Nedd Fechan

The Nedd Fechan forming the county border north of Pontneddfechan: Glamorganshire on the left bank, Brecknockshire on the right

The Nedd Fechan is a river in Brecknockshire. It rises on the eastern slopes of Fan Gyhirych in the Fforest Fawr section of the Brecon Beacons National Park and flows south for seven miles to join with the River Mellte at Pontneddfechan, their combined waters continuing as the River Neath to the sea near Swansea. The only significant tributary of the Nedd Fechan is the River Pyrddin which joins it at Pwll Du ('the black pool'). The river forms the county border with Glamorgan between the Pyrddin and the Mellte.

Geology

The headwaters of the river run over Old Red Sandstone as far as Blaen-nedd-isaf where they encounter the Carboniferous Limestone 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 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 designated for its rare bryophyte flora.

Archaeology

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

References

• Location map: 51°46’16"N, 3°35’43"W