Two kilometers south of LUC EN DIOIS, in the direction of the Col de Cabre, visitors can only be surprised by the gigantic and chaotic heap of boulders available to them. This is the Claps website. Patois Clapas, heap of stones. In 1442, a base detached from the southern flank of the Pic de Luc. Sliding, it struck a limestone spur downstream, divided, broke into huge blocks and crossed the Drôme at two points. Thus was formed upstream the Grand Lac (about 5 km long) and downstream, the Petit Lac.