How was the richat structure formed?

The Richat Structure, also known as the Eye of the Sahara, is a prominent geological formation in Mauritania that spans about 50 kilometers in diameter. It is believed to have formed through a combination of geological processes including erosion and uplift, rather than a meteorite impact as once thought. The concentric rings of the structure are composed of different rock types, revealing layers that have been exposed over time due to erosion. This unique formation has made it a significant site for geological studies and a notable landmark.