Ynisdavid Colliery

Overview

A colliery at Cwmavon near Port Talbot, one of five worked by the Governor and Company of Copper Miners in England to feed their copper works in the valley. It took the Big, Five Feet, Lower Four Feet, Balance, Upper Four Feet, Finery and Sulphur seams — a seam list that names the industry it served. An explosion of gas on 24 May 1856 killed twelve colliers, eight of them burnt and four suffocated, found lying within a short distance of one another. The colliery was abandoned in 1872.

History

Ynisdavid stood at Cwmavon in the Afan valley, and belonged not to a coal company but to the Governor and Company of Copper Miners in England, the proprietors of the extensive copper and tinplate works at Cwmavon, who worked five collieries in the valley to fuel them. Its seams carry the marks of that trade: alongside the Big, Five Feet, Upper and Lower Four Feet and Balance are the Finery and the Sulphur, named for the ironmaking hearth and for the mineral that made the coal hard to burn cleanly.

On the morning of 24 May 1856 gas exploded in the workings and killed twelve men and boys (see Disasters, below); the Inspector of Mines' annual report for that year carries it as a single line in the table of fatal accidents, under the name of the place rather than the pit. The colliery was abandoned in 1872.

It should not be confused with the other Cwmavon pits on the same ground. The Meadow Pit, also called Waun, opened about 1850 a little to the west, and it was there — not at Ynisdavid — that six men were killed on 24 June 1879 when the rope broke and the cage fell down the shaft.

The colliery's own plans survive only within the Cwmavon district abandonment plans held by the British Geological Survey, which list Ynysdavid among some twenty named pits and levels of the works' coalfield, in the Wernddu Riders, Cwmbyr, Bute and Cockshot seams.

Geology

The colliery worked the coals of the South Wales Coalfield on the eastern side of the Afan valley at Cwmavon. Seven seams are recorded: the Big, the Five Feet, the Lower Four Feet, the Balance, the Upper Four Feet, the Finery and the Sulphur. The explosion of 1856 happened in the Big Vein, which the contemporary accounts describe as known to be dangerous ground.

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

Workings

Little of the layout is recorded. The 1856 explosion happened in the Big Vein at about three in the morning by one account and ten in the morning by another, with something like seventy men underground; the dead were found lying within a short distance of each other, which suggests a single district rather than workings spread across the take. Regulations at the colliery required safety lamps only, and two Struvé patent ventilators, each eighteen feet across, were being erected at the time of the explosion but were not yet finished.

Closure

The colliery was abandoned in 1872.

What remains

Nothing is recorded of what survives on the colliery site. Cwmavon remains as a village in the Afan valley above Port Talbot.

Redevelopment

Unknown.

Disasters & major incidents

• Ynisdavid Colliery Explosion, 1856
  24 May 1856 · Explosion · 12 fatalities
  An explosion of gas in the Big Vein at Ynisdavid Colliery, Cwmavon, on 24 May 1856 killed twelve colliers. Eight were burnt and mutilated and four died of the effects of gas and their injuries; they were found lying within a short distance of one another. The ground was known to be dangerous, safety lamps only were allowed, and two large Struvé ventilators were being erected but were not yet finished.

Recorded claims

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

• Ynisdavid Pit at Cwmavon was owned by the Governor and Company of Copper Miners in England and worked the Big, Five Feet, Lower Four Feet, Balance, Upper Four Feet, Finery and Sulphur seams. ¹
• The Inspector of Mines' annual report for 1856 carries a one-line entry in its table of fatal accidents naming the pit as Cwmavon: an explosion of gas on 24 May which killed twelve men, all colliers. ^1,2
• The colliery was abandoned in 1872. ¹
• The cage disaster of 24 June 1879, in which six men died when the rope broke, happened at the Meadow or Waun Pit at Cwmavon, a separate colliery opened about 1850, and not at Ynisdavid. ¹
• The British Geological Survey's catalogue holds the Cwmavon district abandonment plans (SWR2012), which name Ynysdavid alongside the Balance No.12, Meadow, Engine, Balance No.11, Cwmmawr, Tewgoed Bach, Voel, Tewgoed, Ynysafon, Taskers, Wern, Truro, Victoria, Bryngurnos and Drysiog pits and numbered levels, in the Wernddu Riders, Cwmbyr (Cwmmawr), Bute (Little or Balance) and Cockshot seams. ³

Photographs & further reading

Sources

1. (secondary) Ynisdavid Colliery, Cwmavon — Welsh Coal Mines
2. (secondary) Welsh colliery fatalities, 1856 (Welsh Coal Mines) — Welsh Coal Mines
3. (primary) Mine plans: Cwmavon district / Balance No.12 / Meadow / Engine / Ynysdavid / Balance No.11 / Cwmmawr / Tewgoed ... (abandonment plans SWR2012) (BGS Mine Plans catalogue) — British Geological Survey

Record created: 3 September 2026 · Last researched: 24 September 2026