Three models are evaluated for restoring basement rocks coring tectonic windows (Window-Basement) in the Scandinavian Caledonides; parautochthonous (Model I) and allochthonous (models II/III), with initial imbrication of the Window-Basement post-dating or pre-dating, respectively, that in the external imbricate zone (Lower Allochthon). In Model I, the Window-Basement comes from the eastern margin of the basin now imbricated into the Lower Allochthon, while in models II/III it comes from the western margin. In Model II, the Window-Basement formed a basement-high between Tonian and Cryogenian sediments imbricated into the Middle and Lower allochthons; in Model III deposition of the Lower Allochthon sediments commenced in Ediacaran times. Balanced cross-sections and branch-line restorations of four transects (Finnmark–Troms, Västerbotten–Nordland, Jämtland–Trøndelag, Telemark–Møre og Romsdal) show similar restored lengths for the models in two transects and longer restorations for models II/III in the other transects. Model I can result in c. 280 km wide gaps in the restored Lower Allochthon, evidence for which is not seen in the sedimentology. The presence of <3 km thick alluvial-fan deposits at the base of the Middle Allochthon indicates proximal, rapidly uplifting basement during Tonian–Cryogenian periods, taken as the origin of the Window-Basement during thrusting in models II/III. Model I requires multiple changes in thrusting-direction and predicts major thrusts or back-thrusts, currently unrecognized, separating parts of the Lower Allochthon; neither are required in models II/III. Metamorphic data are consistent with models II/III. Despite considerable along-strike structural variability in the external Scandinavian Caledonides, models II/III are preferred for the restoration of the Window-Basement.

Dionidid and raphiophorid trilobites are described from the middle Ordovician (Viruan Series) of Jämtland, central Sweden. The family Dionididae is represented by one genus, Dionide Barrande, 1847, and the family Raphiophoridae by five genera, Ampyx Dalman, 1827, Ampyxella Dean, 1960, Ampyxoides Whittington, 1965, Cnemidopyge Whittard, 1955 and Lonchodomas Angelin, 1854. Seven species are described and discussed. Three of these are new: Dionide jemtlandica sp. nov., Ampyxoides minor sp. nov. and Lonchodomas striolatus sp. nov.. The majority of the trilobites described are from the Andersön Shale, equivalent to the H. teretiusculus, N. gracilis and lowermost D. multidens Zones (upper Llanvirn and lower Caradoc), and the Örån Shale, equivalent to the lower D. dingani and the uppermost D. multidens Zones (middle Caradoc). Meraspid and early holaspid material of D. jemtlandica is described.