It is considered proven that the Black Forest was heavily glaciated during the peak periods of at least the Riss and Würm glaciations (up to about 10,000 years ago). This glacial geomorphology characterizes almost all of the High Black Forest as well as the main ridge of the Northern Black Forest. Apart from that, it is only discernible from a large number of cirques mainly facing northeast. Especially in this direction snow accumulated on the shaded and leeward slopes of the summit plateau to form short cirque glaciers that made the sides of these funnel-shaped depressions. There are still tarns in some of these old cirques, partly a result of the anthropogenic elevation of the low-side lip of the cirque, such as the Mummelsee, Wildsee, Schurmsee, Glaswaldsee, Buhlbachsee, Nonnenmattweiher, and Feldsee. The Titisee formed as glacial lake behind a glacial moraine.