The Industrial archaeology of Cwm Twrch by Dilys Powell


Cwm Twrch and its tributary streams dissect the south slope of the Black Mountains, and form some distance from the extreme south-west boundary between the counties of Brecknock and Carmarthen. The area's post-medieval history reflects mixing of the rural, Black Mountains population, with people from the industrialised valleys, of which the area now arguably forms a socio-economic component. As part of the Brecon Beacons National Park, today the upper part of the valley (the main subject of this study) enjoy some measure of environmental protection. The landscape has, nevertheless, suffered severely from pressures of afforestation and recent opencast coal exploitation, economic forces which remain threats to this industrial heritage landscape.

The study which follows was undertaken as part of a countryside management course at the Normal College, Bangor, in 1984, and comprises investigations of both historical sources (part 1), and a field survey of the industrial archaeology (part 2).

Part 1: Historical

Limestone quarrying

In south Wales, lime was originally used for agricultural purposes (Moore-Colyer, this volume, Chapter 5). In Cwm Twrch, farmers collected lime after the harvest. They would take their donkeys or ponies to outcropping coal seams on the valley sides of the Lower Twrch, then carry the coal across the moorland to Blaen Llynfell, where it was used to burn limestone which outcrops there. This was then brought down in panniers and spread onto the enclosed land (Owen et al 1935, 18). By the nineteenth century, improved farming methods had increased the demand for lime which resulted in building small stone kilns which are now commonly found in areas close to limestone outcrops. The main lime burning centres, such as Llandybie, were generally easily accessible and supplied lime to a wide area. The Henllys site in Cwm Twrch, with its bank of five kilns, is unusual in that it is relatively remote and inaccessible from the agriculturally dominated areas of rural Carmarthenshire. The development of lime burning on such a large scale at Henllys is the result of an expanding iron industry along the northern rim of the coalfield during the nineteenth century. Limestone from Henllys was also taken to the ironworks at Ynyscedwyn where it was used as a flux in the furnaces. Limestone quarries were opened on the Black Mountains in 1883 at Blaen Llynfell by John Hay, then the overseer at the Cwmllynfell works. Scores of workmen lived in tents near the quarry during the week, returning home down the valley at weekends. Quarrying was restricted to the summer months, as the men were unable to endure the harsh conditions during the bleak winter months (Owen 1912).

Lime was originally carried down to the kilns on horses with panniers. In 1884, an incline was constructed by John Hay for the kilns below Gelliau Farm to the mountain ridge. A steam engine at the top of the incline lowered the full trucks and pulled up the empty ones. From the top of the incline, a tramline still contours the hillside to the Blaen Llynfell quarries along which the waggons would have been pulled by horses (Owen1912; Owen et al, 1935).

Silica sand workings

Rottenstone and silica sand occur as a result of faulting to the east of the limestone outcrop. This was in great demand at the Landore (Glandwr) works, where it was used for polishing metals (Owen 1912). Later, a silica brickworks was established at Brynhenllys, owned by the Tir Bach Brickworks Company, Ystalyfera (Owen 1912). Before the tramroad was built, men and girls would collect the soft sandstones in baskets from near Ffrydiau Twrch. These were carried on horseback, the gatherers being paid one shilling per journey, three times a day. After 1884, the silica sand was carried down on the incline to the limekilns, and then on the tramroad to the brickworks at Brynhenllys (Owen 1912).

Coal mining

As was the case with limestone quarrying, coal mining began on a small scale, dictated by local needs. It was used for lime burning and as a domestic fuel. It was relatively easy to extract small amounts of coal from the seams outcropping on the valley sides using a method known as 'patchio' (Owen 1912). Mining in its strictest sense did not begin until the late eighteenth century, when a number of local businessmen started to investigate the outcrops Link to previous section and drive levels into the hillside along the line of the two to three underlying seams. The first pit in the area was sunk by Christopher James and R C Aubrey at Cwmllynfell. Here the coal was raised by a water balance system which overbalanced an empty cage at the top while drawing a full cage to the surface (Owen et al 1935). As the Llynfell did not contain sufficient water to operate the balance system during the summer months, a channel known as 'feeder Jams’ was constructed to carry water from the Twrch near Ffrydiau (Thomas 1970, 72). However, mining remained small-scale until 1838. Before that time it had not been possible to use anthracite in the iron industry, but in 1838, George Craneand David Thomas of the Ynyscedwyn works adapted the hot blast process, enabling anthracite to be used in the blast furnace. This greatly increased the local demand for coal and led to an expansion in both the number and scale of the collieries in the valley.


