Camille Ek

Polyphase karst system in Cretaceous chalk and calcarenite of the Belgian-Dutch border

Along the Belgian-Dutch border, underground and surface quarries dug in Cretaceous calcarenite and chalk intersect many karst features as well as deep large nodes of weathered rock. Their observation allows the reconstruction of the genesis of an original karst system resulting from the merging of initially independent endokarsts and exokarsts. Deep weathering has developed within the Cretaceous formations, creating nodes of weathered chalk and closed cavities. These phenomena are expanded over time and can form interconnected voids. Near the surface, solution pipes are generated under the coarsest deposits of a fluvial terrace capping the Cretaceous formations. These pipes develop vertically and may be related to the progressive lowering of the water table in connection with the incision of the Meuse valley. Some of these phenomena cut up the older endokarsts and organize complex systems of out-flow within the chalk.

Karstic Systems in Eastern Belgium: Remouchamps and Noû Bleû

Belgium is characterised by a wide variety of rocks, including carbonate formations, which are significantly represented in eastern Belgium. Among those formations, Devonian and Carboniferous carbonates display the most developed karstic features, as illustrated by the two cave systems presented in this chapter. Although both systems are water caves, they differ in many ways. The Remouchamps Cave, developed in the Upper Devonian limestones, is a touristic cave, while the Nou Bleu Cave, developed in the Carboniferous carbonates, is a brand new discovery still under exploration. The two systems are of scientific interest and contain many deposits (speleothems and detrital sediments) providing records of past environmental changes and paleoclimates. Beside the Quaternary dynamics, the present-day dynamics can be highlighted within the karstic basins that encompass the two cave systems. The generation or reactivation of sinkholes and swallow holes is often favoured or triggered by human activity. Furthermore, the two basins offer several good examples of human interaction with karst environments, not only in terms of karstic constraints for humans but also as a resource that must be preserved.