A hardground on a calcareous tempestite in the Kalkrieser Berg, Lower Saxony.

The tempestite origin of the upper part of the Zwischenbank (Mittelkimmeridge VII, Upper Jurassic) in the Kalkrieser Berg (Southwestern Lower Saxony) is explained by means of microfacial, paleontological and sedimentological analyses. At the top of the limestone, a hard ground was formed and, at a later stage, exposed by erosion and then colonized; its environment was shallow marine nearshore. This is the first description of the origin of a German Jurassic hard ground s.s. and an Upper Jurassic calcareous tempestite.