The Richat Structure: Eye of the Sahara

A Geological Enigma

From space, the feature resembles a giant ammonite or a bullseye. For decades, the origin of the Richat Structure in Mauritania was a mystery. Initially thought to be an asteroid impact crater, it is now understood by geologists to be a highly symmetrical and deeply eroded geologic dome.

What Our Satellites See

Images from Landsat and Sentinel-2 reveal the intricate layers of sedimentary rock and igneous intrusions. The rings are composed of different types of rock that erode at different rates, creating the stark circular ridges. The different colors in satellite imagery correspond to these varying rock types.

• Paleozoic quartzites form the resistant central ridges.
• Volcanic rocks (gabbros and kimberlites) are visible as darker intrusions.

This natural wonder serves as a landmark for shuttle crews and a subject of intense study for geologists, reminding us of the powerful geological forces that shape our planet's surface.