If you visit the National Slate Museum in Llanberis, Gwynedd, you can watch slate- makers splitting apparently solid blocks of stone into slates using nothing more than a wooden hammer, a broad chisel, and a lot of skill. Every time you think they cannot possible get a thinner piece, they split the slate again.
These thin sheets of stone make the ideal roofing material: they are easy to transport, can be cut into a variety of shapes, and, being lighter than other forms of stone tile, they do not need such substantial roof timbers or such a steep roof pitch to support them.

Roofing the world
Taking advantage of this fine-grained metamorphic rock, the slate-makers of North Wales can claim to have ‘roofed the world’. Half the buildings in New York were once kept dry using Welsh slate, as was the Governor’s Palace at Williamsburg in Virginia. The decorative properties of differently shaped and coloured Welsh slates were greatly appreciated by the builders of the dome of the Royal Exhibition Building in Melbourne, Australia, built in 1879. It was the roofing material of choice for the huge number of terraced houses built in cities such as Liverpool, Bristol, London, and Dublin during the 19th and early 20th centuries. Those same Victorian and Edwardian houses probably have a damp-proof course of Welsh slate.

A different type of slate – less fissile, but capable of being sawn, milled, and polished to a smooth surface – was used for the hearth stones, fireplaces, and doorsteps of those houses, and for paving the streets beyond. Churchyards in Wales and the west of England are filled with upright slabs of grey-blue slate in the form of tombstones with epitaphs in florid 18th- and 19th-century lettering, still as crisp today as on the day the slate was carved.
Fences of slate are common in the Welsh countryside, while billiard tables of slate are the staple of London clubs and grand National Trust properties. Being non-conductive, slates were used for mounting electrical switchboards until the late 1960s; some slate ended up being used for urinals in public conveniences, or for brewery vats, cisterns, or dairy and larder shelves. Until the early years of the 20th century, children routinely learned to write and add up using slate pencils and ‘ciphering slates’.

Slate: Roman to medieval
The properties of Welsh slate were certainly known to the builders of the 2nd-century AD Roman bath house at Tremadoc, Gwynedd, which was roofed with blue-vein slate from quarries at Nantlle, south of Caernarfon. Similar slates laid in a diamond pattern, fixed by a nail through the apex, were used for the roofs of the Roman barracks at Chester and for the late-Roman villa at Abermagwr, near Aberystwyth, though the slate tiles roofing the mithraeum at Segontium (Caernarfon) were laid longways, like a modern roof.
Spindle whorls of slate are known from both Roman and medieval contexts; so too are fragments of slate palette, probably used for grinding cosmetics or medicine. Roman tombstones of slate have been found at Chester and Segontium, while a post-Roman example was found in 1967 on Ramsey Island, Pembrokeshire: this memorial to Saturnbiu, a 9th-century bishop of St Davids, is now in the National Museum Wales.

Somehow the skills involved in the quarrying and splitting of slate that were clearly present in the Roman period survived into the medieval period. There is documentary evidence for slate being used as a roofing material from the 13th century, and this is confirmed by excavation evidence from the palace of the princes of Gwynedd, near Newborough, on Anglesey.
Edward I’s builders made extensive use of local slate in the castles and bastide towns that they built from 1277 onwards, and beyond the borders of Wales there is evidence for slate being exported to Cheshire and Shropshire, to the south-west via the port of Bristol, and to the east coast of Ireland through the ports of Dublin and Carrickfergus.
A sublime industry
Slate-working remained a small-scale craft employing a few hundred people until the 19th century, when it exploded into a worldwide industry employing tens of thousands. Nobody would have anticipated this growth as the century dawned: shipping insurance costs soared after the outbreak of the Napoleonic Wars, especially for ships negotiating the Channel to get to London.
A tax on slates carried by coastal shipping, imposed in 1784 and not repealed until 1831, further depressed demand for Welsh slate, and gave the advantage to quarries with access to the inland waterways network. The breakthrough came when the Ffestiniog quarries won the contract to supply the slate used in the rebuilding of Hamburg after the Great Fire of 1842, and the trade grew rapidly in the next decade, with the spread of the UK railway network and the abolition of tariffs. The high-water mark for Welsh slate exports came in 1889, a year before several countries reintroduced tariffs to protect their domestic slate industries.

During the period of maximum expansion – roughly 1851 to 1874 – the landscapes of the slate-quarrying areas of Wales were transformed, as were the lives of people of North Wales. To meet the new demand created by urban expansion, quarries were worked round the clock, with men and boys, recruited from the farms of North Wales, trying to master new skills by the guttering light of an oil lamp.

