At the "Causse Noir", about 15 kilometers east of the town of "Millau", the well known geologic lunapark called "Chaos de Montpellier-le-Vieux" is situated. Here, the rock-formations consist of dolomite. This dolomite is approximately 170 million years old and is heavily fractured. Because of these fractures, the dolomite is visible as single rock-formations.

The rock-formations are given names like "La Chapelle" and "La Cathédrale". Seen from a large distance, the formations indeed look like chapels and cathedrals.