It is the southernmost of a group of basins of similar age found along the southwest coast of Norway between Sognefjord and Nordfjord, developed in the hanging-wall of the Nordfjord-Sogn Detachment.

During the later part of the Silurian period, the western margin of the Baltic Plate was affected by the main collisional event of the Caledonian orogeny, known as the Scandian phase.

When they were first described in 1926, they were interpreted as small thrust sheets involving the emplacement of slices of the underlying upper allochthon rocks beneath the basal unconformity into the conglomerate sequence.

Later investigations failed to find any evidence for tectonic contacts at the base of the lenses and one large body of monomict brecciated gabbro was interpreted as a debris flow.

[2] The conglomerates show evidence of very low-grade metamorphism with recognition of an assemblage of authigenic minerals that indicate temperatures in the range 230–330°C, consistent with maximum burial of up to 13 km.

The basin is cut by a prominent series of nearly north–south trending faults that are interpreted to be of latest Paleozoic to Mesozoic age, associated with west–east extension in the North Sea rift that began during the Permo-Triassic.