Richat Structure
From the ground it looks like a series of rocky ridges in the Sahara. From orbit, it reveals itself as one of the most striking geological features on Earth: a 50-kilometre-wide bullseye of concentric rock rings, so prominent that early astronauts used it as a navigation landmark. This is the Richat Structure — also called the Eye of Africa.
At a glance
The Richat Structure lies on the Adrar Plateau of the Sahara, in the Adrar Region of Mauritania, approximately 40 kilometres west of the town of Ouadane. It measures roughly 50 kilometres in diameter — large enough to contain a medium-sized city. The concentric rings are composed of different rock types of different ages and hardness: the outermost rings are limestone and sandstone; inner rings expose progressively older rocks including quartzite; the central dome is rhyolite and gabbro, among the oldest rocks at the surface.
Despite its dramatic appearance, the Richat Structure is not a meteorite impact crater. It is a geological dome — a region where Earth’s crust was pushed upward over millions of years, then eroded from the centre outward, exposing the different rock layers as concentric rings.
How it formed
The Richat Structure began forming in the Proterozoic era, roughly 100 million years ago, when magma intruded into the sedimentary rock of the Taoudeni Basin and domed the overlying layers upward. Over tens of millions of years, erosion stripped away the top of the dome and worked downward through the concentric rock layers, carving the bull’s-eye pattern we see today. Each ring represents a layer of rock of different hardness: harder quartzite ridges project above the surface; softer limestone and sandstone between them have been worn down into the ring-shaped valleys.
The structure was initially thought to be a meteorite impact crater when seen from space — circular features of that scale typically are. Detailed geological study in the 1990s and 2000s ruled out an impact origin: there are no shock-metamorphosed minerals, no melt rocks, and the geometry matches dome erosion rather than impact mechanics. The scientific consensus today is clear: purely geological.
Discovery from space
The Richat Structure was first documented from the air and ground in the 1950s, but its true scale was only apparent when the Gemini IV mission in 1965 photographed it from orbit. Astronauts James McDivitt and Ed White reported seeing the circular feature and used it — together with a few other prominent landmarks — as a visual reference for tracking their position over the Sahara during passes without electronic navigation aids.
Subsequent Landsat satellite imagery made the structure famous in the geological and educational community. Today, images of the Richat Structure are among the most widely reproduced satellite photographs of the African continent.
The Atlantis theory: what it says and why it is wrong
In 2018, a YouTube video by the channel “Bright Insight” argued that the Richat Structure was the original site of Atlantis, as described by the ancient Greek philosopher Plato in the dialogues Timaeus and Critias. The argument rested on three apparent coincidences: the concentric ring pattern (Plato described Atlantis as a city of concentric rings of water and land), the structure’s size (~50km), and its location near the Atlantic Ocean.
The theory does not hold up to scrutiny. Plato dated Atlantis to 9,000 years before his time (~9,600 BC) and described it as an island city in the ocean, inhabited by a technologically advanced seafaring civilization. The Richat Structure’s rocks are 100 million years old; there is no evidence of any ancient city, harbour, or human settlement here; and the rings are solid rock, not alternating rings of water and land. The geological evidence is unambiguous. The video nonetheless generated tens of millions of views and measurably increased tourist interest in Mauritania — which is one reason the structure is better known today than it was a decade ago.
Visiting the Eye of Africa
The Richat Structure is one of the more remote travel destinations in this guide. Ouadane, the nearest town, is itself a UNESCO World Heritage site — a medieval trading city abandoned in the 17th century and partially inhabited today. Reaching the structure from Ouadane requires a 4WD vehicle and a local guide; no marked trail or visitor infrastructure exists at the structure itself.
The visual experience from the ground is unlike the satellite view. Visitors typically drive across the outer rings along traditional camel routes, observing the ridges of quartzite and the subtle colour changes between rock types. The scale is impossible to grasp at ground level; the best views of the full structure require elevation — or a drone. Annual camel treks pass through the area as part of trans-Saharan routes.
Key facts
- Location: Adrar Region, Mauritania (21.12°N, 11.40°W)
- Diameter: Approximately 50 kilometres
- Age: c. 100 million years (Proterozoic geological formation)
- Rock types: Outermost rings: limestone, sandstone; inner rings: quartzite; central dome: rhyolite and gabbro
- Discovery from orbit: Gemini IV mission, June 1965 (McDivitt and White)
- Heritage status: No UNESCO designation; Ouadane town nearby is a UNESCO WHS (2007)
Practical information
- Nearest town: Ouadane (~40 km); itself requires a full-day drive from Atar on piste roads
- Access from Atar: ~200 km on piste; 4WD mandatory; fuel for the round trip must be carried
- Guides: Mandatory for the structure itself; bookable through tour operators in Atar or Nouakchott
- Best season: November–March (cooler Saharan temperatures; July–September reaches 45°C)
- Visas: Most nationalities require a Mauritanian visa; available on arrival at Nouakchott airport
Nearby
- Ouadane — 40 km east; medieval UNESCO-listed caravan city with well-preserved earthen architecture
- Chinguetti — 100 km west; former pilgrimage city and ancient centre of Islamic scholarship; UNESCO WHS
- Terjit Oasis — 250 km southwest; rare natural spring in the Sahara; palm groves and cliff pools
Sources
- Richat Structure — Wikipedia
- Matton, G. et al. (2005). “The Richat dome.” Journal of African Earth Sciences.
- NASA Earth Observatory: Eye of Africa
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