Black Mountain South Top is a top of Black Mountain in the Black Mountains range that spreads across parts of Powys and Monmouthshire in southeast Wales. It is a top which falls exactly on the Welsh-English border, straddling Powys and Herefordshire. The Offa's Dyke Path passes over the summit.
The top is an undistinguished heathery bump on Hatterall Ridge. The summit is marked by a small pile of stones.Nuttall, John & Anne (1999). The Mountains of England & Wales - Volume 1: Wales (2nd edition). Milnthorpe, Cumbria: Cicerone. .
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