The Carlingford Lough & Slieve Croob region is one rich in geology, archaeology and history. This guide aims to give an accessible description of the geology of the area, with detailed information on some of the key sites. Where appropriate, the links between the geology, landscape, biodiversity, legend and human settlement in the area over the past millennia are also explored.
The region owes its striking landscape to a combination of the underlying geology and the surface processes that have sculpted these rocks over the millions of years since their formation. The upland areas are all underlain by igneous rocks: Slieve Croob is formed of rocks belonging to the Newry Igneous Complex that was emplaced as the ancient Iapetus Ocean closed; the other areas in the Carlingford Lough region are underlain by granite and gabbro that date back to a period during the opening of the North Atlantic Ocean. The magmas intruded earlier rocks, including sandstone, shale, and limestone, which tell some of the geological history of the region back to 440Ma (million years), a period of time that represents around a tenth of the age of the Earth itself. These rocks have been baked and altered close to their contacts with the igneous intrusions. The ice that covered the region several times in the past 2Ma carved the rocks into corries and Ushaped valleys, and deposited glacial sediment in moraines and drumlins. The weight of the ice also pushed the Earth’s crust downwards; the subsequent rebound of the crust after the melting of the ice led to the formation of raised beaches in this part of Ireland. All of the above are featured in sites described in this guide.