By Rafe Calder
In 1898, Welsh slate production reached half a million tons. Seventeen thousand men worked in the industry.
Those numbers come from the Wikipedia article on the Slate Landscape of Northwest Wales, which says production peaked at over half a million tons in 1898 with 17,000 men employed. The Welsh slate article says much the same. It adds that by the late 1870s Wales produced 450,000 tons a year, against 50,000 for the rest of the United Kingdom combined.
The big three
Wikipedia’s slate article names the major quarries. Penrhyn, near Bethesda, was the largest slate quarry in the world. Dinorwic, near Llanberis, was the second largest. At Blaenau Ffestiniog the slate was mined underground, and the Oakeley mine was the world’s largest slate mine. The Nantlle Valley had its own quarries, and there were smaller workings at Corris, in Pembrokeshire and on Anglesey.
The listing article gives the scale in tons. Penrhyn employed 500 men by 1792 and produced 15,000 tons a year. By the late 1860s Dinorwig was producing 80,000 tons a year and the Nantlle Valley quarries 40,000.
The pit at Penrhyn
Wikipedia’s Penrhyn Quarry article says the first documented slate extraction there dates to 1570, mentioned in a Welsh poem, and that the quarry was developed in the 1770s by Richard Pennant, later Baron Penrhyn. At the end of the nineteenth century it was the world’s largest slate quarry. The main pit measures nearly a mile long and 1,200 feet, or 370 metres, deep. Employment peaked at nearly 3,000 quarrymen at the century’s end, and it now employs about 200, the article says.
The mountain at Dinorwic
Wikipedia’s Dinorwic Quarry article says commercial operations began in 1787 and the quarry closed in July 1969. It lies between the villages of Llanberis and Dinorwig in Gwynedd. At the late nineteenth-century peak it employed more than 3,000 men, and about 2,000 by 1930. It covered 700 acres, in two main sections of 20 galleries each.
The article says the Padarn Railway opened as a horse-drawn, two-foot-gauge tramway in 1824 and was replaced by a steam railway of four-foot gauge in 1848, running until 1961. The listing article gives a conversion date of 1843, another small disagreement between sources. After closure, Gwynedd County Council placed a preservation order on the Gilfach Ddu workshops in December 1969. They were later leased to the National Museum and Galleries of Wales, and the National Slate Museum is now housed there, according to Wikipedia. We have not checked its opening hours or what it shows.
The railways
Slate is heavy, and the quarries are in the hills. The listing article gives dates for the lines built to carry it: Penrhyn Quarry Railway in 1801, Padarn Railway in 1824, Nantlle Railway in 1828, Ffestiniog Railway from 1833 to 1836, Corris Railway in 1859 and Talyllyn Railway in 1866. The Penrhyn Quarry article gives 1798 for its own railway, so sources differ by three years. Both agree it was one of the earliest railway lines.
How the work was organised
The listing article says Welsh-speaking quarrymen formed “bargain gangs” of three to eight workers, and that the North Wales Quarrymen’s Union had 8,368 members by May 1878. We have not found a source that explains how a bargain was struck, so we will not guess.
The strike
Wikipedia gives two disputes at Penrhyn. The first, in 1896, lasted 11 months. The second began on 22 November 1900 and lasted three years, and the article calls it the longest dispute in British industrial history. The Welsh slate article says about 2,800 workers were involved, that about 500 went back when the quarry reopened in June 1901, that others were blacklisted, and that the workers gave in in November 1903.
Splitting
The raw rock is Cambrian, according to the slate article, with some Ordovician and Silurian deposits. The article says that splitting blocks into roofing slates resisted mechanisation and went on needing a mallet and chisel. That is a short sentence that carries a good deal. Our reading is that this part of the work depended on a person judging each block, though no source we read says so in those words.
Roofing was only one use. The same article lists flooring, worktops, headstones and the surfaces of snooker and billiard tables.
Decline
The article says the larger quarries closed in the 1960s and 1970s: Dinorwic in 1969 and Oakeley in 1971. By 1972 fewer than 1,000 men were employed in the North Wales operations. The causes it lists are competition from tile, import tariffs and the world wars. The listing article gives employment as 7,589 men in 1939 and 3,520 at the end of the war, which is a steep fall before the closures began.
Penrhyn survives. Wikipedia says it is still Britain’s largest slate quarry, though it has been overtaken globally by operations in other countries. That puts the 1898 figures in perspective: the quarry that led the world now employs about 200 people, against nearly 3,000 at its peak.
The listing
On 28 July 2021 the slate landscape of north-west Wales was made a UNESCO World Heritage Site. The listing includes six areas: Penrhyn Quarry and the Ogwen Valley to Port Penrhyn, the Dinorwig Quarry mountain landscape, the Nantlle Valley, the Gorseddau and Prince of Wales quarries, Ffestiniog and Porthmadog, and Abergynolwyn and Bryn Eglwys with the Talyllyn Railway.
What to ask a roofer
If a roof here is slate, ask where the slate came from and when it was laid. We did not find a source that says how to tell a Welsh slate from another by eye, so we are not offering a test.
Roam first. Shop later.
Makers working with slate and local stone can find out what’s involved at /sell-with-sephari/