Maenofferen Quarry

Overview

A major Blaenau Ffestiniog slate quarry first worked shortly after 1800 as the open-cast 'David Jones's pit', incorporated as the Maenofferen Slate Quarry Company in 1861. It grew into one of the district's leading producers, transitioning from open working to extensive underground chamber-and-pillar workings, and became notable for an unusually late closure among Blaenau Ffestiniog quarries. Its own No. 2 incline is said to have been the last self-acting incline used anywhere in the Welsh slate industry.

History

Slate was first worked at the site shortly after 1800 by men from the neighbouring Diffwys quarry, in an open-cast working known as 'David Jones's pit', the highest and most easterly part of what became the Maenofferen complex. Slate shipments moved via the Ffestiniog Railway from 1848, with the traffic interrupted in 1850-57 and again briefly in 1865. In 1861 the Maenofferen Slate Quarry Company was incorporated, led by Sir William Fothergill Cooke and Mr Veasey, after leasing the ground from its owner, Lord Newborough. Output grew from around 400 tons in 1861 to 8,600 tons in 1882, by then the fifth-largest producer in the Ffestiniog area, and by 1897 the quarry employed 429 people, nearly half of them underground. A hydroelectric station was installed on site in 1918. In 1928 Maenofferen purchased the neighbouring Rhiwbach quarry together with its tramway, operating it until Rhiwbach's own closure (recorded variously as 1953 or 1962 by different sources). Wire-saw technology for underground slate extraction was pioneered here in the 1970s-80s. Post-war decline, as synthetic roofing materials undercut demand for slate, reduced the workforce to just 60 by 1972, producing 1,200 tons a year. In 1975 Maenofferen, together with the Bowydd workings (incorporating the older Votty ground), was reunited under the ownership of the neighbouring Llechwedd quarry, another J. W. Greaves company. Underground production finally ended in November 1999 (November 1998 by one source), an unusually late closure among Blaenau Ffestiniog quarries; limited surface and tip processing continued under Llechwedd ownership for a few years afterward. A detailed archaeological survey of the workings by the Royal Commission on the Ancient and Historical Monuments of Wales in 2010-11 described the underground complex as an 'exceptionally well-preserved relict' industrial landscape.

Workings

Working began as an open-cast pit but the 19th-century company progressively moved underground and further downhill toward the town, and by the 20th century the quarry was worked entirely underground by chamber-and-pillar methods. The Royal Commission's survey records the underground workings as occupying an area of roughly 1,922 by 480 metres to a depth of 225 metres, with the main processing floor sited over 400 metres above sea level. The quarry was initially linked to the Ffestiniog Railway via the Duffws incline, then, after 1863, via the lower two inclines of the neighbouring Rhiwbach Tramway; a new incline was built in 1920 to bypass that dependency and connect via Votty and Bowydd's own access to the railway at Duffws instead. Maenofferen's own No. 2 incline is said to have remained in self-acting operation until after 1975, by which point it was the last self-acting incline still used anywhere in the Welsh slate industry. After the Ffestiniog Railway's original route closed in 1946, Maenofferen leased track between Duffws station and the standard-gauge yard at Blaenau Ffestiniog to keep its own slate trains running into the early 1960s, making it the last slate quarry to use any part of the railway's original alignment before switching entirely to road transport.

What remains

Above-ground buildings are no longer in industrial use, with abandoned slate-cutting mills visible on site; Llechwedd continues limited crushed-slate and tip processing on the wider site. The underground workings remain extensive and largely intact, with surviving machinery and artefacts recorded across multiple levels by permitted underground visits.

Abandoned workings can be dangerous — unstable ground, uncapped shafts, flooding and bad air are common even where a site looks safe from the surface. This entry describes history and general location only; it is not an access guide.

The quarry's underground workings are extensive and only accessible with permission; a 2013 post-closure incident in which a teenager fell and was airlifted to hospital with non-life-threatening injuries is a reminder that the site remains genuinely hazardous.

Recorded claims

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

• The Maenofferen Slate Quarry Company was incorporated in 1861, led by Sir William Fothergill Cooke and Mr Veasey, after leasing the ground from its owner, Lord Newborough. ^1,2
• Output grew from around 400 tons in 1861 to 8,600 tons in 1882, then the fifth-largest producer in the Ffestiniog area; by 1897 the quarry employed 429 people, nearly half underground. ^3,2
• Maenofferen's own No. 2 incline remained in self-acting operation until after 1975, by which point it is said to have been the last self-acting incline used anywhere in the Welsh slate industry. ⁴
• After the Ffestiniog Railway's original route closed in 1946, Maenofferen leased track between Duffws station and the standard-gauge yard to keep its own slate trains running into the early 1960s, making it the last slate quarry to use any part of the railway's original alignment. ^1,3
• Underground production ended in November 1999 according to Wikipedia, Coflein and TheTimeChamber, but November 1998 according to Festipedia; the discrepancy is not resolved by any source consulted. (disputed) ^1,4
• A Royal Commission on the Ancient and Historical Monuments of Wales survey in 2010-11 described the underground workings as an 'exceptionally well-preserved relict' industrial landscape. ²
• A 2021 observational report describes the underground workings as extensive and multi-level, with surviving machinery and passageways connecting large chambers, reaching Level 7 on a seven-hour permitted visit. ⁵
• The BGS mine plans catalogue holds ten records for Maenofferen, held by Gwynedd Archives Service, including draft plans and sections of the Maenofferen Slate Company's property and a 1963-64 correlation of workings with the neighbouring Votty and Bowydd quarry. ⁶

Images

Sources

1. (secondary) Maenofferen quarry — Wikipedia
2. (primary) Maenofferen Slate Mine, Blaenau Ffestiniog (NPRN 400427) — Royal Commission on the Ancient and Historical Monuments of Wales (Coflein)
3. (secondary) Maenofferen Slate Quarry, North Wales — TheTimeChamber
4. (secondary) Maenofferen Quarry — Festipedia (Ffestiniog Railway history wiki)
5. (observational) Maenofferen Slate Mine (Underground) - August 2021 — Derelict Places forum
6. (primary) Maenofferen mine plan records — British Geological Survey mine plans catalogue

Record created: 26 August 2026 · Last researched: 26 August 2026