Brynhenllys Colliery was opened in 1792 under the management of five local Welsh businessmen: Enoch Owen Powell, Thomas Powell, Richard Lewis, his son Hywel Lewis and Levi Rees (Thomas 1970, 72; Anon 1901). Locally it was known as Gwaith y Powelliaid. In its heyday 300 workers were employed there extracting 120 tons a day (Evans 1820). After the closure of the Ynyscedwyn Iron Works in 1877 the coal was mainly exported through the port of Swansea.

Operations at Lower Brynhenllys Colliery (SN756 123) were powered by three waterwheels, turned by water from leats. The uppermost feeder was tapped from just below the weir, opposite Upper Brynhenllys Colliery. By taking the water supply from higher up the valley, a fall of 10-20 feet (3-6 m) could be obtained, giving sufficient power to rotate the large wooden waterwheels. These in turn operated the winding engine, screening machinery and the beam pump which drained the mine (Thomas 1970, 75).Nothing remains of either the waterwheels or their associated machinery. The leat can, however, be traced from the weir, following a course roughly parallel to the tramroad. This feeder also turned the wheel which operated the machinery at the silica brickworks. These were situated just above Lower Brynhenllys Colliery, to the south of the present road bridge.

Upper Brynhenllys

On a raised bank, close to the weir, lie the remains of the surface buildings and machinery of Upper Brynhenllys Colliery, which was opened in order to save on haulage from the extremities of the lower colliery (Evans 1890). This colliery also operated on water power until its closure at the turn of the century. The line of the leat can still be followed, being indicated by a line of iron stakes which once held the wooden trough in position. The waterwheel drove the winding engine which brought the coal to the surface from the main slant and also the pump which drove water out of the mine.


Originally, coal at Henllys was extracted almost exclusively for use in the limekilns under the auspices of the Black Mountain Silica Sand, Lime, Brick and Colliery Co Ltd, owned by John Hay. However, production of lime ceased in the late 1880s, as a result of the migration of the iron industry towards the coast, since local iron ore resources had been exhausted and the industry became dependent on imported supplies. After a period of inactivity, the concern was sold in 1898 to the Black Mountain Anthracite Co, which opened Henllys Vale Colliery, near the end of John Hay's incline. Unlike earlier pits, power to haul coal to the surface was provided by a coal-fired steam engine. The engine house chimney still stands. It seems likely that at least in the initial stages of development water power was used to drive coal-sorting screens. There then followed a period of prosperity, the work force rising to 141 in 1904. However, the profitability of the company soon declined so rapidly that it was offered for auction in 1906. The sale included the colliery, silica and limestone quarries, mineral rights over 492.5 acres (c 200 ha), buildings, fixed and loose plant, machinery, railway sidings, stocks, stores and effects. Bids did not reach a realistic level, and the concern was withdrawn from the auction at £ 5,500. The colliery lay idle for a while, then was restarted by a new company, the New Henllys Anthracite Co Ltd, to be worked until the First World War, which effectively withdrew the labour force, and forced the mine to remain idle for the duration of hostilities. In the event, it proved impractical to recommence operations after the War and the mine was finally abandoned in 1918.

Figure 24 Henllys Colliery 1905: leats and tramroads of Lower Cwm Twrch (from OS 25-inch plan)

Part 2: Industrial archaeology: a survey of existing structures at Cwm Twrch (Fig 24)


The best preserved relics are found at Henllys.

Limekilns (SN 7627 1378). Limekilns are arguably the most important feature of the site, being unique in their state of preservation and their remote location, away from major transport routes. It consists of five enormous rubble-choked kilns which are structurally sound. The bank of  kilns was built into a steep slope, probably partly artificial, for top-loading. The kilns appear to have been constructed in two phases. The northern three kilns (one of which has been blocked off) have tall, stone-faced arches, the passages having been extended by the addition of a second facing wall. Their interior is also of stone. The later kilns are better preserved and retain their inner brick walls and tapping arches. The circular kilns have a brick lining above square bases.

Chimney (SN 7624 1378). The chimney is circular and of red brick, rising to some 30.5 m above its octagonal base and capped by a now incomplete ornamental corbell. There is an archway on the southern side of the base. Dart of which has now were demolished sometime in the 1950s. The suggestion has been forwarded that it acted as a ventilation shaft for underground workings, despite the conflicting evidence of coal and ash found at the base. However, local people say that the chimney was once attached to an engine house. Some sources suggest that this steam engine worked the incline, but this is unlikely as the remains of an engine house and small brick chimney are to be found at the top of the incline. Old maps (OS 25-inch 1905) show that the engine must have been used for hauling coal to the surface from Henllys Slant. The impressive size of the chimney is the result of its location within the confines of a narrow valley. It had to be constructed sufficiently tall to allow the smoke to escape.

