The Bänkerjoch Formation (lower unit of the Keuper Group) underlies the Klettgau Formation. Where the local Keuper aquifer (part of the Klettgau Formation) is absent, the Bänkerjoch Formation is part of the lower confining units (Sections 4.5.3.11, 4.9). The Bänkerjoch Formation was deposited during the Triassic, when Northern Switzerland was located at the southern border of the Central European Basin (Chapter 3). It was deposited in vast sabkha plains with sporadic marine ingressions in an arid climate setting (Dronkert et al. 1990).

Fig. 4‑10:Map of depositional environments during the Middle Triassic (Late Ladinian – Early Carnian) preserved in the Bänkerjoch Formation

Refer to Fig. 4‑3 for a schematic representation of depositional environments. The north arrow refers to present-day geographic north.