Planetary News: Earth (2006)
Egyptian Impact Site:
Possible Source of Libyan Desert Glass Discovered
March 3, 2006
According to a news
item in this week's issue of Science magazine, planetary scientist
Farouk El-Baz has just discovered "the largest crater yet found in
the Sahara," and is suggesting that it has the right characteristics
to answer a long-standing mystery. Since 1932, scientists have been
picking up yellow-green glass in a 60-by-100-kilometer (35-by-60-mile) area
of the desert of southern Egypt near the Libyan border. Study of the glass
has revealed the unmistakable isotopic signature of an asteroid impact,
but the source crater has never been found -- until now.
El-Baz says that the crater he discovered is 30 kilometers in diameter, large
enough to be the source of the glass. The crater is located in the Gilf
Kebir plateau, an area previously identified by researcher Philippe Paillou
of the Observatoire Aquitain des Sciences de L'Univers to be the largest impact
crater field on Earth. The extreme conditions of the Sahara desert act
to preserve impact crater structures, though the crater that El-Baz discovered
and named "Kebira" (an Arabic word meaning "great" or "powerful")
was difficult to see because of its large size and dissection by ancient
rivers during a time when the region was wetter than it is now.
Saharan crater
This is an unnamed 950-meter-diameter crater in the Gilf Kebir plateau
of southwestern Egypt. The newly discovered crater Kebira is more than 30
times the diameter of this one. Credit: CRAS / Elsevier
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