Fig. 1

Map of the North Atlantic Borderlands in their pre-Mesozoic drift positions showing the distribution of Avalonia and other Neoproterozoic peri-Gondwanan terranes (modified from Strachan and Taylor 1990; Nance and Murphy 1994). The portion of Avalonia in Atlantic Canada is identified as West Avalonia, the portion in Britain and Ireland is known as East Avalonia. Only peri-Gondwanan terranes where Cambrian overstep sequences occur are identified (see Theokritoff 1979; Keppie 1985; Murphy et al. 2004; Landing 2005). AB Antigonish Basin, AH Antigonish Highlands, HF Hollow Fault, MB Maritimes Basin, MFZ Minas Fault Zone, SB Stellarton Basin