Western Ireland

The Carboniferous rocks of western Ireland extend from the Ox Mountains in south Co. Mayo, south to Galway Bay, east to the western margin of the Dublin Basin Co. Roscommon (Chapter 21) and west to Clew Bay and Clare Island (Figure 19.1). Tournaisian rocks of mostly continental or marginal marine facies, Visean rocks of mostly marine limestone, and Namurian predominantly marine and fluviodeltaic siliciclastic rocks crop out in the region, the entire succession belonging to the Mississippian Subsystem. In western Ireland, late Tournaisian and Visean (Chadian- Asbian) aged shelf limestones occur within structurally controlled basins, many of which are extensions of structures in the adjacent northwest region (see Chapter 19). In the Castlebar area of south Co. Mayo, the Castlebar Syncline represents a southwest extension of the Ballymote Syncline, bounded to the north by the Ox Mountains Inlier and to the south by the Belhavel Fault (Long et al. 2004).