The Klettgau Formation is a heterogeneous sedimentary succession with prominent lateral facies changes. In the Ergolz Member, channel, overbank and floodplain facies associations alternate laterally. The sandstones show a great variability in terms of composition, degree of diagenesis and porosity. The «channel facies» is incised in, or flanked by, the overbank and floodplain facies. The most typical channel facies was drilled in STA2, but, based on the inferred depositional environment, it is assumed that this facies may potentially occur in all the siting regions. The Gansingen Member decreases in thickness and shows a general facies trend from dolostone to anhydrite from west to east (along the siting regions). The Gruhalde Member exhibits a similar facies in all three siting regions, but the Seebi Member can be defined only in NL and ZNO. The Seebi Member shows a general facies change from west to east (along the siting regions) with both increasing thickness and macroporosity. Partly porous sandstones in the lower part of the Seebi Member and brecciated dolocretes with vugs have only been found in the boreholes of ZNO, and their occurrence seems also to increase towards the east.