Cwm Colliery, Merthyr Tydfil

Overview

A shallow Cyfarthfa Works pit at Rhyd-y-car, Merthyr Tydfil, sunk in 1845 under Robert Thompson Crawshay. It employed over 1,000 people by 1908, stopped work in 1910 and was kept for drainage until 1924.

History

Cwm Colliery, also called Cwm Pit, was sunk in 1845 under the management of Robert Thompson Crawshay as part of the Cyfarthfa Works. It lay at Rhyd-y-car, at the head of the 1766 tub-boat canal that served the Cyfarthfa Ironworks. A shallow pit, it worked the steam coal seams that run close to the surface along the northern edge of the coalfield.

A fall of roof in January 1886 killed three men (see Disasters, below). In 1891 the pit worked the Six Feet, Nine Feet, Bute, Five Feet Six, Upper Four Feet and Upper and Lower Two Feet Nine seams. In 1896 it employed 681 men underground and 99 at the surface, raising steam coal. A firedamp explosion on 14 May 1900 caused serious injuries but no deaths. The Home Office report on it judged most of the fuses then used in mining distinctly dangerous.

By 1908 Crawshay Brothers (Cyfarthfa) Ltd owned the pit, which employed 897 underground and 143 at the surface under the manager Mat Truran. It closed in December 1910 but was kept as a watercourse for drainage until it was abandoned in 1924.

Geology

South Wales Coal Measures at the northern outcrop of the coalfield: the Six Feet, Nine Feet, Bute, Five Feet Six, Upper Four Feet and Upper and Lower Two Feet Nine seams, worked for steam coal.

Workings

A shallow shaft with a chimney, screens and an incline crossed by a bridge; after 1910 the pit served as a watercourse draining the workings.

Closure

Coal working stopped in December 1910. The pit was then kept as a watercourse for drainage until it was abandoned in 1924. The reason for closure is unknown.

What remains

Much stonework and many foundations survive, including the base of the chimney, a capped shaft, the abutments of the incline bridge and the area below the screens.

Chimney base, shaft cap, incline-bridge abutments with a recess beneath, and the screens area with a short tunnel and iron control rods.

Redevelopment

Unknown.

Related mines

• Cwmdu Colliery, Merthyr Tydfil — Cyfarthfa pit planned with Cwm Pit in the same joint abandonment plans.
• Cyfarthfa Ironworks — Sunk in 1845 as one of the Cyfarthfa Works' own coal pits.

Disasters & major incidents

• Cwm Colliery roof fall, Merthyr, 1886
  28 January 1886 · Collapse / Roof Fall · 3 fatalities
  On the morning of Thursday 28 January 1886 two falls of roof in a stall of the Seven Foot vein at Crawshay Brothers' Cwm Pit, Merthyr Tydfil, killed three men, including the fireman sent to clear the first fall, and injured a fourth. The inquest returned accidental death.

Recorded claims

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

• Sunk in 1845 under the management of Robert Thompson Crawshay as part of the Cyfarthfa Works. ^1,2
• Employed 681 men underground and 99 at the surface in 1896. ¹
• Employed 897 underground and 143 at the surface in 1908, under Crawshay Brothers (Cyfarthfa) Ltd. ¹
• Closed in 1910 and kept for drainage until abandoned in 1924. ^1,2
• Stonework and foundations survive, including the chimney base, a capped shaft and the incline bridge. ²
• Its workings are planned with the other Cyfarthfa pits, including Rhydycar, Colliers Row, Roblins and Cwmdu, in the Gellideg and other seams. ³

Photographs & further reading

Sources

1. (secondary) Waun Wyllt Colliery — Welsh Coal Mines
2. (secondary) Pontypridd to Abercanaid, the Industrial Archaeology and History — Industrial Gwent
3. (primary) Mine plan: Cyfarthfa, Cwm, Upcast, Glyndyrys, Pumping, Rhydycar and other pits, Gellideg — British Geological Survey

Record created: 1 October 2026 · Last researched: 2 October 2026