Description

The monument comprises the remains of Cwm Pit and the head of the Cwm Pit Railway. The site lies near the terminus of the Cyfarthfa Canal built from 1765 to connect a number of surface workings of coal to the furnace complex. The water balance pond at the west end of the site is on the site of a pond shown on the draft Ordnance Survey Map of 1814. This may have been used for scouring. Cwm Pit was not sunk as a deep mine until 1843 when it was a balance pit, eventually reaching a depth of 150 yards. The head of the railway and the site of the pit are bounded on the north side by a massive revetment wall of coursed Pennant sandstone blocks. The raking railway embankment wall rises to a height of about 4m under a heavy flat coping. It kicks out at a point where there are stone steps carried on a pair of semi-circular arches. The revetment wall continues at full height on a stepped base. There are lines of putlog holes, bigger sockets and remains of iron brackets. Within the revetment wall is a semi-circular arch opening into an adit tunnel running back under the site. The base of the tunnel includes a drainage channel. Above and behind the revetment wall are the remains of the colliery buildings. These are reduced and buried except for the base of the engine house chimney made of massive stone blocks with yellow brick details. The end of the railway is easily followed as a modern track. The earliest feature on the site is the water balance or even earlier scouring pond. It was constructed by building a U-shaped earth and stone dam on the hill slope. This still contains a water-filled pond that measures some 40m from NNW to SSE by 22m transversely.

The monument is of national importance for its potential to enhance and illustrate our knowledge of the late 18th and early 19th century coal mining industry. The history of the site dates back into the later 18th century and it demonstrates the technological change from a water balance pit to a deep mine with steam power haulage and drainage. It is the most complete coal mine complex in the Merthyr area. The structures may be expected to contain archaeological information in regard to chronology, building techniques and functional detail.

The scheduled area comprises the remains described and an area around them within which related evidence may be expected to survive. It is irregular and measures up to 350m from NE to SW by up to 130m transversely.

Source: Cadw