The Eye of the Desert is a geological mystery that “stares” into space.

The Eye of the Desert is a geological mystery that “stares” into space.

WWhen viewed from above, the Ain al-Sahara looks like a massive impact crater located in the middle of the Sahara Desert in Mauritania. Stretching 50 km This crater is 30 miles in diameter, consists of a series of regular undulations, and is actually entirely land.

These are amazing old ones Geological The formation was used in the 1960s by Gemini astronauts as a landmark. Geologists first The Ain Al Sahara, also known as the Rishat Structure, is believed to be a massive impact crater. However, additional studies of the sedimentary rocks that make up the central dome have dated the formation to the late Proterozoic Era, between 1 billion and 542 million years ago.

It’s worth noting that some still believe the structure is actually the remains of the lost city of Atlantis, as its circular shape is said to resemble the Earth described by Plato – but we’re not enjoying that here.

The structure was likely actually formed by a process called “folding”, creating what is called a symmetrical anticline. Folding occurs when tectonic forces acting from both sides press down on sedimentary rocks. If the rocks are cold and brittle they can break, but if they are warm enough, they will become folds. Upward folds are called anticlines, while downward folds are called synclines.

However, in a 2014 paper published in the Journal of African Geosciences, researchers proposed a completely different explanation for the eye’s formation. The presence of volcanic rocks is said to indicate evidence of molten rock being pushed to the surface, causing the dome shape, before it eroded into the rings we see today. The paper suggested that the separation of the supercontinent Pangea may have played a role in these volcanic formations and tectonic shifts.

The structure consists of a mixture of sedimentary and igneous rocks. Erosion across the surface of the structure exposes fine-grained rhyolite and coarsely crystalline gabbro rocks that have undergone hydrothermal alteration. The types of rocks across the rings erode at different speeds, creating different colored patterns across the surface. Large, sharp-angled fragments of sedimentary rock called megabreccia add to the colorful, swirling irregularities that make up the formation.

The center of the dome contains a shelf of limestone and dolomite with kilometer-wide breccia, ring dikes, and alkaline volcanic rocks. The eye’s complex geological structure has puzzled and intrigued geologists since its discovery, and it is still widely considered one of the most impressive geological features in the world. As such, in 2022 it became one of the first 100 geoheritage sites recognized by the International Union of Geological Sciences (IUGS).

Due to its vast size, the Eye of the Sahara is best viewed from great heights (preferably space), so we will now have to rely on satellite images to enjoy all its glory.

A previous version of this article was published in January 2023.

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