Molach, biotope in a depression, western border of an Alb plateau, called „Erkenbrechtsweiler“. There are 355 Miocene volcanoes (Urach-Kirchheimer Vulkangebiet), Middle Swabian Alb. Surface of a rest of a volcano volcanic pipe, style phreatomagmatic eruption. The biotope and the larger depression developed through the sagging (compaction) of welded tuff. Genuine volcanic rock is impermeable for water.