Where is it? Trou au Natron, Tibesti Massif, Chad. This volcanic caldera, about 3,300 feet wide, is a fascinating site in northern Chad.
From space, this crater looks like a skull, gazing skyward from its floor. But, up close, it appears quite different.
When astronauts captured this image from the International Space Station on February 12, 2023, they revealed a ghostly structure within the caldera. Over time, hundreds of thousands of years ago, a significant eruption created Trou au Natron, also called Doon Orei, which means “big hole” in local language.
This area is part of the Tibesti Massif, a mountain range stretching across Chad and Libya, nestled in the Sahara Desert. The caldera gives a haunting view from above. The white areas you observe come from natron, a naturally occurring compound consisting of sodium carbonate and other minerals. This creates a flaky, cracked surface resembling dry paint.
The features that resemble eye sockets and a nose are actually cinder cones—volcanic hills that form around vents. These cones rise higher than the caldera floor, contributing to that eerie visage. The shadows they cast enhance the skull-like illusion.
Despite its stark, lifeless appearance today, Trou au Natron was once home to a glacial lake. Fossils of marine life, including sea snails and plankton, were found beneath the natron crust, dating back as far as 14,000 years. A 2015 expedition unearthed algal fossils dating even further back, around 120,000 years ago.
Interestingly, while Trou au Natron is currently dormant, it’s near Tarso Toussidé, a large volcanic area with a stratovolcano believed to still have volcanic activity. This shows that while the caldera may be quiet now, the landscape is shaped by its fiery past.
Similar skull-like formations exist elsewhere. For instance, Nicaragua’s Chiltepe Peninsula features calderas that form a landscape reminiscent of Trou au Natron, highlighting how nature often plays tricks with our perceptions.
For more stunning geological insights, check out NASA’s Earth Observatory and the Smithsonian Institution’s Global Volcanism Program for further details on volcanoes and their histories.
