“Located western edge of Sahara desert at central Mauritania in northwest Africa, there is a giant circle called Richat Structure, whose diameter ranges as long as 38km.
First, Richat structure was considered an impact crater. However, by the fact that it doesn’t contain any particular mineral and that the depth is too shallow for its diameter, it is considered a dome structure formed by intrusive rock. Rim of the dome is composed of quartzite, which is quite strong against erosion and higher than the surrounding area by about 100mt.
As seen at the upper part of the image, Makteir sand dune spreads to the north of Richat Structure.”
The huge eye of the earth in the Sahara desert, Richat Structure, Mouritania.. source
