Richat Structure - Wikipedia, the free encyclopedia
en.wikipedia.org/wiki/Richat_Structure
Article
Richat Structure
Circular geological feature in the Sahara desert
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
The Richat Structure, also known as the Eye of the Sahara and Guelb er Richat, is a prominent circular feature in the Sahara desert of westcentral Mauritania near Ouadane. This structure is a deeply eroded, slightly elliptical, 40-km in diameter, dome. The sedimentary rock exposed in this dome range in age from Late Proterozoic within the center of the dome to Ordovician sandstone around its edges. The sedimentary rocks comprising this structure dip outward at 10-20. Differential erosion of resistant layers of quartzite has created high-relief circular cuestas. Its center consists of a siliceous breccia covering an area that is at least 3 km in diameter.