Wikipedia
Rotliegend
The Rotliegend, Rotliegend Group or Rotliegendes is a lithostratigraphic unit (a sequence of rock strata) of latest Carboniferous to Guadalupian (middle Permian) age that is found in the subsurface of large areas in western and central Europe. The Rotliegend mainly consists of sandstone layers. It is usually covered by the Zechstein and lies on top of regionally different formations of late Carboniferous age.
The name Rotliegend has in the past not only been used to address the rock strata themselves, but also the time span in which they were formed (in which case the Rotliegend was considered a series or subsystem of the Permian). This time span corresponds roughly with the length of the Cisuralian epoch.