Bach

Bach is a small village on the causse whose main claim to fame is the Phosphatieres du Cloup d'Aural, about 2 km outside the village. These are former phosphate mines that tell a story 50 million years old. Natural cavities in the limestone filled with phosphate-rich sediments, which were mined from the mid-19th century to the early 20th century. The excavations uncovered thousands of fossils from a tropical ecosystem that once flourished here, and the abandoned mines have been colonized by unexpected tropical vegetation.

The site is open April to November with guided tours. It's a detour from the GR65, but a fascinating one if you have the time and the inclination to see what the causse looked like when it was a tropical forest.