The Richat Structure in the Mauritanian desert is a 40-kilometer-wide geological formation featuring perfect concentric circles visible from space, often misidentified as the lost city of Atlantis or a meteor impact zone, but actually proven to be an eroded geological dome created by rising molten rock.
French Geographers Map the Desert Anomaly
Western geologists have known about the remote Mauritanian phenomenon on the Adrar Plateau at least since the 1930s, when French geographers first put the site on the map. This vast expanse of the Sahara desert—which makes up 90 percent of Mauritania—harbors a wide variety of wildlife from wild dogs and camels to birds, reptiles, ants, scorpions, and jerboas.
For decades, researchers debated whether natural forces could produce such perfect geometric shapes from above. Speculation ranged from molten rock pushing up from below to extraterrestrial rock striking from above.
The Impact Crater Confusion of the Mid-Century
Naturalist Théodore Monod discovered three significant impact craters—Aouelloul, Temimichat-Ghallaman, and Tenoumer—near the Richat Structure in 1952. This discovery shaped early geological theories. In 1948, geographer Jacques Richard-Molard had speculated that the structure formed from magma rising through the Earth’s crust. However, after the discovery of the nearby impact sites, mainstream consensus shifted to classify the Richat Structure alongside them.
The Richat Structure: the 25 mile wide ‘Eye of the Sahara’Deep in Mauritania’s Sahara Desert, this enormous geological formation creates a striking bullseye pattern visible from space. Its unusual shape even made it a useful landmark for astronauts in orbit pic.twitter.com/xzarxeFZa1
That consensus held until American geologist Robert Fudali demonstrated in 1969 that the Richat Structure could not be an impact crater like the other three. The site had never been hit by a meteor.
Astronaut Photography Fuels the Atlantis Myth
In 1965, astronauts Ed White and James McDivitt flew the Gemini IV space mission, during which they completed the first US spacewalk. The photograph they captured from orbit fanned the flames of the Richat Structure debate, earning the landmark the moniker “The Eye of the Sahara.”
The sheer scale of the 25-mile-wide formation means an observer standing on the ground would have no visual indication they were inside a circle. This monumental scale, combined with its circular geometry, inspired widespread speculation that the location served as the utopian society described by Greek philosopher Plato around 360 BCE. Geologists easily discredit this lost city theory by pointing out the extreme age of the rocks.
Erosion Exposes Ancient Artifacts
A paper published in the journal Geology by Guillaume Matton, Michel Jébrak, and James Lee finally settled the primary debate in 2005. The research determined that the site is an eroded geologic dome formed when molten rock pushed up from beneath the surface.
Wind and sand erosion over millions of years carved the original dome into the circular ridges visible from space, leaving the oldest rocks at the center and the youngest at the edges. While the structure predates humans by tens of millions of years, archaeologists have found substantial evidence of early human habitation. Researchers recovered Acheulean stone tools, Neolithic spears, and middle-to-late Pleistocene stone artifacts left by Homo erectus and Homo heidelbergensis mostly concentrated in the outermost ring, alongside unexcavated stone burial mounds.
