The Southern Permian Basin (SPB) formed a large, elongated saucer-shaped inland depression extending from the UK to Poland and from Belgium to Denmark. During the Middle to early Late Permian the SPB was filled progressively by playa sediments from its centre in northwestern Germany before it was flooded at the onset of the Zechstein. The Netherlands were situated at the southern part of the saline playa lake.

The sediment fill has an onlap configuration upon the underlying Carboniferous and Lower Rotliegend strata. Although regional contour maps suggest a fairly gradual thinning of the Upper Rotliegend interval towards the basin...