Blue Eye Of Africa

The Richat Structure, also known as the Eye of the Sahara or blue eye of Africa, is a prominent geological circular feature in the Sahara desert in Mauritania near Ouadane. it is nearly 50 kilometers across and very visible from space. Initially interpreted as an asteroid impact structure because of its high degree of circularity, and then as a structure formed by a volcanic eruption that also seems improbable because of the lack of a dome of igneous or volcanic rock, iit is now argued to be a highly symmetrical and deeply eroded geologic dome that collapsed. So it is now thought by many to have been caused by uplifted rock sculpted by erosion. But the fact that the "rings", are equidistant to the centre and that the Richat Structure is nearly circular remains a mystery.