The Toulourenc, a torrential river on the north side of Mont Ventoux, has its source at the foot of the Château d'Aulan. The river has dug deep gorges in the rock of its bed, sometimes reaching 100 meters.
The marls shape the landscape into soft rock dunes with arid slopes. True witnesses of the Lower Cretaceous period (approximately -135 million years), these Valanginian marls are mostly composed of …