# Dinorwic Quarry

> A vast former slate quarry above Llanberis, Gwynedd, which employed over 3,000 men in the late 19th century and closed in 1969.

- URL: https://roof.wiki/dinorwic-quarry/
- Topic: History of Roofing
- Also known as: Dinorwig Quarry; Dinorwig slate quarry
- Regions: Europe
- First published: 2026-11-02 · Last reviewed: 2026-11-02
- Cite as: "Dinorwic Quarry." roof.wiki. https://roof.wiki/dinorwic-quarry/

## Key facts

- **Location:** Llanberis, Gwynedd, Wales
- **Commercial working began:** 1787
- **Area:** About 283 ha (700 acres)
- **Closed:** July 1969

**Dinorwic Quarry** (Welsh spelling Dinorwig) lies on the mountainside between the villages of Llanberis and Dinorwig in Gwynedd, north-west Wales. Together with Penrhyn it was one of the two giants of the Welsh slate industry.

## History

Commercial working began in 1787 under a private partnership. In 1809 the landowner, Thomas Assheton Smith, took direct control. Slate was carried to the coast by tramway from 1824, and from 1848 by the 4 ft (1,219 mm) gauge **Padarn Railway**, which served the quarry until 1961. Output reached about 80,000 tons a year by the late 1860s.

## Scale

The quarry covers about 283 ha (700 acres), with two main sections each cut into about 20 galleries, or stepped working levels. In the late 19th century it employed more than 3,000 men and produced around 100,000 tonnes of slate a year.

## Closure

The quarry closed in July 1969, with the loss of about 300 jobs. Its workshops at **Gilfach Ddu** were bought by the county council and now house the **National Slate Museum**, which displays the machinery and the traditional skills of splitting and dressing slate.

## Later use

Part of the quarry was used for the **Dinorwig power station**, a pumped-storage hydroelectric scheme built inside the mountain.

## Heritage

In its heyday Dinorwic, with Penrhyn, was among the largest producers in a region that supplied about a third of the world's roofing slate. The Dinorwig area forms part of the Slate Landscape of Northwest Wales, inscribed on the UNESCO World Heritage List in 2021, which recognises how this landscape supplied roofing slate to much of the industrial world.

## Sources

1. Dinorwic Quarry — Wikipedia. https://en.wikipedia.org/wiki/Dinorwic_Quarry
2. Slate industry in Wales — Wikipedia. https://en.wikipedia.org/wiki/Slate_industry_in_Wales