“La Calestienne” is the strip of Devonian limestones which separates the Ardennes from the Famenne and Condroz regions. It contains the most important karstic phenomena in Belgium. The karst system developed over 10 kilometers along the river Lomme (Lhomme) and its main tributary, the Wamme, in the region of Rochefort, illustrates the main characteristics of the Calestienne. The Calestienne around Rochefort is bordered to the northwest by the wide depression of the Famenne shales, the altitude of which oscillates between 150 and 200 meters. In the southeast of this limestone strip, the Ardenne, a region composed of more resistant rocks, rises to altitudes often greater than 400 m. In the landscape, the Calestienne forms a real step at an intermediate altitude. To the Northeast of Rochefort, the limestone strip widens out considerably due to the Gerny anticline.