Pen-yr-Orsedd Quarry

Also known as	Penyrorsedd Quarry, Chwarel Pen-yr-Orsedd
Location	Nantlle, Dyffryn Nantlle, Gwynedd — 53.0602, -4.2241 (approximate)
Commodity	Slate
Type	Slate
Worked	1816–1979
Operators	William Turner (1816–1854), John Lloyd Jones (1854–1862), The Darbishire Company (1862–1979)
Status	Researched

Overview

The last quarry in the Nantlle valley to sell slate commercially, and the place where the Blondin made its final stand: four aerial ropeways installed here in 1906 were still lifting slate out of the pits in 1979, the last working examples anywhere in Britain.

History

Pen-yr-Orsedd opened in 1816 as an open working under William Turner, who also held Dorothea down the valley and Diphwys Casson at Blaenau Ffestiniog. It passed to John Lloyd Jones in 1854 and in 1862 to the Darbishire company, already owners of the Penmaenmawr granite quarries. The Darbishires spent heavily and at first got little back — the quarry was raising only about 500 tons a year by 1871 — but under William Darbishire's direct management output climbed to nearly 8,000 tons by 1882. Mills were built on three successive levels, and the quarry connected to the 3 ft 6 in Nantlle Railway in 1862, eventually reaching all but its highest levels. It outlasted every other quarry in the valley, closing in 1979.

Geology

Pen-yr-Orsedd works the same Cambrian slate belt as its neighbours, and shares their defining problem: the cleavage stands close to vertical, so the slate had to be taken downwards in pits rather than driven into a hillside as chambers. Nantlle's quarries are consequently a series of deep holes rather than the great underground caverns of Blaenau Ffestiniog, and every one of them had to solve the question of how to lift finished slate out of a hole that kept getting deeper.

Geological setting: Slate and Regional Metamorphism (well documented example)

Workings

A series of pits with mills on three levels, worked with mixed 3 ft 6 in and 2 ft gauge trackwork — the wider gauge for the Nantlle Railway connection, the narrower for internal haulage. Pen-yr-Orsedd's answer to the deep-pit problem was the Blondin: four of them were installed in 1906 with Bruce Peebles electrical equipment, each an aerial ropeway spanning the pit on towers, able to pick a load off the floor and set it down anywhere under the span. That removed the need to rebuild haulage every time the pit went deeper. The external Nantlle Railway connection lasted until 1963; the internal 2 ft gauge lines ran until quarrying stopped.

Closure

Commercial slate production ended in 1979, making Pen-yr-Orsedd the last working quarry in the Nantlle valley — and taking Britain's last operational Blondins out of service with it.

What remains

Abandoned and unsecured, and a well-visited site for mine and quarry explorers, with exploration reports posted repeatedly between 2014 and 2023. The pits are deep and partly flooded and the standing structures are decaying.

Exceptional, and internationally significant: the Blondin towers survive, several now toppled, along with the last Blondin still in place on its cable — the only one of its kind left standing in Britain. The mills, pit edges, tramway formations and quarry buildings all remain.

Redevelopment

None. The quarry forms part of Component Part 3, the Nantlle Valley Slate Quarry Landscape, of the Slate Landscape of Northwest Wales World Heritage Site.

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.

The quarry opened in 1816 as an open working under William Turner, who also owned Dorothea and Diphwys Casson. ¹
John Lloyd Jones acquired it in 1854 and sold it to the Darbishire company, owners of the Penmaenmawr granite quarries, in 1862. ¹
Output was about 500 tons a year by 1871, rising to nearly 8,000 tons by 1882 under William Darbishire's direct management. ¹
The quarry connected to the 3 ft 6 in Nantlle Railway in 1862; most levels carried both 3 ft 6 in and 2 ft gauge track, the external connection lasting until 1963. ¹
Four Blondin aerial ropeways with Bruce Peebles electrical equipment were installed in 1906, and were the last working examples in Britain when the quarry closed. ^2,1
Pen-yr-Orsedd closed in 1979, the last quarry in the Nantlle valley to produce slate commercially. ^1,3
The quarry forms part of the Nantlle Valley component of the Slate Landscape of Northwest Wales World Heritage Site, inscribed in 2021. ⁴