The Mysterious Richart Structure in the Sahara

For millennia, the Eye of the Sahara was hiding in plain sight.

That's because this huge and mysterious geologic formation is hard to spot from ground level, walking around on Earth.

It turns out that we really discovered this incredible bull's-eye in the sand only when we began sending humans into space.  And we were able to learn even more about it from high resolution satellite images.

But even now that we've found it, scientists don't fully understand it.

The Eye of the Sahara, more formally known as the Richat structure, is in the western Sahara Desert in Mauritania. On the ground, it's about 25 miles across.

For a while, scientists did think that the Eye of the Sahara was an impact crater. But they didn't find enough melted rock to make that guess hold water. Current theories suggest a much more complicated story behind this incredible natural formation.

The main ring structure of the Eye is the eroded remains of what was once a dome of layers of Earth's crust.

Scientists still have questions about the Eye of the Sahara, but two Canadian geologists have a working theory about its origins.

They think that the Eye's formation began more than 100 million years ago, as the supercontinent Pangaea was ripped apart by plate tectonics and what are now Africa and South America were being torn away from each other.

Molten rock pushed up toward the surface but didn't make it all the way, creating a dome of rock layers, like a very large pimple. This also created fault lines circling and crossing the Eye. The molten rock also dissolved limestone near the center of the Eye, which collapsed to form a special type of rock called breccia.

A little after 100 million years ago, the Eye erupted violently. That collapsed the bubble partway, and erosion did the rest of the work to create the Eye of the Sahara that we know today. The rings are made of different types of rock that erode at different speeds. The paler circle near the center of the Eye is volcanic rock created during that explosion.

We have 2 designs that are located near the Sahara, showing the beauty of this area on our planet.  One is from the Nearby Atlas Mountains, and the other is an ancient riverbed on the northern edge of the Sahara, near Ghadamis.