Located in the Baronnies massif between the Hautes-Alpes and Drôme departments, the Chabre mountain is a bar of Tithonic limestones dating from the Jurassic. Tithonic limestones are pelagic deposits formed by decantation in the open sea. They are rich in ammonite-type fossils and micro-organisms with fragile tests (radiolaria, calpionella). The gray-brown or more or less dark café-au-lait rock in fracture has a light patina and turns cream in some levels of its upper part. It is constituted of the juxtaposition of very fine particles without areas of crystallized calcite. Its bedding is marked with clear benches whose thickness varies between 7.8 and 19.6 in (20 and 50 cm).