The Highland Border–Clew Bay–Fair Head–Baie Verte–Brompton Line, which probably marks the Laurentian margin, passes through Achill Island in western Ireland as a zone of ductile transpression within which the Clew Bay Complex and Dalradian Supergroup are juxtaposed. Dextral greenschist facies transpression fabrics in the Clew Bay Complex record the northwest directed emplacement of terranes, bearing high P –low T mineral assemblages, against Laurentia, causing the Dalradian continental margin sediments to be thrust westward. There are significant differences in timing, structural geometry and regional facing between W Ireland and the Scottish Highland Border Zone.