| Garreg Las | |
|---|---|
| Twyn Swnd | |
Cairns on the summit of Garreg Las |
|
| Elevation | 635 m (2,083 ft) |
| Parent peak | Fan Brycheiniog |
| Listing | Hewitt, Nuttall |
| Translation | blue rock (Welsh) |
| Location | |
| Location | Carmarthenshire, Wales |
| Range | Brecon Beacons |
| OS grid | SN825217 |
Garreg Las is a subsidiary summit of Fan Brycheiniog in the Brecon Beacons National Park in the county of Carmarthenshire, south Wales. Its summit sits towards the northern end of a broad north-south ridge, Esgair Hir ("long ridge"), at 635 metres (2,083 ft) above sea level. The hill is sometimes referred to as Twyn Swnd.[1]
A subsidiary top just over 1 kilometre (0.62 mi) to the north of the main summit is Carreg yr Ogof, whose name ("rock of the cave") reflects its limestone geology. Its top, at 585 metres (1,919 ft) above sea level, is crowned by a trig point.[2]
Contents |
Garreg Las is formed from the Twrch Sandstone, a coarse sandstone (formerly known as the Basal Grit) of the Marros Group (formerly the Millstone Grit Series) which was laid down during the Carboniferous period. Wrapped around its northern and western flanks is a narrow band of Carboniferous Limestone which gives rise to a karst landscape. The Twrch Fechan Fault defines its eastern margin and brings Old Red Sandstone rocks into contact with the limestone on this flank. A number of major shakeholes in the Basal Grit adorn these eastern flanks, one of which, known as 'Pwll Cynrig' is flooded.[3]
On the summit are two prehistoric cairns known as Carnau'r Garreg Las. A further cairn, known as Carn y Gigfran, lies a few hundred metres to the north of Carreg yr Ogof.
The hill is entirely classed as open country and therefore freely available to walkers. A bridleway approaches the hill from Llanddeusant to the north and is followed in part by the Beacons Way which runs from Llangadog to Abergavenny and which continues southwards over the hill.