Three Rock

Three Rock Mountain (Irish: Binn Trí Charraig;archaic: Sliabh Ruadh) is a mountain in Dún Laoghaire–Rathdown county in Ireland. It is 444 metres (1,457 feet) high and forms part of the group of hills in the Dublin Mountains which comprises Two Rock, Three Rock, Kilmashogue and Tibradden Mountains. The mountain takes its name from the three groups of granite rocks at the summit. It was once believed that these features were man-made: for instance, Gabriel Beranger wrote of them in 1780, "I take them to be altars upon which sacrifices were offered […] the regularity which is observed in piling them convinces me they are the work of man, as they could not grow in that position". In fact, the three outcrops are tors: natural geological features produced by the gradual process of weathering. Today, the summit is dominated by the many radio masts and towers that use the site to broadcast their signals across the Dublin area below. The forestry plantations on the slopes consist mainly of Sitka spruce, Japanese larch, Scots pine, Monterey pine and lodgepole pine.