English: Aerial of the swabian volcano, “Randecker Maar”. The visible rest of a crater with ca. 1200m is the largest of all extinct Miocene volcanoes of the “Urach-Kirchheimer Vulkangebiet” (Swabian Volcanoes). The crater is a result of phreatomagmatic eruptions. After all available water was evaporated and volcanic activity attenuated, the crater slowly filled with water to become a maar. However, by continual erosion the Swabian Alb’s cuesta got closer and closer to the volcanoes crater; the crater was finally cut, all water ran out. The maar’s muddy floor caught and excellently preserved many examples of fauna and flora, which are now exhibited as valuable fossiles in the Nature Museum of Stuttgart.
The cuesta of the Middle Swabian Alb, well visible in the back, is heavily eroded and dissected by tributaries of the Neckar. The lines of trees in the crater indicate rivulets, whose springs emerge from the impermeable volcanic rocks below. The swampy surface and the assembly of trees on the images’ left is the rest of the only raised bog of the Swabian Alb. This wetland, strictly protected as an important habitat, developed in late Pleistocene on impermeable rock of another volcano.