The Schwarzwald (Black Forrest) is a mountain ridge in the southwestern part of Germany. It runs from north to south, about 180 km long and 50 km wide. The highest peak is the Feldberg, 1,493 m asl. To the east the South German Scarplands follows, especially the Schwäbische Alb. To the west the Rheingraben (Rhine valley or Rhine graben) runs parallel to the Black Forrest.
The rocks of the Black Forest originate from the Precambrian and Late Paleozoic and were first deformed in a Paleozoic orogeny. They were again folded and metamorphized during the Variscan orogeny. During the Carbon, magma intruded from below, forming mostly acidic plutonites. Those are the basis for the long mining history of the Black Forest. Heated by the hot magma, the groundwater percolated in cracks, dissolving and precipitating numerous minerals and ores. As a result many veins were formed, filled with lead, zinc, silver and uranium ores.
Most of the Black Forest is covered by crystalline and metamorphic rocks, which are not soluble. Thus, there is almost no karst in this area, except a small area at the southern slopes. Jurassic and Triassic limestones form a sort of escarpment, as a result of the uplift. In the center the uplift was much higher and all the younger sediments were removed and the hard and old rocks form the central Black forest. To the south there was no uplift, and the limestones are covered by younger sediments. But here, with moderate uplift, the younger sediments are eroded and the limestone has reached the surface. The caves in this area are draining to the Rhine in the south.