The Lower Allochthon Osen-Røa Nappe Complex in Norway and the Jemtlandian Nappes of Sweden, contain Ordovician limestones shown to be deeper water equivalents of the Huk Formation ( = 'Orthoceras' Limes tone, Orthoceratite Limestone) of the autochthon and younger. They are redefined as the Stein Formation (Arenig-Llanvirn) and the newly named Elvdal Formation (Llandeilo-?Caradoc). The Stein Formation, consisting of the Herram Member and Steinsholmen Member (new name), is 40-50 m thick but thins towards the basin in the west and is replaced by the Ørnberget formation at Etnedal, Norway and the Föllinge Formation west of Andersön-Norderön, Jämtland, Sweden. The Stein Formation contains 2-5 times less magnesium (Mg) than that recorded from the Huk Formation. The Elvdal Formation, estimated to be 14 m thick, is thrust between Precambrian units in central east Norway, south of Lake Femunden. Although lithologically similar to the Stein Formation, its contained conodonts are distinctly younger (P. anserinus Zone). The Stein Formation yields Baltoscandian conodonts together with deeper water elements known from Western Newfoundland and Spitsbergen. The Elvdal Formation contains more than twice the amount of manganese (3000-5000 ppm Mn) recorded from the Stein Formation.

J. A. Rasmussen, Geologisk Institutt, Københavns Universitet, Øster Voldgade 10, 1350 Copenhagen K, Denmark;
D. L. Bruton, Paleontologisk Museum, Universitetet i Oslo, Sars Gate 1, 0562. Oslo 5, Norway.