Small-scale concerns had to gear themselves up to mass-production, equipping themselves with mills, water wheels, steam engines, and pumps. Transport had to adapt: horse-drawn carts that had previously carried small slate blocks along turnpike roads were rapidly replaced by narrow-gauge railways capable of carrying hundreds of wooden packing cases filled with slate tiles down to the harbours of North Wales for loading on to ships destined for all four corners of the globe.
The six decades of maximum production have produced a distinctive landscape that is now in line for nomination as a World Heritage Site. Some might have called this an ugly landscape in the past, but we are now used to describing the remains of industry in more Romantic terms. Wordsworth used the word ‘sublime’ to describe his favourite Lake District peaks, and recalled the feelings of awe that he experienced when faced with nature’s most dramatic forms.
Today the term ‘industrial sublime’ can aptly be applied to the Welsh slate landscapes of Snowdonia. Of the 100 or so individual quarries in the four historic counties of North Wales (Caernarfon, Denbigh, Flint, and Merioneth), three of the biggest – Penrhyn, Dinorwic, and Oakeley – are vast open holes in the ground, characterised by huge stepped terraces, like a very steep staircase of stone. Less visible, but even more dramatic, are the underground quarries – like the one that can be visited at Llechwedd – resembling a vast honeycomb of individual chambers, separated by pillars of rock.

Waste tips are an even more dominant element in this landscape, fanning out from the extraction site to form huge hills of fractured slate that, when viewed from the air, form patterns that resemble the petals of a giant flower. These massive piles represent some 90 per cent of the stone extracted from the ground, as not all slate is capable of being worked: an awful lot of stone has to be shifted in order to gain the precious few blocks that can be split easily.
Some of this stone was not dumped, but was used to construct the many different types of building that sprang up to support the industry among the fields of Snowdonia, from blacksmith’s forges and gunpowder stores to the waterwheels and engine houses driving the massive beam engines and pumps that kept the caverns and quarries dry and ventilated.


Workshops were constructed for sawing, splitting, and planing the slate, as were all the associated offices where clerks were employed to administer the industry. Whole new towns were built, complete with barracks for bachelors and cottages for married slate-workers, and the chapels, schools, hospitals, libraries, and institutes that the slate-workers paid for themselves by collecting subscriptions they could ill afford.
Gauging the railways
Railways that are now an important part of the North Wales tourist economy are another highly visible element in this Welsh slate landscape. When railways were being developed in the 1830s and 1840s, different companies experimented with a variety of different gauges. Brunel famously developed a wide-gauge railway that was found to be the most stable and most comfortable for passengers, but that was also, to the chagrin of the Great Western Railway’s shareholders, considerably more expensive to build than the standard gauge that is now used universally for passenger and freight transport.
Passenger comfort was not a consideration in the case of the North Wales slate industry, where narrow-gauge railways, with a two-foot gauge, developed out of their horse-drawn predecessors and proved to be a cheap and effective means of transporting stone through the fields and hills of North Wales: in 1836 a quarry railroad was built to connect the slate village of Blaenau Ffestiniog with the new harbour and growing town of Porthmadog, 21.6km to the west. Today the Festiniog railway is renowned throughout the world as a pioneering example both of narrow-gauge railway construction and, thanks to the passion of many volunteers and enthusiasts, as one of the world’s first preserved steam railways.
As well as using less material and being cheaper to construct, the great advantage of the narrow-gauge railway was its ability to squeeze through tight gaps and run along slender embankments, hugging the sinuous contours of the Snowdon mountains. Another of the Welsh slate industry’s claims to the universal value that underpins World Heritage Site status is that the Festiniog railway engineers pioneered the technology that was subsequently exported to many other parts of the world with rugged and mountainous terrain – most notably the Darjeeling Himalayan Railway, which is already a World Heritage Site.

Splitting power
Also part of this distinctive Welsh slate landscape are the huge estates of the wealthy and powerful quarry owners – ‘strangers’, as these English aristocrats were known in 19th-century Wales: the Assheton Smiths, the Douglas-Pennants (later the Lords Penrhyn), the Oakeley family, and a whole raft of bankers, lawyers, and businessmen who were also part of this complex industry. Now owned by the National Trust, Penrhyn Castle survives as an enormous neo-Romanesque extravagance where the quarry owners lived, overlooking the picturesque estuary of the Cegin river to the east of Bangor.
Guests of Richard Pennant, the entrepreneur who developed the Penhryn quarry, would be driven out on a Sunday after lunch to view and admire the massive stepped face of the quarry, and a painting that hangs in Penrhyn Castle, the work of Henry Hawkins, depicts the leisured visitors, relaxing with sketchbooks in open-necked shirts and carrying walking sticks, while the quarrymen work like ants in the background in a scene that looks like the construction of the Tower of Babel in a Cecil B deMille Biblical epic.

There could be no greater contrast between the leisured lives of the owners and the daily grind of the quarrymen and slate-workers, enslaved to the daily rhythm of work that demanded great strength and skill. For six days a week, the quarrymen followed a set routine, spending the first few hours of every day laying an explosive charge by driving a long iron stake into fault lines in the slate, in order to open up a channel into which gunpowder could be laid. At a given signal, the men would retire to their caban, there to eat and talk and discuss politics and religion while the blasting took place. Unworkable rock and waste would then be cleared and taken away to add to the giant tips, while workable slate was loaded by crane on to wagons to be taken to the workshops and mills.
Hard as it was, life in the Welsh slate industry was not without benefits compared, for example, to factory work or agricultural labour. Instead of a fixed wage, many men were employed on a ‘bargain’ system, whereby they were allocated an area within the quarry and contracted to supply a certain quantity of worked slates. How they did this was up to them; in effect, the industry was run on the basis of many small partnerships of five to a dozen men, each responsible for different activities, from extraction to the delivery of the finished slates.
This was a system that partly depended on luck – for the quality of the rock varied from place to place, and you could end up working poor-quality slate, or you might lose days through sickness, injury or bad weather – but it also rewarded hard work and allowed for profit-sharing. Skilled men commanded a premium, so there was an incentive to get on, hoping to climb the skill ladder from rubbleman to slate splitter.

