extensive mountain range in County Wicklow, Ireland, forming part of the Leinster Chain. The mountain area comprises a vast anticline (upwarp of rock strata), with granite exposed at the centre, and also slates and sandstones. Igneous intrusions form the Little Sugar Loaf (1,123 ft 【342 m】) and the Great Sugar Loaf (1,654 ft 【504 m】). The main summits of the range rise over 2,000 ft and consist of smoothly rounded granite hills, but the highest, Lugnaquillia (3,039 ft 【926 m】), is capped with hard mica-schist rocks. There are many fine valleys in the range, including Glenmacnass, Glendasan, Glendalough, Glencree, and those of the Avonmore, Avoca, Aughrim, and Liffey rivers.