Cambrian of Ireland

As discussed in Chapter 11 of this Report, some authors have considered that the uppermost part of the Southern Highland Group of the Dalradian in Scotland might be Lower Palaeozoic, possibly Early Cambrian to Early Ordovician. The age of the Irish Dalradian is also not fully clear (Daly 2001). Thus, in Ireland, strata that are clearly Cambrian in age are restricted in outcrop, being confined to some areas of the southeast (Fig. 16) in the Leinster Terrane (Murphy et al. 1991; Woodcock 2000; Holland 2001, 2009). There they comprise the Bray and Cahore Groups and part of the Lower Palaeozoic Ribband Group (Figs 18, 19). In addition, in southernmost Leinster (Fig. 20), palynological studies have now shown that the Cullenstown Formation is Cambrian. In the same area, the Ballycogly Group mylonites, which occur along the boundary between the Leinster Terrane and the Precambrian basement of the Rosslare Terrane, are considered to be Cambrian (Tietzsch-Tyler & Sleeman 1994a) although there is no direct biostratigraphical evidence.