The Afon Twrch is a river which rises in the Black Mountain in south Wales. It forms the boundary between Powys and Carmarthenshire and, downstream of Ystradowen, between Powys and Neath Port Talbot.
Name
The name derives from
Welsh language / 'river' and / 'boar'. In common with other rivers sharing the same name, it is believed to refer to the burrowing or snouting action of the waters of the river.
[Owen, H.W. & Morgan, R. 2007 'Dictionary of the Place-names of Wales' Gomer Press, Ceredigion] The river has also been associated with the legend of
Twrch Trwyth.
Geography
The headwaters arise on the southern slopes of
Carmarthen Fans (Bannau Sir Gaer) and
Fan Brycheiniog and are soon joined by the waters of the Twrch Fechan. The river flows south-west and then south and finally south-east for about to its
confluence with the
River Tawe at
Ystalyfera. Tributaries include the
Nant Gwys and the
Nant Llynfell.
[Ordnance Survey Explorer map OL12 'Brecon Beacons National Park: western area']
Settlements on the lower section of the river include Ystradowen, Cwm-twrch-uchaf, Cwm-twrch-isaf and Gurnos.
Parts of Cwm Twrch on its Carmarthenshire side are designated as an SSSI because they expose a good example of a boundary between strata.
History
A
colliery was established at Henllys Vale (OS grid ref SN762137) from which tramroads or
waggonway ran down the valley to Cwm-twrch-isaf. A tall brick chimney is among the remains of several buildings associated with the former colliery. A bank of
limekilns is also located at this spot, which can be reached by a walk along the line of the tramway running upstream from Brynhenllys Bridge (OS grid ref SN 756125).
