Small dry valley "Wiesental", east of Undingen (Sonnenbühl), Middle Swabian Kuppenalb. The huge limestone mound in the back is a protected Naturdenkmal, "Kalkstein Südwest". The valley Wiesental flows into a 10,5 km long dry valley, of which the middle section is called "Großes Rinnental". Topology, elevation and old fluvial terraces, documented by Thekla Abel 2003, allow the reconstruction of a pliocene-pleistocene Ur-Erpf, which flowed into an de:Urlauchert. As the contemporary surface water Erpf is only 2,8 km, the rivulet obviously has a length of only one-fifth of its Ur-Erpf.