The Collapsed Shield Volcano
Cirque de Mafate is one of three massive depressions carved into the flanks of Piton des Neiges, a dormant shield volcano that is the highest point on Réunion island at 3,069 meters. The cirque's formation began not with a simple eruption, but with the collapse of the volcano's magma chamber. This created a vast caldera, which was then sculpted over millennia by immense, gravity-driven landslides and the intense erosional force of tropical rainfall. The process has been ongoing since the effusive volcanic activity of Piton des Neiges began to decrease approximately 220,000 years ago.
The result is a dramatic and chaotic landscape enclosed by precipitous cliffs called "remparts," which rise up to 1,600 meters from the valley floor. The cirque itself spans an area of roughly 100 square kilometers. Its geology is laid bare on the cliff faces, where layers of ancient basaltic lava flows, breccias (rock fragments cemented together), and vertical dikes show the internal plumbing of the volcano. The entire structure forms the watershed for the Rivière des Galets, which exits the cirque to the northwest.
An Isolated Human Ecosystem
The extreme topography that makes Mafate a geomorphological feature also created a unique human refuge. The cirque's first permanent inhabitants were "marrons"—enslaved people who escaped from coastal plantations in the 18th and 19th centuries. The inaccessible terrain offered a natural fortress where they could establish a self-sufficient society. Later, after the abolition of slavery in 1848, they were joined by poor white settlers, known as "Petits Blancs," who were also seeking land.
Today, around 700 to 800 residents, the Mafatais, live in about ten small villages called "îlets," located on the few relatively flat plateaus within the cirque. These communities, like La Nouvelle and Marla, exist in isolation. There is no public electrical grid; power comes from solar panels and diesel generators, the fuel for which must be flown in. All supplies, from food to building materials, arrive either by helicopter or on foot, carried along more than 140 kilometers of maintained trails. This enforced simplicity has preserved a unique way of life, the entire area became a designation as a UNESCO World Heritage site in 2010.