When viewed from above, the Eye of the Sahara or the Eye of the Sahara looks like an eye that appears to stare into outer space. The Eye of the Sahara is actually a large impact crater in the middle of the Sahara Desert in Mauritania, in the northwestern part of the African continent.
The Eye of the Sahara is a circular geological structure with a diameter of 50 kilometers. This spectacular ancient geological formation was used in the 1960s by Gemini astronauts as a landmark.
Geologists initially believed the Eye of the Sahara, also known as the Richat Structure, to be a massive impact crater. However, further studies into the sedimentary rocks that make up the central dome, determined that the structure was formed in the late Proterozoic era, between 1 billion and 542 million years ago.
Quoted from IFL Science, some people still believe that the structure is actually the remains of the lost city of Atlantis, because its circular shape resembles the land described by Plato. However, there were no further findings to support this belief.
The structure most likely actually formed through a process called "folding", creating what's called a symmetrical anticline. Folds occur when tectonic forces acting from both sides compress the sedimentary rock. If the rock is cold and brittle, it can fracture. But if it's warm enough, it will fold. An upward fold is called an anticline, while a downward fold is called a syncline.
However, in a 2014 paper published in the Journal of African Earth Sciences, researchers proposed a very different formation explanation to explain the Eye of the Sahara phenomenon.
According to the researchers, the presence of volcanic rock indicates evidence of molten rock being pushed to the surface, causing the dome to form, before eroding into the rings we see today. The paper proposes the theory that the breakup of the Pangea supercontinent may have played a role in these volcanic formations and tectonic shifts.
The structure of the Eye of the Sahara consists of a mixture of sedimentary and igneous rocks. Erosion over the entire surface of the structure revealed fine rhyolite and coarse crystalline gabbro that had undergone hydrothermal alteration.
The rock types found throughout the ring eroded at different rates, creating different colored patterns across the surface. Large, sharply angled fragments of sedimentary rock called megabreccia add to the irregularity of the colorful swirling patterns that make up this formation.
Meanwhile, the center of the dome is known to contain a one-kilometer-wide limestone-dolomite bed of breccias, ring embankments, and alkaline volcanic rocks. The complex geological structure of the Eye of the Sahara has puzzled and intrigued geologists since its discovery.
Today, the Eye of the Sahara is still considered one of the most impressive geological features in the world. In 2022, the Eye of the Sahara will become one of the first 100 geological heritage sites to be recognized by the International Union of Geological Sciences (IUGS).
Due to its large size, the Eye of the Sahara is best seen from a great height, if possible from outer space. So for now we can only rely on satellite imagery to see it in its entirety.