|Elevation||811 m (2,661 ft)|
|Prominence||622 m (2,041 ft)|
|Parent peak||Pen y Fan|
|Listing||Marilyn, Hewitt, Nuttall|
|English translation||small moor|
|Language of name||Welsh|
|Pronunciation||Welsh: [ˈwɑin ˈvɑːx]|
|Location||Black Mountains, South Wales|
|Topo map||OS Landranger 161|
|Listed summits of Waun Fach|
|Pen y Gadair Fawr||800 metres (2,625 ft)||Hewitt, Nuttall|
|Pen Allt-mawr||720 metres (2,362 ft)||Hewitt, Nuttall|
|Rhos Dirion||713 metres (2,339 ft)||sub Hewitt, Nuttall|
|Pen Cerrig-calch||701 metres (2,300 ft)||Hewitt, Nuttall|
|Twmpa||690 metres (2,264 ft)||Hewitt, Nuttall|
|Chwarel y Fan||679 metres (2,228 ft)||Hewitt, Nuttall|
|Mynydd Llysiau||663 metres (2,175 ft)||Hewitt, Nuttall|
Waun Fach is, with a summit height of 811 metres (2,661 ft), the highest mountain in the Black Mountains in south-eastern Wales. It is one of the three Marilyns over 600m that make up the range, the others being Black Mountain and Mynydd Troed. To the north Rhos Fawr and the Radnor Forest can be seen. It is the second highest mountain in Britain south of Snowdonia (after Pen y Fan). It is situated at the head of the Grwyne Fechan valley, above and to the west of the Grwyne Fawr reservoir . It has an undistinguished (and almost indistinguishable ) rounded summit . The nearby tops on the ridge, Pen Trumau and Pen y Gadair Fawr , although lower, are very much more recognisable.
The summit and upper slopes of Waun Fach are formed from the Early Devonian Epoch sandstones of the Brownstones Formation, a division of the Old Red Sandstone. Beneath these and forming the lower slopes are the sandstones of the Senni Formation (traditionally the Senni Beds). Mudstone layers within these sandstones are more readily eroded and have given rise to the stepped appearance of parts of the mountain. No rocks are exposed around its summit as this is covered by a thick layer of peat which has accumulated in the postglacial period, though is much reduced through erosion in recent decades.
The hill is wholly within land mapped under the Countryside and Rights of Way Act 2000 as open country and hence is legally available to walkers despite there being no public rights of way leading to it. Mountain bikers and horseriders can follow the bridleways which lead to the 617m high col south of Pen Trumau but have no legal access to the hill itself. The paths approaching from the north and west have been repaired and improved by the Brecon Beacons National Park Authority, most recently through the Black Mountains Land Use Partnership in recent years, having previously become particularly damaged by use.
- Nuttall, John & Anne (1999). The Mountains of England & Wales - Volume 1: Wales (2nd edition ed.). Milnthorpe, Cumbria: Cicerone. ISBN 1-85284-304-7.
- "England and Wales sheet 214 'Talgarth'". Maps portal. British Geological Survey. Retrieved 17 May 2020.
- "Autumn airlifts". Black Mountains Land use Partnership. BMLUP. Retrieved 17 May 2020.
- Computer generated summit panoramas Waun Fach Index
- www.geograph.co.uk : photos of Waun Fach and surrounding area