(Rheinisches Schiefergebirge), mountains in the Federal Republic of Germany and, partially, in Belgium, France, and Luxembourg; situated on both banks of the middle course of the Rhine River. Length, approximately 400 km; elevations, to 880 m (Mount Grosser Feldberg).
The Rhenish Slate Mountains are composed primarily of schists and quartzites. There also are sandstones and limestones; basaltic volcanic domes are encountered. The individual massifs are separated by the deep and, in some places, gorgelike valleys of the Rhine, Mosel, Lahn, Nahe, and other rivers. They have flattened peaks, above which rise for 300–400 m ranges with numerus volcanic cones and maars (Ardennes, Eifel, Sauerland, Hunsrück, Westerwald). The slopes are covered with sparse spruce, oak, and beech forests, and there are marshes and wastelands on the peaks. The terraces of the river valleys and the lower sections of the slopes—primarily those with a southern exposure—are under cultivation (wheat, sugar beets, grapes). There is cattle and sheep raising. The Ruhr, a coal-mining region, is situated in the northern piedmont trough of the mountains.