Abstract:
THE VERCORS: A MASSIF OF MIDDLE ALPINE MOUNTAIN - The Vercors is a forested massif of middle mountain, in the French Northern Prealps. The characteristic of the Vercors massif is the thick and massif urgonian limestones, which underlines a folded structure. The Vercors quickly hold the attention of speleologists, who had put forward the density and diversity of karstic aspects since the beginning of the century. Landforms display glacial karstic landscapes more or less damaged in terms of bio-climatic levels of mounts and depressions landscapes and of deep water gaps, which main flows of the massif are flowing in. The notion of the morphoclimatic heritage applies to the underground karst for which glacial quaternary episodes have been determinant in the large systems genesis (gouffre Berger - Scialet de la Fromagère, Antre des Damnés, Combe de Fer...). The study of underground deposits allows to bring up-to-date various period of karst development; a preglacial stage (e.g. upper levels of Cuves de Sassenage, Gournier, Coufin-Chevaline...). The study of the current dynamic shows that the Vercors as an important karstic ablation, between 120 to 170mm/ky. The karstic dynamic exerts mainly on the superficial slab of the massif (from 80 to 50% of the whole ablation). The Vercors can be considered as the best example of calcareous massif in temperate middle mountains, thanks to the combination of various favourable parameters: pure karst rocks, morpho-climatic episodes not constraining, and a high karstic dynamic.