Clydach Merthyr Colliery

Overview

A drift mine at Craig Cefn Parc on the lower Clydach, opened in 1863 and working the Graigola seam for nearly a century with five to six hundred men. Almost free of gas, it was worked with carbide lamps and had boilers and a smithy underground; coal stopped in 1961, and it was kept open to 1978 to ventilate and drain Graig Merthyr.

History

Clydach Merthyr Colliery, originally the Western Merthyr Slant and known locally as 'Nixon's', stood at Craig Cefn Parc on the lower River Clydach, about eight miles up the Swansea valley. The Clydach Merthyr Company, later the Graigola Merthyr Company, opened the drift in 1863. In 1896 it employed 409 men producing manufacturing coal from the Graigola seam, 498 in 1908, 529 in 1918, 556 in 1923 and 593 in 1945.

The mine was almost free of gas, so carbide lamps were commonly used for light. Unusually it had a blacksmith's shop underground and boilers raising steam for the haulage engines, with a flue along the return airway to a square chimney behind the fan house. Like other Graigola mines it had a very strong sandstone roof, and large areas needed little support. Before it closed it was producing 115,000 tons of saleable coal a year.

The mine stopped producing coal in 1961, but was kept open until 1978 to provide ventilation and pumping for Graig Merthyr Colliery, about three miles to the west.

Geology

The Graigola seam, under a very strong sandstone roof; the Brynwhilach and Swansea Four Feet appear on its later abandonment plans.

Workings

Drift workings in the Graigola, with an underground blacksmith's shop and steam boilers for the haulage engines, their flue running in the return airway to a chimney behind the fan house.

Closure

Coal production stopped in 1961; the mine was kept open until 1978 to ventilate and pump for Graig Merthyr Colliery.

What remains

Unknown.

Redevelopment

Unknown.

Related mines

• Birchrock Colliery — Clydach Merthyr was kept open until 1978 to ventilate and pump for Graig Merthyr.

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• The Clydach Merthyr Company opened the drift in 1863. ¹
• It employed 409 men in 1896 and 593 in 1945, working the Graigola seam. ¹
• The mine was virtually gas free, and carbide lamps were frequently used. ¹
• Five deaths were recorded at Clydach Merthyr in 1900, among them two boy hauliers and a door boy. ²
• Clydach Merthyr's workings in the Swansea Four Feet were abandoned in April 1960. ³
• Coal production stopped in 1961, and the mine was kept open until 1978 for Graig Merthyr's ventilation and pumping. ¹

Photographs & further reading

Sources

1. (secondary) Welsh Coal Mines: Clydach Merthyr Colliery — Welsh Coal Mines
2. (secondary) NMRS coal mining accidents and deaths database — Northern Mine Research Society
3. (primary) BGS / Mining Remediation Authority mine plan: CLYDACH MERTHYR, ABERGELLI (Swansea Four Feet), abandoned 13 April 1960 — British Geological Survey

Record created: 10 October 2026 · Last researched: 10 October 2026