
It was at the end of the primary era and the Permian era 250 million years ago that these vast red lands were born. The erosion of a very ancient crystalline mountain range led to fine silt mixed with volcanic ash being deposited on a flood plain. Pressure and heat transformed this accumulation of sediment into pelite. Their red-wine colour is the result of oxidation of the iron that they contain. Nine hundred metres of deposits are visible below Cime du Barrot.