Nant Gwys
Encyclopedia
The Nant Gwys is a river flowing off the Black Mountain
in Powys
, Wales
. Its tributaries Gwys Fawr and the Gwys Fach flow south from Banwen Gwyn and Bwlch y Ddeuwynt respectively and join forces to form the Nant Gwys proper which then flows for about 5km / 3mi to its confluence with the Afon Twrch
at Cwm-twrch-Uchaf.
The upper reaches of the river and its tributaries lie within the Brecon Beacons National Park and within Fforest Fawr Geopark
. The river is one of several which run down the southward directed dip-slopes of the Black Mountain passing from the Millstone Grit
outcrop onto the mudstones of the Carboniferous
Coal Measures
.
The name translates from Welsh
as 'sow stream', presumably in reference to the neighbouring Afon Twrch
or 'boar river'.
Black Mountain (range)
The Black Mountain is a mountain range in Mid and West Wales, straddling the county boundary between Carmarthenshire and Powys and forming the westernmost range of the Brecon Beacons National Park. Its highest point is Fan Brycheiniog at 802 metres or 2,631 ft. The Black Mountain also forms a part...
in Powys
Powys
Powys is a local-government county and preserved county in Wales.-Geography:Powys covers the historic counties of Montgomeryshire and Radnorshire, most of Brecknockshire , and a small part of Denbighshire — an area of 5,179 km², making it the largest county in Wales by land area.It is...
, Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
. Its tributaries Gwys Fawr and the Gwys Fach flow south from Banwen Gwyn and Bwlch y Ddeuwynt respectively and join forces to form the Nant Gwys proper which then flows for about 5km / 3mi to its confluence with the Afon Twrch
Afon Twrch
The Afon Twrch is a river which rises in the Black Mountain in south Wales. It forms the boundary between the counties of Powys and Carmarthenshire and, downstream of Ystradowen, between Powys and Neath Port Talbot county borough.The headwaters arise on the southern slopes of Bannau Sir Gaer and...
at Cwm-twrch-Uchaf.
The upper reaches of the river and its tributaries lie within the Brecon Beacons National Park and within Fforest Fawr Geopark
Fforest Fawr Geopark
Fforest Fawr Geopark was the first Geopark to be designated in Wales having gained membership of both the European Geoparks Network and the UNESCO-assisted Global Network of National Geoparks in October 2005. The Geopark aims to promote and support sustainable tourism and other opportunities to...
. The river is one of several which run down the southward directed dip-slopes of the Black Mountain passing from the Millstone Grit
Millstone Grit
Millstone Grit is the name given to any of a number of coarse-grained sandstones of Carboniferous age which occur in the Northern England. The name derives from its use in earlier times as a source of millstones for use principally in watermills...
outcrop onto the mudstones of the Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
Coal Measures
Coal Measures
The Coal Measures is a lithostratigraphical term for the coal-bearing part of the Upper Carboniferous System. It represents the remains of fluvio-deltaic sediment, and consists mainly of clastic rocks interstratified with the beds of coal...
.
The name translates from Welsh
Welsh language
Welsh is a member of the Brythonic branch of the Celtic languages spoken natively in Wales, by some along the Welsh border in England, and in Y Wladfa...
as 'sow stream', presumably in reference to the neighbouring Afon Twrch
Afon Twrch
The Afon Twrch is a river which rises in the Black Mountain in south Wales. It forms the boundary between the counties of Powys and Carmarthenshire and, downstream of Ystradowen, between Powys and Neath Port Talbot county borough.The headwaters arise on the southern slopes of Bannau Sir Gaer and...
or 'boar river'.