NEW GEOMETRIC ORGANIZATION OF THE CHALK KARST DRAINAGE - THE WEATHERING MESH-NETWORK OF THE MANSONNIERE CAVE SYSTEM (BELLOU-SUR-HUISNE, ORNE, FRANCE)

The Mansonniere karst system presents a labyrinthic network opened on a tectonic pattern near the fault of Belleme. It is the first known ch alk karst system of over 1 km explored galleries in the world. This is also the standard model of a karst system set on a tectonic mesh, dev eloped in a chalk plateau without a detritic cover, showing specific p rocesses. The great karst maze is in fact a poorly drained network but still a functional one which progresses by coalescent weathering fron ts, in the tectonic network. This kind of pattern is specific of a pri mitive degree of karstification.