Cloddfa'r Lôn Quarry

Overview

The first major slate quarry on the floor of the Nantlle valley, opened in 1808 by William Turner and worked until 1892. It was the first quarry on the Nantlle Railway and brought the Cornish chain incline to Wales in 1841; its scheduled mill, chain incline and quarrymen's cottages survive.

History

Cloddfa'r Lôn was the first major slate quarry to be opened on the floor of the Nantlle valley, worked from 1808 by William Turner. It was the first quarry to be linked to the Nantlle Railway when that line opened in 1828, and a pioneer of steam up-haulage: in 1841 it introduced the Cornish chain incline to Wales, a system in which waggons were raised from the quarry pit on an inclined chain rather than a rope. Between 1836 and 1844 Cloddfa'r Lôn and the neighbouring Penybryn quarry used more traditional water-wheel technology connected by rods to a series of pumps, and the chain inclines seen at both quarries were invented locally. By 1864 Cloddfa'r Lôn employed two hundred men, against the four hundred each at Dorothea and Pen-yr-Orsedd.

Substantial investment in the early 1880s developed this part of the quarry complex on an area of unworkable rock around an existing barracks and Pen y Bryn farm, and it was in those latter years that the quarry worked close to the old farmstead whose name the adjoining quarry carries. The mill built in 1884 was of radial type, holding six De Winton saw tables and driven by a vertical single-cylinder steam engine by W. C. Mather — the only slate mill steam engine to survive in Wales, now at the Welsh Slate Museum in Llanberis. The quarry fell out of use in 1892. Its remains are a scheduled monument, and the Welsh Government's Wales Slate listing names the Pen y Bryn and Cloddfa'r Lôn dwellings, slate mill and chain incline ropeway bastions, and their water-driven pump system, among the notable elements of the Nantlle Valley component of the Slate Landscape of Northwest Wales World Heritage Site.

Geology

The quarry worked the slate of the Nantlle valley floor, the Cambrian slate belt of Caernarfonshire whose veins run north east to south west through the valley. The early 1880s development was pushed onto an area of unworkable rock around the existing barracks and Pen y Bryn farm, which is why that phase produced buildings rather than output.

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

Workings

A pit quarry on the valley floor with two chain inclines. The 1884 radial mill's engine seems also to have driven a chain incline to the north, by which waggons were raised from the quarry pit on an inclined chain; a second chain incline south of the complex is evidenced by a surviving engine house and a strongpoint with a landing platform for the raised waggons, the engine house having held a horizontal steam winding engine and a winding drum. A tramway crossed the turnpike road on a bridge to reach the Nantlle Railway, and a weighbridge house stood to the south. Between 1836 and 1844 the quarry shared with Penybryn a water-wheel pumping system worked by rods.

Closure

The quarry fell out of use in 1892, sixteen years after the substantial investment of the early 1880s that built the mill and the barracks, and having been worked for eighty-four years.

What remains

A compact complex of significant standing remains, scheduled since 24 June 1998. The walls of the mill are complete to eaves height and the substantial boilerhouse chimney is intact; the engine house and strongpoint of the southern chain incline survive, as do the bridge abutments, the weighbridge house and the two rows of cottages, complete to eaves height with their garden plots and outbuildings.

The 1884 radial mill, its walls complete to eaves height, with an intact boilerhouse chimney; the engine house and landing strongpoint of the southern chain incline; the substantial abutments of the bridge that carried the tramway over the turnpike road to the Nantlle Railway, with a weighbridge house to the south; and two rows of barracks amounting to six cottages, thought to have been built about 1866, complete to eaves height with garden plots and outbuildings. The mill's steam engine is no longer on site: it is at the Welsh Slate Museum in Llanberis.

Redevelopment

None. The site is a scheduled monument within the Slate Landscape of Northwest Wales World Heritage Site.

Related mines

• Dorothea Quarry — Neighbouring Nantlle valley pit quarries; in 1864 Dorothea employed four hundred men to Cloddfa'r Lôn's two hundred.
• Pen-y-Bryn Quarry — Adjoining Nantlle quarries, so entangled that the World Heritage Site listing treats their dwellings, mill, chain inclines and pump system as 'Pen y Bryn / Cloddfa'r Lôn'. Between 1836 and 1844 the two shared a water-wheel pumping system worked by rods and connected by locally invented chain inclines, and Cloddfa'r Lôn's last development ran up to Pen y Bryn farm itself. They remain separate scheduled monuments about five hundred metres apart, and Pen-y-Bryn worked on until 1950.

Recorded claims

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

• Cloddfa'r Lôn was the first major slate quarry on the floor of the Nantlle valley, worked from 1808 by William Turner, and fell out of use in 1892. ¹
• It was the first quarry to be linked to the Nantlle Railway on that line's opening in 1828. ¹
• The quarry was a pioneer of steam up-haulage, introducing the Cornish chain incline to Wales in 1841. ¹
• Between 1836 and 1844 Penybryn and Cloddfa'r Lôn used more traditional water-wheel technology connected by rods to a series of pumps, and the chain inclines seen at the two quarries were invented locally. ²
• Substantial investment in the early 1880s developed this part of the complex on an area of unworkable rock around an existing barracks and Pen y Bryn farm. ¹
• The mill was of radial type, built in 1884 to contain six De Winton saw tables and powered by a vertical single-cylinder steam engine by W. C. Mather, which is now at the Welsh Slate Museum in Llanberis and is the only slate mill steam engine to survive in Wales. ¹
• The mill engine seems also to have driven a chain incline to the north, raising waggons from the quarry pit on an inclined chain; a second chain incline south of the complex is evidenced by a surviving engine house, which held a horizontal steam winding engine and a winding drum, and a strongpoint with a landing platform. ¹
• The substantial abutments of a bridge carrying a tramway over the turnpike road to the Nantlle Railway survive, with a weighbridge house to the south, and the two rows of barracks consist of six cottages thought to have been built about 1866, complete to eaves height with their garden plots and outbuildings. ¹
• In 1864 Dorothea and Pen-yr-Orsedd quarries each employed four hundred men, while Cloddfa'r Lôn employed two hundred. ²
• The quarry was scheduled on 24 June 1998 as Cadw monument CN302, classed as industrial and categorised as a slate mill, and is described as a compact complex of significant remains from a leading Nantlle pit quarry, of national importance. ¹
• The Wales Slate listing for the Nantlle Valley names the Pen y Bryn / Cloddfa'r Lôn Slate Quarry dwellings, slate mill and chain incline ropeway bastions, and the Pen y Bryn / Cloddfa'r Lôn water-driven pump system, among the notable elements of the World Heritage Site component. ³

Photographs & further reading

Sources

1. (primary) Cloddfa'r Lon Slate Quarry, Llanllyfni (Cadw scheduled monument CN302) — Cadw scheduling text, via Ancient Monuments UK
2. (secondary) Slate industry in the Nantlle Valley — Wikipedia
3. (primary) Dyffryn Nantlle — Slate Landscape of Northwest Wales — Llechi Cymru / Wales Slate (Welsh Government)

Record created: 28 September 2026 · Last researched: 28 September 2026