The Nedd Fechan is a river almost wholly within the county of

Powys Powys (; ) is a county and preserved county in Wales. It is named after the Kingdom of Powys which was a Welsh successor state, petty kingdom and principality that emerged during the Middle Ages following the end of Roman rule in Britain. Geog ...

Wales Wales ( cy, Cymru ) is a country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in ...

, currently administered as part of the unitary authority of

. It rises on the eastern slopes of

Fan Gyhirych Fan Gyhirych is a mountain in the Fforest Fawr section of Brecon Beacons National Park in south Wales. It lies within the county of Breconshire, and administered as part of the unitary authority of Powys. Its highest point at 2379 feet (o ...

in the

Fforest Fawr Fforest Fawr is an extensive upland area in the county of Powys, Wales. Formerly known as the Great Forest of Brecknock in English, it was a royal hunting area for several centuries but is now used primarily for sheep grazing, forestry, water cat ...

section of the

Brecon Beacons National Park The Brecon Beacons National Park ( cy, Parc Cenedlaethol Bannau Brycheiniog) is one of three national parks in Wales, and is centred on the Brecon Beacons range of hills in southern Wales. It includes the Black Mountain ( cy, Y Mynydd Du) i ...

and flows south for 7 miles (12 km) to join with the

Afon Mellte Afon Mellte or the River Mellte is a river in south Wales. It is formed by the confluence of the Afon Llia and the Afon Dringarth. It then flows south through the village of Ystradfellte to Pontneddfechan where it joins with the Nedd Fechan ...

at Pontneddfechan, their combined waters continuing as the

River Neath River Neath ( cy, Afon Nedd) is a river in south Wales running south west from the point at which its headwaters arising in the Brecon Beacons National Park converge to its mouth at Baglan Bay below Briton Ferry on the east side of Swansea Ba ...

(

Welsh Welsh may refer to: Related to Wales * Welsh, referring or related to Wales * Welsh language, a Brittonic Celtic language spoken in Wales * Welsh people People * Welsh (surname) * Sometimes used as a synonym for the ancient Britons (Celtic peop ...

Afon Nedd) to the sea near Swansea. The only significant tributary of the Nedd Fechan is the

Afon Pyrddin The Afon Pyrddin is a river forming a short section of the boundary between the counties of Brecknockshire and Glamorgan in Wales, Great Britain. It also forms a part of the boundary of the Brecon Beacons National Park, and the boundary of the unit ...

which joins it at Pwll Du ar Byrddin ('the black pool of the Pyrddin'). Downstream of this confluence it forms the boundary between Powys to its east and

Neath Port Talbot Neath Port Talbot ( cy, Castell-nedd Port Talbot) is a county borough in the south-west of Wales. Its principal towns are Neath, Port Talbot, Briton Ferry and Pontardawe. The county borough borders Bridgend County Borough and Rhondda Cynon Taf ...

to its west. __TOC__

Geology

The headwaters of the river run over

Old Red Sandstone The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the northeastern seaboard of North America. It also exte ...

as far as Blaen-nedd-isaf where they encounter the

Carboniferous Limestone Carboniferous Limestone is a collective term for the succession of limestones occurring widely throughout Great Britain and Ireland that were deposited during the Dinantian epoch (geology), Epoch of the Carboniferous period (geology), Period. T ...

outcrop. The river then continues through a wooded gorge for the remainder of its course. The section downstream of Pont Rhyd-y-cnau is cut in sandstones and mudstones of the Millstone Grit series. The section between Pont Melin-fach and the confluence of the river with the Afon Pyrddin is perhaps the most dramatic as the river plunges over several falls of which Sgwd Ddwli and Sgwd Pedol are the most acclaimed. Each of the falls is associated with faults bringing harder sandstone beds into contact with the more readily eroded mudstones.

Habitat protection

The entire gorge section of the Nedd Fechan valley is protected as part of a larger site of special scientific interest which also covers neighbouring river gorges. It also forms a part of a larger

special area of conservation A Special Area of Conservation (SAC) is defined in the European Union's Habitats Directive (92/43/EEC), also known as the ''Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora''. They are to protect the 220 habitats and a ...

designated for its rare

bryophyte The Bryophyta s.l. are a proposed taxonomic division containing three groups of non-vascular land plants (embryophytes): the liverworts, hornworts and mosses. Bryophyta s.s. consists of the mosses only. They are characteristically limited in s ...

flora.

Archaeology

Downstream of the Pyrddin confluence is abundant evidence of the former silica rock mining industry. A number of

adit An adit (from Latin ''aditus'', entrance) is an entrance to an underground mine which is horizontal or nearly horizontal, by which the mine can be entered, drained of water, ventilated, and minerals extracted at the lowest convenient level. Adit ...

s are visible on both sides of the river, most of which were served by horse-drawn tramways. The former tramways now provide easy access along this lower section of the gorge.Brecon Beacons National Park website
/ref>

References

{{authority control Fforest Fawr Rivers of the Brecon Beacons National Park Rivers of Neath Port Talbot Rivers of Powys