Richat Structure

The Eye of the Sahara

Deep in the heart of the Sahara desert lies a natural wonder that has puzzled scientists and intrigued travelers for decades. The Richat Structure, also known as the Eye of the Sahara, is a circular geological formation in Mauritania, Northwest Africa. Spanning over 25 miles (40 kilometers) in diameter, it is one of the largest and most unique geological structures on our planet.

Richat Structure, Mauritania ©JAXA/ESA

Richat Structure, Mauritania ©JAXA/ESA

The Richat Structure was first observed by astronauts aboard the Gemini spacecraft in the 1960s. Its circular shape and symmetrical patterns immediately caught the attention of the scientific community, and over the years, numerous studies have been conducted to determine its origin.

At first, geologists thought the Eye of the Sahara was a result of a meteor impact due to its circular shape. But after studying the rocks for a long time, they discovered it is actually Earth-based and is now widely accepted as a natural phenomenon.

The ancient rocks in the Eye of the Sahara also tell us how it came to be. The structure comprises various rock layers like sandstone, limestone, and volcanic rocks between 100 and 600 million years old.

The inner ring of the Richat Structure

The inner ring of the Richat Structure

It all started when Pangaea (a massive ancient supercontinent with all the continents joined together) began to split. Water from the Atlantic Ocean started to fill the space. While Pangaea was breaking, hot magma from deep inside the Earth pushed up. This made a circle of hard rock with sandstones on top.

Millions of years in the past, these places weren’t deserts like they are today. They probably enjoyed a milder climate with lots of flowing water. The wind carried sand, layering it. Lakes and rivers added more layers at the bottom. Under the surface, volcanic forces pushed the upper sandstone and rock layers up. When the volcanic activity calmed, wind and water started wearing down the curved rock layers. Slowly, the land sank and collapsed, forming the round “eye” shape we see today.

Richat Structure. A topographic reconstruction from satellite photos.

Richat Structure. A topographic reconstruction from satellite photos. False coloring as follows: Brown—bedrock; Yellow/white—sand; Green—vegetation; Blue—salty sediments.

A unique theory proposed that the Richat Structure might be Atlantis, the legendary lost city described by Plato. Atlantis was said to have rings too. However, reality is more scientific than myth. Archaeologists have found various stone tools made by early humans, like Homo erectus, mainly in the outer ring. These tools, like spearheads, pottery fragments, and ship anchors, are made from local quartzite. So, the Richat Structure is not only a geological wonder but also holds a fascinating human history.

Editors’ finds

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Words of wisdom

“What makes the desert beautiful is that somewhere it hides a well.” —Antoine de Saint-Exupéry, The Little Prince

“What is a friend? A single soul dwelling in two bodies.” ―Aristotle

“I know not all that may be coming, but be it what it will, I'll go to it laughing.” ―Herman Melville, Moby-Dick or

“A room without books is like a body without a soul.” ―Marcus Tullius Cicero


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