Within the boundaries of the Brecon Beacons National Park there are four separate mountain ranges, including the Black Mountains as well as the Beacons themselves. Most of the area is underlain by old red sandstone, which distinguishes it from the more rugged mountains of North Wales, and several walks explore this terrain of smooth, sweeping grassy uplands and wide, open vistas, including the Brecon Beacons Horseshoe. By extending some walks to the south of the mountains, in the valleys, vale and coast of Glamorgan (including Llantwit Major and the Heritage Coast), the scope of scenic and historic attractions is extended.