Cwm Clydach National Nature Reserve

In a steep gorge west of Abergavenny is a magnificent, ancient beech wood with ferns, mosses, birds and a waterfall.

Cwm Clydach near Brynmawr (not to be confused with RSPB Cwm Clydach near Swansea) is a hidden treasure. As you drive along the busy A465 Heads of the Valleys road through the Clydach Gorge, you may be  unaware of the tranquil glories that can be found just a stone’s throw away. Here, growing on steep slopes, is a magnificent woodland of native beeches. The surrounding landscape has been shaped and gouged by the forces of nature and the Industrial Revolution.

Native beechwoods are rare in Wales. Cwm Clydach’s thick woodlands cloak the slopes almost all the way along one side of the gorge. The woodland is constantly regenerating, the beech trees flourishing in the shallow, stony soil despite the extremely steep slopes. Some are several centuries old, with fantastic roots, clinging like gnarled, multi-fingered hands to the precipitous terrain.

A rare survivor

The Clydach Gorge has a fascinating history. From most parts of the reserve there are views of abandoned tramways, old quarries and industrial settlements. The former railway line along the side of the forge between Abergavenny and Brynmawr is now a cycle path leading into and around the reserve.

During the Industrial Revolution, the trees were cut to provide charcoal for the local ironworks; evidence of charcoal burning can still be seen along some of the paths. So how did the woods manage to survive? Cwm Clydach’s steep topography was its salvation. After their initial exploitation these inaccessible woodlands regenerated and survived.

In the woods

Cwm Clydach is a wonderful place for woodland walks. The reserve is atmospheric throughout the year, but for sheer spectacle, come for the summer or autumn foliage.

The dense canopy of trees creates a shady, secluded environment. Plant life is limited because of the lack of light; the unusual bird’s nest orchid (best seen in June) is one of the few species to prosper. Autumn is the most prolific season, when the glades are filled with a tremendous variety of fungi (almost 400 species discovered so far).

Rare whitebeam trees, distinguished by the white undersides of their leaves in summer and red berries in autumn, grow along the cliffs and old railway cuttings. They occur nowhere else in the world apart from a few other locations in Wales and England.

Birds thrive in these woodlands. Look out for the green or great spotted woodpecker, nuthatch, sparrowhawk and tawny owl. Numerous butterflies and other mini-beasts are also found on the reserve and the list is growing as more and more species are spotted.

Along the riverbank

A walking trail leads along the banks of the River Clydach as it cascades down the gorge. Humid conditions here result in a more lush collection of plants than higher up, such as ramsons and dog’s mercury, together with a great variety of fern and moss. The path’s natural end is at a spectacular series of waterfalls, set in a dark gap.

This riverside walk reveals the reserve’s most substantial evidence of industrial activity. The path follows the line of an old aqueduct that was used to carry water to power the bellows at the Clydach Ironworks. At the first waterfall you can still see the iron fixing bolts in the rock where the water was diverted.

Outside the reserve, downstream at Clydach village, you can visit the ironworks themselves. Substantial remains of blast furnaces, a casting area and wheel pit survive from this important industrial site that employed 1250 men in 1841. Click here to find out more.

A geological cross section

The gorge slices deeply through many layers of rock, revealing the geological evolution of South Wales as a layer of steps. At the bottom of the gorge is old red sandstone, rising to pale grey limestone and then to ironstone and coal measures.

Visiting Cwm Clydach

The reserve is open to the public. Access is free. Much of the terrain is steep and surfaces can be slippery. There are cliffs and a river with waterfalls. The water is deep and fast-flowing in places. You should wear suitable footwear and take care.

How to get there

The reserve is beside the A465, two miles east of Brynmawr, on the Abergavenny to Brynmawr bus route. The easiest access is from the bottom of the gorge. There is also an entry point off the roundabout on the A465 at Brynmawr at the top of the gorge.

Nearest town or village


OS grid reference