Geology
The Black Forest consists of a cover of sandstone on top of a core of gneiss and granites. Formerly it shared tectonic evolution with the nearby Vosges Mountains. Later during the Middle Eocene a rifting period affected the area and caused formation of the Rhine graben. During the last glacial period of the Würm glaciation, the Black Forest was covered by glaciers; several tarns (or lakes) such as the Mummelsee are remains of this period.
Read more about this topic: Black Forest