Most karst landforms in Ireland are found in the West of Ireland, where Carboniferous limestone outcrops cover wide areas. The Sligo/Fermanagh Karst Area is also known as north-western plateau karst. It extends over the Counties Sligo, Leitrim, Cavan, and Fermanagh. The dissected plateau has a cap of shale and sandstone, with karstified limestone below. There are caves and potholes, most of them at the sides of the valleys, which are often glacially deepened.