The 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 Palaeozoic and were first deformed in a Palaeozoic orogeny. They were again folded and metamorphized during the variszian orogeny. During the Carbon magma intruded from below forming mostliy acidic plutonites. Those are the basis for the long mining history of the Black Forest. Heated by the hot magma, the ground water percolated in cracks, soluting and depositing many different minerals and ores. As a result many many dykes 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 southernslopes. 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.