Black Mountains

Black Mountains, range of mountains in the Welsh counties of Powys and Gwent, and the English county of Herefordshire. The Welsh area is within the Brecon Beacons National Park. Covering about 210 sq km (80 sq mi), the Black Mountains are separated from the Brecon Beacons to the west by the River Usk and the lake of Llangorse; to the north they are bounded by the valley of the River Wye, to the east by the Golden Valley, through which flows the River Dore, and to the south by the town of Abergavenny.

Formed of Old Red Sandstone, their covering of gorse and heather gives them a perpetually dark appearance. They lie in a series of parallel ridges running north-west to south-east and cut by several streams, including Grwyne Fawr and Grwyne Fechan on the Welsh side, and Escley Brook and the River Mannow in England. The highest points are on Gader Ridge, in Powys, rising to 811 m (2,660 ft) on Waun Fach and 800 m (2,624 ft) on Pen-y-Gader Fawr. The principal industries of the valleys are dairy and sheep farming, and tourism. The line of Offa's Dyke, the late 8th-century earthwork separating Wales from the English kingdom of Mercia, runs through the Black Mountains more or less along the line of the current border.