THE PALAEOKARSTS IN THE BELGIUM HAINAUT

Carboniferous limestones in the Hainaut province of Belgium are covere d by Mesozoic and Cenozoic sands and clays, except in the deepest vall eys. The landscape is a plateau, but the limestones are intensely kars tified. 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 transfor med by self-volume chemical dissolution. The endokarstic features are dated Early Cretaceous. The rocks-ghosts developed during Aptian and A lbian times before the Cenomanian and Turonian trangressions. The cryp tokarstification happened during the Thanetian. The limestones have a considerable economical importance. Moreover, they constitue one of th e 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.