So what could this be? Just calling it erosion seems a little too simple. This thing is 30 miles wide, circular and only exists in one place in the world. There's gotta be something more than just erosion.... any thoughts?

http://earthobservatory.nasa.gov/Newsroom/NewImages/Images/aster_richat_lrg.jpg

This prominent circular feature in the Sahara desert of Mauritania 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 kilometers (30 miles)] has become a landmark for shuttle crews. Initially interpreted as a meteorite impact structure because of its high degree of circularity, it is now thought to be merely a symmetrical uplift (circular anticline) that has been laid bare by erosion. Paleozoic quartzites form the resistant beds outlining the structure.

This image was acquired on October 7, 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.



http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=9319

Tam,
That is wild. I never knew this was even was out there.
Do they have pictures of what it looks like closer, meaning if you were standing in the circle looking out? That's hard to believe it's just erosion. Why doesn't it happen any where else in the world?

I'm going to look up more information. It sure is pretty though.

It says here that the so-called Richat Structure is a geological formation in the Maur Adrar Desert in the African country of Mauritania. Although it resembles an impact crater, the Richat Structure formed when a volcanic dome hardened and gradually eroded, exposing the onion-like layers of rock.

http://landsat.gsfc.nasa.gov/earthasart/richat.html

Seeing if I can find some close up pictures.

volcanic? hmmmm

This is what Nasa's Picture of the day (http://antwrp.gsfc.nasa.gov/apod/ap021028.html) says:

The Richat Structure in the Sahara Desert of Mauritania is easily visible from space because it is nearly 50 kilometers across. Once thought to be an impact crater, the Richat Structure's flat middle and lack of shock-altered rock indicates otherwise. The possibility that the Richat Structure was formed by a volcanic eruption also seems improbable because of the lack of a dome of igneous or volcanic rock. Rather, the layered sedimentary rock of the Richat structure is now thought by many to have been caused by uplifted rock sculpted by erosion. The above image was captured last year by the orbiting Landsat 7 satellite. Why the Richat Structure is nearly circular remains a mystery.

Your nasa source says something else, seems like those guys need to start communicating more...

Your nasa source says something else, seems like those guys need to start communicating more...

Yes it seems they should. It's still remains a mystery.
I still can't find any pictures of it close up. I wonder if there are people living around it? I wonder if they have stories of their own to tell about the Richat Structure?

Look there is another one, but much smaller. Check this picture out.

Semsiyat dome (http://www.image-contrails.de/mauritania/mauritania-met-semsiyat-dome.html) , 50 km west-southwest of Richât and centered at latitude 210°'N and longitude 1105°'W, has a diameter of 5 km. Although the style of deformation is similar to that of Richât, Semsiyat is barely detectable on the ground. The structure lies on the Chinguetti Plateau and has only a few meters of topographic relief. Strata dip so slightly that field measurement is difficult. Exposures are poor, and the rocks are extremely weathered. No evidence of shock metamorphism has been discovered at Semsiyat; like Richât, it is believed to be a dome of endogenic origin (Dietz et al., 1967). (GCW: J. R. Underwood

http://www.image-contrails.de/images/mauritania/richat-near.jpg

looks like someone needs clear eyes

That's a beautiful................whateveritis. I can tell you right now that it ain't just an eroded cone. There is no granitic evidence of a pluton. Furthermore, cones don't just level off. They deteriorate in layers rather than uniformly.

You've just inspired this week's search.