The palaeokarsts in the Belgium Hainaut

Carboniferous limestones in the Hainaut province of Belgium are covered by Mesozoic and Cenozoic sands and clays, except in the deepest valleys. The landscape is a plateau, but the limestones are intensely karstified. The endokarstic features are horizontal galleries that can be seen in the quarries. Cryptokarsts are essentially crypto-dolinas with tertiary filling. ''Rocks-ghosts'' structure are original alteration forms in which the structure of the dinantian massif (stratification, lithologic accidents) is outwardly conserved. But the rock is transformed by self-volume chemical dissolution. The endokarstic features are dated Early Cretaceous. The rocks-ghosts developed during Aptian and Albian times before the Cenomanian and Turonian trangressions. The cryptokarstification happened during the Thanetian. The limestones have a considerable economical importance. Moreover, they constitue one of the most important aquifers in Belgium. The reactivation of the karstic features by pumping can provoke the formation of natural pits. At last, these karstic features are of great scientific interest for research, particulary in paleogeographical reconstructions of the continental environments.