Great Mountain Colliery

Overview

The Gwendraeth Valley's largest and most productive anthracite mine, a set of long slants at Tumble opened in 1887. Its imported strikebreakers sparked the Tumble riots of 1893, sudden outbursts of coal and gas killed five men in 1935 and 1958, and it closed in 1962, its men moving to Cynheidre.

History

The Great Mountain Colliery Company drove its Nos. 1 and 2 slants, the intake and return drifts, into the Green Vein at Tumble in the Gwendraeth Valley in 1887, and the mine grew into the largest and most productive in the valley, raising 2,000 tons of anthracite a week with 700 men by 1892. Its drifts were among the longest and deepest in the valley, and it worked seven seams, the Big Vein by pillar and stall and the Green Vein by longwall and later the Braslyd, Gras, Stanllyd, Triquart and Pumpquart, ventilated by a 20-foot Waddle fan and served by the Llanelly and Mynydd Mawr Railway. In September 1893, during a bitter strike, the owners brought in strikebreakers from Scotland and England; strikers wrecked their lodgings and the manager's house, which they tried to blow up with gunpowder, and the Inniskilling Dragoons were sent to escort the strikebreakers away. Owned by John Waddell and Sons in 1890 and by the Great Mountain Anthracite Collieries Company in 1896, it employed 842 men by 1913. In 1924 it was bought with the Ammanford Colliery Company for £500,000 by United Anthracite Collieries, which merged into Amalgamated Anthracite Collieries in 1926; the 1924 prospectus credited Great Mountain with more than half of a combined output of 435,000 tons a year. A No.3 Pit, an upcast shaft 18 feet across and 600 yards deep, was sunk in 1939-41. The mine was plagued by sudden outbursts of fine coal and methane, 37 of them between 1913 and 1959: two men died in one on 31 October 1935 and three on 25 February 1958, after which the government told the Commons that inspectors would review the precautions at the colliery. A union survey of 1948-61 found that 40 per cent of its men had pneumoconiosis to some degree, and in January 1948 the collier William King set an anthracite-region record by filling 71 tons in a week from a 30-inch seam by pick and shovel. Nationalised in 1947 with over 900 men, it closed on 5 May 1962 and its men moved to the new Cynheidre colliery; the No.1 slant was kept to pump water for Cynheidre until 1986, and the No.3 Pit became Cynheidre's upcast shaft.

Geology

Anthracite of the western South Wales coalfield: the Big, Green, Braslyd, Gras, Stanllyd, Triquart and Pumpquart seams, prone to outbursts of coal and methane; the Big Vein varied from nine feet to under three feet along a single face.

Geological setting: Sedimentary Beds and Seams (well documented example)

Workings

Slants (drifts) rather than shafts: Nos. 1 and 2, intake and return, driven into the Green Vein in 1887, two more opened in 1906, with man-riding at 6 mph; the No.3 Pit, an upcast shaft 18 feet in diameter and 600 yards deep, sunk 1939-41. Waddle fans (20 ft, and a new 7 ft 6 in fan in 1951), its own washery and a central power station.

Closure

The slants closed on 5 May 1962 (NMRS; Welsh Coal Mines and Coflein give 1962) and the men were transferred to Cynheidre. The No.1 slant stayed open to pump water for Cynheidre until 1986, and the No.3 Pit, deepened in 1955, became Cynheidre's upcast shaft.

What remains

Unknown.

Unknown.

Related mines

• Cynheidre Colliery — Great Mountain's No.3 Pit became Cynheidre's upcast shaft and its No.1 slant pumped water for Cynheidre until 1986; its men transferred there in 1962.

Nearby mines

• Blaenhirwaun Colliery — 1.1 km NE
• Cross Hands Colliery — 3.4 km NE
• Cwmgwili Colliery — 3.8 km SE
• Gwendraeth Colliery — 3.9 km W
• Emlyn Colliery — 5.1 km NE

Straight-line distance, within 15 km. Show on the map.

People

• John Davies · manager, 1900–1908 — Manager of Great Mountain in 1900 and 1908.
• William King · worker, 1948 — Collier, 41, who in January 1948 filled 71 tons in a week by pick and shovel, a record for the anthracite region.

Recorded claims

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

• Work began on the No.1 intake and return drifts in 1887 with the formation of the Great Mountain Colliery Company Ltd; by 1892 the mine produced 2,000 tons a week with 700 men. ^1,2
• In September 1893 the owners imported strikebreaking miners from Scotland and England; strikers attacked their lodgings and the manager's house, which they tried to blow up with gunpowder, and the Inniskilling Dragoons were brought in. ¹
• Owned by John Waddell and Sons in 1890 and the Great Mountain Anthracite Collieries Company in 1896, it was bought in 1924 by United Anthracite Collieries, which merged with Amalgamated Anthracite Collieries in 1926. ¹
• Between 1913 and 1959 the mine suffered 37 outbursts of fine coal and methane; Edgar Owen Collins and Llewellyn Evans died in one on 31 October 1935, and Kenneth Melville Jenkins, William Glyn Jones and Ieuan Lewis in one on 25 February 1958. ^1,2
• Three men were killed at Great Mountain Colliery, Tumble, on the evening of 25 February 1958 by a sudden outburst of coal; HM Inspectors of Mines investigated and reviewed the colliery's precautions. ³
• The Great Mountain Colliery closed in 1962; the No.1 drift stayed open for years afterwards as a pumping station. ^1,2,4

Photographs & further reading

Sources

1. (secondary) Great Mountain Colliery — Northern Mine Research Society
2. (secondary) Great Mountain Colliery — Welsh Coal Mines
3. (primary) Tumble Colliery, Carmarthenshire (Accident), HC Deb 27 February 1958 vol 583 cc547-8 — Hansard
4. (secondary) Great Mountain Colliery, Tumble (NPRN 421100) — Coflein (RCAHMW)
5. (primary) Great Mountain Tip No 33 (Mining Remediation Authority plan, via BGS catalogue item 21835250) — British Geological Survey / Mining Remediation Authority

Record created: 19 September 2026 · Last researched: 19 September 2026