Masonry Pylons (SN 7623 1383). Beyond the kilns are the remains of three or four stone-built towers which may have carried an aqueduct, As it is not possible to follow the line taken by the associated leat, their purpose is not yet clear.

henllys Slant (SN 7617 1364). The stone-lined entrance to Henllys Slant is still visible, partially hidden by debris, which has fallen from above.

Screening wall (SN 7619 1361). The entrance to the colliery is dominated by a large flat area surrounded by ‘the imposing screen wall. After being hauled up the slant by steam engine, coal was taken to the top of the screen wall by truck and then poured down the chute onto conveyor belts. After sorting, it was loaded into trucks and taken down the valley on the tramline. The screens were operated by water power, at least in the initial stages of development. Water was taken from a weir at (SN 7632 1388), via a stone-lined leat, to a wheelpit at the eastern end of the screening wall. A shallow depression marks the former channel, which returned the water back to the river.


Little of interest is now visible at Upper Brynhenllys. Even the course of the leat which fed the large wooden water wheel is not readily discernible, being marked at best by a line of iron pegs, which once held the wooden trough in place. The most notable feature of the valley below Henllys is the leat which was tapped just below the weir, I near the remains of Upper Brynhenllys Colliery. It has a rough concrete retaining wall, emphasising just how recently water had to be relied upon as a source of power. The regulating weir lies a short distance downstream. From this water level built up on the river it would overflow into! the leat, the course of which can still be followed downstream for a considerable distance. The leat is bridged about 300 m from its source by a masonry structure, vertical on its upstream side, but with supporting buttresses on the downstream side. Between each pair of buttresses is a wooden lintel, approximately one foot (0.3 m) collapsed. the chimney lining has deteriorated and loose yellowish bricks lie inside on a basal fill of coal, dust, and ash. The purpose of the chimney is not clear from structural evidence as the surrounding buildings off the ground, below which the water would have been channelled. Its function is not yet clearly understood. Some 50 m north of the road-bridge, the route of the leat becomes indistinct. Originally, the water split into two channels here. One branch was conduited under the tramline and then followed it down to Lower Brynhenllys Colliery; the other was taken by aqueduct some 20 m to the brickworks. Any remains of the aqueduct system still surviving in situ, will now be buried below the spoil.

Brynhenllys Tramroad

In addition to the tramroad built to carry silica sand down from the Black Mountain quarries to the brickworks, a second tramroad was built at a higher level, to transport coal from Upper Brynhenllys Colliery. Although the two tramroads are parallel for much of their course to the county road from Upper Brynhenllys, the gradient on the upper tramroad is less. In places the side of the higher track is held in place by railway sleepers and iron stakes, but elsewhere the height differential is so great that a retaining wall had to be built. Within the wall is an interesting feature which has proved to be totally inexplicable. An oven-like structure, some 0.75 m wide going back about 2 m, has been built into the retaining wall. The sides and roof are well constructed in stone but there is no back as such, the tramline infill being visible. There are small openings on either side which appear to have no connection to the central cavity.


industrial landscape through routine historical research. Furthermore, systematic attempts to correlate fieldwork observations with both manuscript and published sources have resulted in clear explanations of the functions of otherwise potentially inexplicable features on the ground, giving some idea of the area's economic activity in its heyday. Today the landscape of Cwm Torch is under great pressure from proposals to work opencast coal seams. Although the intended area of opencasting lies to the east of most features described here, this investigation illustrates that a valley such as this, still endowed with recognisable abandoned plant, could be extremely vulnerable to future economic activity. Should further applications for open cast development be forthcoming in Cwm Twrch, this historically interesting industrial landscape, currently unprotected by Statute, will require careful monitoring if the industrial community of south Wales is not to lose further important heritage sites.


Evans, W J, 1890, Hanes Cwmtwrch a Cwm-Uynfell, Cwmtwrch

Owen, J, 1912 Cyflwynedig i Gystadleuaeth,unpubl MS, May 18th 1912

Owen, J Dyfnallt, Jones, J D, and Davies, W D, 1935 Hanes Eglwys Cwmllynfell

Thomas, W G, 1970 'A study of some remains of past mining activity in the Upper Tawe Valleys',

Brycheiniog, 14, 67–78 HMSO, 1930 Catalogue of plans of abandoned mines, Vol 4, London: HMSO

It has been found possible to greatly enhance the outcome of a local area study of a neglected derelict


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