The Eye of the Sahara (Mauritania)

The Eye of the Sahara (Mauritania)
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The Africa geological wonder in Mauritania

The massive 40-kilometer diameter circular structure in the Sahara Desert of Mauritania is also known as the Richat Structure or Guell al-Richat. Appearing in a largely featureless desert, this geological marvel resembles an enormous bull’s eye gazing into space from the middle of the Sahara. This huge inverted dome which is actually visible from space, was initially thought to be the result of an asteroid hitting Earth.

The Eye’s location and close-up view

Evidence for this theory was lacking and it is now widely argued to be the result of erosion. Different rates of erosion on the varying rock types have formed concentric ridges. More erosion-resistant rocks form high ridges (blue and purple), while the non-resistant rocks form valleys (yellow). This lead to formation of circular cuestas represented by three nested rings dipping outward from the structure. The center of the structure consists of a limestone-dolomite shelf that encloses a kilometer-scale siliceous breccia and is intruded by basaltic ring dikes, kimberlitic intrusions, and alkaline volcanic rocks.


The Eye of the Sahara

Geologists believe that the Eye of the Sahara is a geologic dome formed millions of years ago. This happened when volcanic activity from deep beneath Earth’s surface lifted the entire landscape around the Eye. These regions were not deserts, as they are today. Instead, they were likely much more temperate, with abundant flowing water. Layered sandstone rocks were deposited by blowing winds and on the bottoms of lakes and rivers during the temperate. The subsurface volcanic flow eventually pushed up the overlying layers of sandstone and other rocks. After the volcanism died down, wind and water erosion began to eat away at the domed layers of rock. The region began to settle down and collapse in on itself, creating the roughly circular “eye” feature.

aerial view

Northwest of the eye is with Kediet ej Jill Mountain, Mauritania’s highest peak (nearly 1000 meters). The mountain has a large concentration of magnetite, giving it a blueish tinge and totally messing up magnetic surveys and navigation nearby. The Western Sahara fills the northern part.

The Eye of the Sahara attracts tourists and scholars, who flock to see/study the unique geological feature in person.  The future of the Eye is open to the vagaries of nature. Erosion threatens its landscape while desert winds may bring more dunes to the region submerging it with sand and dust

Check other interesting geologies in Africa at:


  1. Amazing, the wonders of nature and the use of satellite imagery to discover this feature… Mind blowing


  2. This is the sought out entrance, the door to hell gentlemen, which Adolf Hitler sought in vain.


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