Llwydgoed Quarry

Overview

A slate quarry in the Nantlle Valley, one of at least 37 quarries that once worked this west-Wales slate district by digging down through the valley floor rather than quarrying open hillside galleries.

History

Llwydgoed Quarry was one of at least 37 slate quarries at work in the Nantlle Valley during the 19th and 20th centuries, part of a long belt of Cambrian slate, some 500 million years old, running from the Nant Ffrancon valley in the east to Nantlle in the west. Unlike the large integrated enterprises at Bethesda, Llanberis and Blaenau Ffestiniog, the Nantlle Valley's quarries were characteristically run independently and on a much smaller scale. Where the larger eastern quarries could win their slate through open hillside galleries, Nantlle's own slate beds lay beneath the floor of the valley itself, so quarrymen here had no choice but to dig straight down, creating the large pits characteristic of the district. Nantlle slate was consequently always at something of a competitive disadvantage against the more easily won rock at Penrhyn and Dinorwic further east, and was typically the first to suffer whenever the wider slate trade turned down.

Workings

Worked by digging a pit down through the valley floor to reach the slate beds beneath, rather than by open hillside galleries.

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.

Recorded claims

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

• Nantlle's own slate beds lay beneath the floor of the valley itself, so quarrymen here dug pits down to reach them, rather than working open hillside galleries as at Penrhyn and Dinorwic further east. ¹
• Nantlle slate was always at a disadvantage compared to the more easily won rock at Penrhyn and Dinorwic, and was typically the first to suffer from any downturn or recession in the wider slate trade. ¹
• The Nantlle Valley had at least 37 operating slate quarries at one time, of which Llwydgoed was one, run independently and on a much smaller scale than the large integrated enterprises at Bethesda, Llanberis and Blaenau Ffestiniog. ²

Photographs & further reading

This page doesn't try to reproduce everything — these are the best original sources found for this mine.

Sources

1. (secondary) Slate industry in the Nantlle Valley — Wikipedia
2. (primary) Dyffryn Nantlle — Slate Landscape of Northwest Wales — Llechi Cymru / Wales Slate (Welsh Government)

Record created: 30 August 2026 · Last researched: 31 August 2026