Richat Structure - Giant Blue Eye of Sahara Desert

The Richat Structure is also known as the Eye of the Sahara or Blue Eye of Africa. The circular shape of richat structure in Africa's Sahara Desert is surrounded by secrets. This wonderful structure can be seen not only from earth but also from space. It is a prominent circular feature in the Sahara near Ouadane, west–central Mauritania. There are many controversies about its existence. The sedimentary rock exposed in this dome ranges 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 30 kilometres in diameter. The Richat Structure is a deeply eroded, slightly elliptical dome with a diameter of 40 kilometres.

Exposed within the interior of the Richat Structure are a variety of intrusive and extrusive igneous rocks. They include rhyolitic volcanic rocks, gabbros, carbonatites and kimberlites. According to field mapping and aeromagnetic data, the gabbroic rocks form two concentric ring dikes. The inner ring dike is about 20 m in width and lies about 3 km from the center of Richat Structure. The outer ring dike is about 50 m in width and lies about 7 to 8 km from the center of this structure. Thirty-two carbonatite dikes and sills have been mapped within the Richat Structure. The dikes are generally about 300 m long and typically 1 to 4 m wide. They consist of massive carbonatites that are mostly devoid of vesicles. Firsty It was interpreted as an asteroid impact structure because of its high degree of circularity, the Richat Structure is now regarded by geologists as a highly symmetrical and deeply eroded geologic dome.  However, the scientists who have applied the ideas after a long search are quite factual. It is being said that several years ago this area of Sahara was completely covered with sea. Then there was gradual change and this area was transformed into the world's largest desert. Due to the shrinking nature of water and sand together formed a shape that began to look like an eye. Later, it was called as Eye of the Sahara. However, this is not the only one such structure. Many such shapes are also seen in other parts of the Earth, including Belize's Great Blue Hole.