The Ordovician successions of the Oslo Region, Norway

The Ordovician successions of the Oslo Region are subdivided in terms of a modem lithostratigraphical scheme. Twenty-nine formations are defined; same of which are subdivided into stratigraphical or geographical members. Type localities (including hypostratotypes) are designated and many illustrated by measured sections. Provisional correlations with the standard British and the Baltic chronostratigraphical schemes are made but highlight the lack of good biostratigraphical controls at several levels. The Tremadoc to Llanvirn lithostratigraphy shows considerable uniformity over the Oslo Region but the remainder of the Ordovician shows same marked lithofacies contrasts between, and even within, districts.