Hirfynydd
| Hirfynydd | |
|---|---|
| Highest point | |
| Elevation | 481 m (1,578 ft) |
| Prominence | 246 m (807 ft) |
| Parent peak | Fan Gyhirych |
| Listing | Marilyn |
| Coordinates | 51°45′18″N 3°40′59″W / 51.75503°N 3.68306°WCoordinates: 51°45′18″N 3°40′59″W / 51.75503°N 3.68306°W |
| Naming | |
| Translation | long mountain (Welsh) |
| Geography | |
| Location | Neath Port Talbot, Wales |
| OS grid | SN839076 |
| Topo map | OS Landranger 170 / Explorer 165/166 |
Hirfynydd is a 481-metre-high hill in Neath Port Talbot county borough in South Wales. A Roman road, Sarn Helen, runs along its entire northeast–southwest ridge-line, a route followed by a modern-day byway. To its west is Cwm Dulais and to its southeast is the Vale of Neath. The northern end of the ridge falls away to a broad upland vale containing the Afon Pyrddin and beyond which is the Brecon Beacons National Park.
The larger part of the hill is afforested with conifers. In between the plantations are areas of past or present opencasting for coal.
The upper parts of the hill are formed from the hard-wearing sandstones and intervening mudstones of the Pennant Sandstone. Beneath these are the mudstones and coal seams of the South Wales Coal Measures. All the strata are tilted in a generally southerly direction towards the axis of the South Wales Coalfield syncline though there is significant local variation, due in part to the proximity of the eastern slopes of the hill to the Neath Disturbance.
The Bronze Age Carn Cornel Round Cairn is on the shoulder of hillside, west of the ridge and Roman road. (Location: 51°44′34″N 3°42′55″W / 51.7428°N 3.7152°W, OS grid ref: SN816062.) It is a pile of stones marking a burial, and occupies what appears to be a natural mound. Close by is a boundary stone, suggesting that the site became a historic boundary mark.
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