Richat Structure

The Richat Structure, a prominent circular feature in the Sahara desert of Mauritania near Ouadane, has attracted attention since the earliest space missions because it forms a conspicuous bull's-eye in the otherwise rather featureless expanse of the desert. Described by some as looking like an outsized ammonite in the desert, the structure, which has a diameter of almost 50 kilometres (30 miles), has become a landmark for space shuttle crews. Initially interpreted as a meteorite impact structure because of its high degree of circularity, it is now thought to be a symmetrical uplift (circular anticline or dome) that has been laid bare by erosion. Paleozoic quartzites form the resistant beds outline the structure. However, a line drawn 208° S-SW between the Temimichat impact crater and the Tenoumer impact crater, themselves separated by 166 kilometers, intersects the exact center of the Richat structure, 390 km away.

"Original entry was from the NASA Earth Observatory; [http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=9319] "

Further reading

*cite journal |author=Guillaume Matton, Michel Jébrak and James K.W. Lee |title=Resolving the Richat enigma: Doming and hydrothermal karstification above an alkaline complex |journal=Geology |year=2005 |month=August |volume=33 |issue=8 |pages=665–668 |doi=10.1130/G21542.1

External links

* [http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=9319 NASA Earth Observatory page]
* [http://antwrp.gsfc.nasa.gov/apod/ap021028.html Astronomy Picture of the Day]
* [http://www.googlesightseeing.com/?p=396 Google Sightseeing]
* [http://www.wikimapia.org/#y=21117811&x=-11423721&z=11&l=0&m=a&v=2 wikimapia]
* [http://www.saharamet.com/expedition/2003/crater.html Visit to Temimchat and Tenoumer craters]