Craft skill was at the heart of the industry, but other careers, less physically demanding, were available to those who mastered the knowledge to become clerks and inspectors, accountants or engineers. School learning was thus greatly valued, as was the ability to communicate in Welsh with the labour force and in English with the managers, shareholders, owners, and customers.
Not to be slated
It was possible, then, to become relatively prosperous in this industry through hard work and application; consequently, entry to the industry was jealously guarded, with some jobs being passed from father to son, or being under the control of one chapel congregation or another. The legacy is a vital culture – an intangible heritage in UNESCO terms – that is alive and well among the slate communities of North Wales, a blend of political radicalism, a strong work ethic, and a commitment to temperance and teetotalism, to education, and to Protestant non-conformity.
It is easy to mythologise the cultured slate quarryman, but the tangible evidence exists in their heritage of chapels and institutes where the community would gather for sermons, lectures and meetings of the Workers’ Educational Association, choir practice, and singing competitions and poetry readings; it is also evident in the University at Bangor, established in 1884 with the contributions of the slate quarrymen.

The caban was central to this culture, functioning as a debating club, under the watchful eye of a chairman or chapel deacon, as well as a works canteen. Welsh-language newspapers were read avidly in the caban, and the news discussed and digested along with lunch. Politics, religion, literature, and music were central to caban culture; there was also much banter, and the caban had as many pin-ups on the walls as notices of forthcoming lectures or union meetings. Even so, the industry fostered a working-class culture that is sophisticated, well-informed, community-minded and outward-looking.
Above all, this was a strongly Welsh-speaking culture, and the language was kept alive and robust as a consequence at a time when it could so easily have been lost to the growing dominance of English in education and the media. The role of the industry in keeping Welsh alive is as important a part of the claim to ‘universal value’ that is central to World Heritage Site status as the claim to have ‘roofed the world’ or to have exported slate-quarrying skills and narrow-gauge railway technology to the rest of the world.
A Welsh World Heritage Site?
In writing about the Welsh slate industry, it is difficult to adopt a consistent tense: this is both a historic industry, core to the Industrial Revolution, and a living industry, still producing slate that competes in world markets alongside producers in Spain, Brazil, China, and India. That makes it all the more surprising that a number of different organisations have come together to support the nomination of the Welsh slate landscape as a potential World Heritage Site.
UNESCO, the guardian of World Heritage Site status, has for a decade or more favoured cultural landscapes over individual sites, seeking to inscribe areas in which many different but interconnected forms of heritage are preserved, including the deep-mining landscapes of Cornwall and the iron and coal landscapes of Blaenavon, complete with its workers’ cottages, church, school, Workmen’s Hall, its furnaces, casting houses, and calcining kilns, its railway and canal systems. On that basis, the Welsh slate industry scores highly, for it is possible still to read the entire history of the industry in the legacy of quarries, mills, railways, and communities.

But UNESCO has always found it difficult to embrace change in the landscapes that it designates, as has been made clear by recent UNESCO investigations into the impact of new buildings on Bath, Edinburgh, and Westminster. Dresden’s Elbe Valley was awarded the title of World Heritage Site in 2004 for its 18th- and 19th-century landscape that extends 18km (11 miles) along the Elbe, and includes central Dresden and several baroque palaces and gardens. It then suffered the ignominy becoming only the second site in World Heritage Site history to have that status removed, in 2009, when UNESCO officials took the view that the construction of a four-lane motorway bridge over the river had irreversibly damaged the designated landscape. Concern is even now being expressed about the impact on the Cornish mining landscape of the reopening of some of the mines to extract minerals that are now gaining in value on world markets.
How, then, is UNESCO going to respond to the nomination of a landscape that is not relict, and that continues to produce slate, albeit now with mechanical diggers, fork-lift trucks, and diamond-tipped saws rather than hammers, chisels, and human skill? Slate production underpins the livelihoods of many people in Gwynedd, and the history of the Welsh slate industry is a matter of huge pride to all connected with it.
It is possible that, by posing a challenge to UNESCO to think about how to resolve potential conflicts between heritage and livelihoods, the Welsh slate industry will be able to claim yet another achievement: changing the outlook and practices of conservation specialists the world over.
Further reading
David Gwyn, Welsh Slate: archaeology and history of an industry, RCAHMW, £45, ISBN 978-1871184518.
All images: Crown Copyright: Royal Commission on the Ancient and Historical Monuments of Wales.