Easdale Slate Quarries

Overview

Easdale, one of Argyll's Slate Islands off Seil, was quarried for roofing slate on an industrial scale from 1745, at its peak producing around 10 million slates a year — enough that the islands were said to have "roofed the world". The industry ended abruptly on Easdale itself when a violent storm breached a sea wall in November 1881 and flooded the quarries, which had been worked to 250 feet below tide level; 240 men and boys lost their jobs overnight, though no one was hurt.

History

A cargo of Easdale slate is recorded as early as 1168, but organised quarrying dates from 1745, when the Earl of Breadalbane's Marble and Slate Company of Netherlorn took over the workings. Output grew rapidly: around one million slates a year in the mid-18th century, five million by 1800 — helped by pumping machinery that made it possible to work seams below sea level even at high tide — and a peak of roughly ten million slates a year by the late 19th century, from quarries on Easdale and the neighbouring islands of Ellenabeich, Seil and Luing. An 1799 tax on slate carried by sea cut into profits well before the quarries' more dramatic end.

Geology

The quarries worked Dalradian slate of the kind found across Argyll's Slate Islands, extracted from pits sunk close to and below current sea level, protected from the sea by rock and man-made sea walls.

Workings

Workings were sunk as open pits rather than driven underground, reaching 250 feet below tide level on Easdale by 1881; continuous pumping was needed to keep the sea out of pits that extended below the surrounding water level.

Closure

In the early hours of 22 November 1881, a severe south-westerly gale coincided with an exceptionally high tide; a rocky buttress supporting one of the sea walls gave way under the pressure, and by daybreak the quarry — worked to 250 feet below tide level — was flooded beyond what even its large suction pump could clear. No one was killed or injured, as the island's inhabitants had already moved to higher ground, but 240 men and boys were thrown out of work, and the flooded workings on Easdale itself were abandoned for good; the last slate was cut there in 1911, though quarrying continued on the neighbouring Slate Islands into the 1950s. The island's population, over 500 at the industry's peak, had fallen to just four residents by the 1960s.

What remains

The flooded quarry pits, some over 80 metres deep, now form a series of still pools across the island that support wildlife; the Easdale Island Folk Museum preserves artefacts, documents and photographs from the slate industry.

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.

• Output grew from around one million slates a year in the mid-18th century to five million by 1800 and a peak of roughly ten million a year by the late 19th century. ^1,2
• A severe gale and exceptionally high tide breached a sea wall on 22 November 1881, flooding the Easdale quarry (worked to 250 ft below tide level); 240 men and boys lost their jobs, but no one was killed or injured. ^2,3
• Easdale's population, over 500 at the slate industry's peak, had fallen to just four residents by the 1960s. ²

Images

Sources

1. (secondary) Slate Industry — Easdale Island Folk Museum
2. (secondary) Easdale Island Historical Background — Eilean Eisdeal (Easdale community history)
3. (secondary) Easdale, slate quarries and associated workings — ancientmonuments.uk

Record created: 20 August 2026 · Last researched: 20 August 2026