The Janusfjellet Subgroup was formed under shallow marine shelf conditions dominated by sedimentation of clay, but silt and sand also accumulated in significant amounts. The sand bodies recognized in the Agardhfjellet Formation (Bathonian-B) are redeposition of sediments originating from earlier deltaic/coastal progradation. The Rurikfjellet Formation (Berriasian-Hauterivian) reveals an upwards increasing sand content reflecting built-out of a delta system. The prodeltaic material was partly reworked by storm currents. The shales of the Agardhfjellet Formation were in part deposited under oxygen-depleted conditions.