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