Definition
This unit has not been described previously and we have identified it with certainty only in the Reinsvoll area of the Toten district. The Reinsvoll Formation is not assigned to any of the groups described herein at this stage, but is provisionally described here in view of its potential regional significance. The Reinsvoll Formation consists of poorly exposed red shales of unknown total thickness. Its basal stratotype is exposed on a farm track between Highway 4 and Berget, on the eastern bank of the Hunselv river in Toten (NN876269). The lower 21 m of the Hunselv section consist of calcareous sandstones with bioclastic interbeds and shaly partings; these beds are assigned to the Bruflat Formation and the upper 10 m of this sequence are reddened. These are overlain by approximately 15 m of monotonous red shales which we here assign to the Reinsvoll Formation, but the nature of the contact with the underlying beds is obscure. Similar red shales have also been seen in trenches dug for a new housing development immediately south of Reinsvoll (NN886279). Loose blocks are also present in drift above a nearby road‑cutting. No definite equivalents of the Reinsvoll Formation have yet been found in Hadeland. In the Hamar and Ringsaker districts the Bruflat Formation is unconformably overlain by rhomb‑porphyry lavas and by the Brumunddalen Sandstone Kiær 1922, Rosendahl 1929) of probable Permo‑Triassic age. The junction, seen at several places on Bjørgeberget (PN0555) is poorly exposed, and the presence of the Reinsvoll Formation there can neither be confirmed nor rejected.
Depositional environments and age of the Reinsvoll Formation are uncertain. Although the formation is certainly younger than the underlying Bruflat Formation, no identifiable fossils have yet been found.