The Early Jurassic Staffelegg Formation immediately underlies the Opalinus Clay and is therefore the uppermost stratigraphic element of the lower confining units (Section 4.5.3.9). It corresponds in Northern Switzerland to the Lias Group. The Jurassic was characterised by continued N-S-directed extension during the opening of the Piemont – Liguria Ocean (Chapter 3). The study area was located in a shallow marine epicontinental sea.

Fig. 4‑22:Map of depositional environments during the Early Jurassic (Hettangian to Toarcian) preserved in the Staffelegg Formation

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