Cilgwyn slate quarry site, Nantlle

Cilgwyn slate quarry site, Nantlle

Here the Snowdonia Slate Trail passes the eastern end of the old Cilgwyn quarry complex. This is where slate quarrying in North Wales may have started. Quarrying was happening here by the 13th century. Slates from this area have been found at the Roman fort in Caernarfon.

There were various small quarries at Cilgwyn before the Victorian era, when they were amalgamated and slate extraction focused on larger quarry pits. The pit nearest to here was called Gloddfa Glytiau, meaning ‘patches quarry’. Immediately west was the Old Cilgwyn Quarry. To its south was the pit known as Faingoch or Veingoch, denoting a red vein of slate.

Waste rock was tipped south and south west of the pits, either side of the incline which carried the saleable slate downhill to the Nantlle Railway near Talysarn. The quarry’s narrow-gauge railway system was extended in the late 19th century to an off-site tip, as you can read on this page.

The quarry used water and even wind power before steam engines were installed. They drove water pumps, via long rods which moved back and forth. They also hauled slate out of the pits and powered slate-processing mills. In 1902 the quarry was the first in the area to use electricity, thanks to its visionary manager Alwynne Carter. A steam engine was connected to an electricity generator to power a pump and rock drills, and later an aerial cableway which lifted slate from the workings.

An earlier Cilgwyn manager, Ellis Williams, allowed the quarrymen to choose their own doctor. Usually managers and owners appointed quarry doctors, who weren’t as independent as they might have seemed at inquests and inquiries. In 1860 Cilgwyn workers thanked Ellis for his fairness by commissioning portraits of him and his wife.

See the footnotes for details of some of the many accidents at the quarry. Large explosions, watched by a crowd, occasionally cleared volcanic rock so that good slate could be quarried. After the Caernarfon Assizes in November 1902, Judge Bucknill travelled to Cilgwyn to light the fuse for a “great blast” which brought down 300 to 400 tonnes of 'granite' and created employment for 150 extra workers.

The quarry closed in 1956 and the site was used as a refuse tip. 

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Footnotes: Some Cilgwyn quarry accidents

In 1858 Owen Prichard of Llandwrog hurried to the spot where he had blasted rock, instead of waiting a while. A loosened rock fell from above, killing him.

In 1890 Owen Hughes of Groeslon was thrown from the quarry wagon in which he was descending. His father had died in almost the same place a year earlier. Owen’s death left his widowed mother with no financial support.

In 1896 slate splitter John Jones of Llanllyfni slipped and fell while moving a slate slab, which fell onto his chest. His spine was fractured and he died the next day.

In 1910 William Evan Jones of Cilgwyn fell c.55 metres (60 yards) to his death after the moveable platform on which he was working was suddenly tipped upwards. The hook of a quarry wagon had caught the edge of the platform.