River Neath

River Neath (Welsh: 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 Bay.

Course

Upper tributaries

The rivers Nedd Fechan, Mellte and Hepste rise in south Powys on the southern slopes of Fforest Fawr. This headwater area is formed from Old Red Sandstone. Each then crosses a band of Carboniferous Limestone before traversing country formed by interlayered sandstones and shales traditionally referred to as the Millstone Grit. Within the limestone belt, short sections of each river flow underground, though that of the Hepste also flows at the surface during periods of particularly wet weather.

The steep descent of these rivers towards the Vale of Neath, and also of the Afon Pyrddin and Afon Sychryd, tributaries of the Nedd Fechan and Afon Mellte respectively, involves the development of a number of waterfalls over resistant bands of sandstone within the Millstone Grit. This is the core of an area which has come to be known as Waterfall Country (Welsh: Bro'r Sgydau).

Main river

The Mellte and the Nedd Fechan converge at Pontneddfechan, from which point the combined waters are known as the River Neath. It flows past Glynneath and on through the Vale of Neath, a long straight valley excavated along the Neath Disturbance by a glacier into Coal Measures rocks during a series of ice ages. Downstream of Pontneddfechan the river has few significant tributaries; the largest is the River Dulais which has its source north of Seven Sisters.