestrial impact, it will likely prove to
be the event responsible for the extensive field of "Desert Glass" -
yellow-green silica glass fragments found on the desert surface between
the giant dunes of the Great Sand Sea in southwestern Egypt.

Dr. El-Baz is research professor and Director of the Center for Remote
Sensing at Boston University. He is a renowned geologist who over the
past 30 years has conducted studies in all the major deserts of the
world. He is a member of the U.S. National Academy of Engineering and a
Fellow of the American Association for the Advancement of Sciences and
the Geological Society of America. The latter established the "Farouk
El-Baz Award for Desert Research" to reward excellence in arid land
studies.

Dr. Eman Ghoneim is a research associte at the Center for Remote
Sensing. She is an expert in hydrological modeling and now conducts
research on arid land geomorphology with emphasis on groundwater
concentration under the direction of Dr. El-Baz.

The Boston University Center for Remote Sensing is a research facility
that was established in 1986. Researchers at the Center apply
techniques
of remote sensing and geographic information systems (GIS) to research
in the fields of archaeology, geography and geology. In 1997, the
Center
was recognized by NASA as a "Center of Excellence in Remote Sensing."

Founded in 1839, Boston University is an internationally recognized
institution of higher education and research. With more than 30,000
students, it is the fourth largest independent university in the United
States. BU contains 17 colleges and schools along with a number of
multi-disciplinary centers and institutes, which are central to the
school's research and teaching mission.

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Note to editors: Images available online at
http://www.bu.edu/remotesensing/News/kebira/index.html