The transition from Neoproterozoic glacial to interglacial sedimentation near Hammarnes, East Finnmark, North Norway

A profile through the boundary between the Neoproterozoic Smalfjord (glacial; sensu-lato) and Nyborg (post-glacial) Formations at Hammarnes, East Finnmark, shows lithologies of the two units are intercalated, with rocks diagnostic of the Nyborg Formation (cap-dolostones, red shales) underlying Smalfjord-type clastic sediments (conglomerates, dark grey shales, pale grey sandstones). Since these latter rocks are almost certainly post-glacial, identical rocks underlying the lowest Nyborg-type lithologies must also be post-glacial. Thus the base of the Nyborg Formation cannot be unequivocally taken as the onset of post-glacial sedimentation; a small, but unknown amount of the Smalfjord Formation is probably also of post-glacial age, reflecting localized reworking of older, glacial sediments.