A collapse in the limestone sea
The Gouffre de Padirac is a vertical gateway into a hidden hydrological network. The chasm itself, a vast hole 35 meters in diameter, is the result of a collapsed ceiling of a much larger, ancient cavern. This event, which occurred several hundred thousand years ago, exposed a section of a river system that had been chemically and mechanically carving its way through Jurassic limestone for one to two million years. The surrounding area, the Causse de Gramat, is a classic example of karst terrain. This type of topography forms when water, made slightly acidic by atmospheric carbon dioxide, dissolves soluble bedrock like the limestone that formed here 170 million years ago when the region was a shallow sea.
The process began with water infiltrating faults in the limestone plateau. Over millennia, this persistent erosion created a vast network of subterranean galleries. The Padirac River flows at the bottom of the chasm, 103 meters below the surface. Speleologists have so far mapped more than 42 kilometers of these passages, but only a fraction is open to visitors. The initial descent brings you to the level of the river, where the year-round temperature remains a constant 13°C.
The Grand Dome and the Giant Stalactite
The public tour begins with a boat ride along the Rivière Plane (the Flat River). The path leads to chambers of immense scale, sculpted entirely by water. One of the most significant features is the Salle du Grand Dôme (Great Dome Hall). The ceiling of this chamber reaches a height of 94 meters, a space large enough to contain the cathedral of Notre-Dame de Paris.
Within this chamber and others, calcite-laden water dripping from the ceiling has formed a vast array of speleothems (cave formations). The most famous of these is the Grande Pendeloque, a stalactite measuring 60 meters in length that hangs over a body of water called the Lac de la Pluie (Lake of Rain). This lake is fed by water seeping through the rock from the surface. Other formations include the "Pile d'Assiettes" (Stack of Plates), formed by calcite crystals building upon one another over centuries. The cave system has a unique biodiversity, including the tiny crustacean Niphargus and the aquatic snail Bythinella padiraci, species adapted to this subterranean world.