Mynydd Myddfai
Mynydd Myddfai is a hill in southwest Wales, about 4.5 miles southeast of Llandovery in Carmarthenshire. It lies within the Brecon Beacons National Park and the Fforest Fawr Geopark. The hill forms a broad ridge with three or four high points. The northwest side drops steeply to the village of Myddfai, while the southern side slopes more gently toward Glasfynydd Forest and the Usk Reservoir.
The top reaches 440 metres and is marked by a trig point at grid reference SN 806297. The rocks are tilted to the southeast in a belt known as the Myddfai Steep Belt. The summit ridge is made of sandstone and mudstone from the Cae'r Mynach Formation. Just southeast is a narrow band called the Tilestones Formation, where old diggings remain from quarrying stone used for roof tiles. Further southeast lies the Raglan Mudstone Formation. These rocks are part of the early Old Red Sandstone from the Silurian period.
To the northwest of the summit are more sandstones, mudstones and siltstones from the Hafod Fawr, Cwm Craig Ddu and Halfway Farm Formations. There are faults that cross the ridge in places. The hill has several ancient cairns and old quarries, and nearby Mynydd Bach Trecastell has Roman remains. In 2007–08, new archaeological finds were made during a trench for a gas pipeline from Milford Haven to Tirley in Gloucestershire.
The hill is open country and freely accessible to walkers. A bridleway runs across it from the Usk Reservoir dam to Cwm yr Olchfa, and another goes southeast to a minor public road at the west end. Coordinates: 51°57′13″N 3°44′19″W.
This page was last edited on 2 February 2026, at 08:05 (CET).