The Twrch Sandstone Formation gives rise to numerous positive landscape features such as Carreg Dwfn, Tair Carn Uchaf, Gwaun Cefnygarreg in the west of the Brecon Beacons National Park and the plateau surfaces of Mynydd Llangatwg and Mynydd Llangynidr in the east. Faulted blocks of the Twrch Sandstone and Bishopston Mudstone formations are responsible for much of the dramatic scenery within the national park's Waterfall Country.