Opposite Prior Park, home of philanthropist Ralph Allen, who transformed Bath’s small-scale stone mining industry into a major commercial venture. In the foreground can be seen the wooden railway Allen built to transport the stone. above An artist’s impression of working in the part of the quarry known as the ‘Grand Canyon’.

Hollowed Ground: the archaeology of Bath’s stone mines

The hills around Bath look solid enough but below the surface they are riddled with tunnels and stone quarries. When some of these began to collapse, putting the village of Combe Down at risk, Oxford Archaeology was called in to record this vast labyrinth before it was filled with concrete. Chris Catling reports on the record they made of an industry that helped create the beautiful buildings of Georgian Bath’s ‘Golden Age’.

Start

Nestling in the steep-sided valley of the Avon, Bath Spa has a remarkable degree of homogeneity. This comes in part from having been planned and built over a short period by just two architects, John Wood the Elder and John Wood, his son. But viewed from the Bath Skyline Walk that encircles the city for some six miles, offering the perfect vantage point, it is something else that you notice about the spiky church steeples and long rows of houses that climb up the terraced hillsides from the river. Bath has that quality that William Morris so admired in his own home of Kelmscott Manor or such Cotswold villages and towns as Bibury and Burford: it is built of materials that complement their setting so well that they look as if they are rooted in the soil and have grown like something organic rather than man-made.

Opposite Prior Park, home of philanthropist Ralph Allen, who transformed Bath’s small-scale stone mining industry into a major commercial venture. In the foreground can be seen the wooden railway Allen built to transport the stone. above An artist’s impression of working in the part of the quarry known as the ‘Grand Canyon’.
Prior Park, home of philanthropist Ralph Allen, who transformed Bath’s small-scale stone mining industry into a major commercial venture. In the foreground can be seen the wooden railway Allen built to transport the stone. Image: Building of Bath Collection, www.bath-preservation-trust.org.uk.

Bath is, of course, a bit of both: a human artefact, but made from stone so local that the buildings of Bath form a geological continuity with the limestone bedrock on which they sit. And whereas the architects of such fine stone buildings as St Paul’s Cathedral, in the City of London, or King’s College Chapel in Cambridge, had to ship their stone from distant quarries at vast expense, John Wood, creator of Bath, had an abundance of England’s finest stone on his doorstep.

Precious stone

Bath stone is the queen of building materials, surpassed only by Portland stone, with which it has many similarities. Comprised of myriad rounded granules of calcium carbonate, the remains of broken and eroded marine shell laid down millions of years ago under warm tropical sea, it is called oolitic – egg-like – because of its resemblance to fish roe. When freshly quarried, it is soft enough to be sawn and carved into the crisp acanthus leaves and scrolls that the classical orders demand. It becomes hard as it dries to a creamy yellow colour with hints of warm pink. And it is what quarrymen call a ‘freestone’, meaning that it can be cut and carved in any direction – unlike limestone from higher up in the Great Oolite sequence, which forms distinct layers, into which it can be split by a skilled mason to form rubble stone or to create the roofing tiles that are so characteristic of Bath and the limestone belt that runs north-eastwards from Bath to Stamford and on to Lincoln.

An artist’s impression of working in the part of the quarry known as the ‘Grand Canyon’.

The hills around Bath and on up through the limestone belt are riddled and pitted with ancient quarries, dating back to the Roman period, but these were mostly small and domestic in scale – opened up to supply just enough stone to build a nearby house, or to provide stone for paving a road. Caving clubs and industrial archaeologists have been exploring and mapping these for many years: most are known only to local residents, and many of them now have locked gates to prevent accidents, but also to protect the bat colonies that use them for winter hibernation. Some of the vast quarries in the area around Box and Corsham, in Wiltshire, were used as underground factories and munitions stores during the Second World War, hidden from the sight of aerial bombers. A number of them continued in use as nuclear bunkers during the subsequent Cold War, and several are still security classified sites, while others are operated commercially for storing wine, documents, vintage vehicles, and works of art, all of which benefit from the consistent humidity and temperature that prevails several metres below the ground.

below A section through one of Allen’s quarries, showing the 18th-century mining process.
A section through one of Allen’s quarries, showing the 18th-century mining process. Image: Oxford Archaeology/Lynn Willies.

But these all belong to a different story, and the story Oxford Archaeology (OA) uncovered when called in to record the oldest of the really large-scale underground stone workings in the Bath area is every bit as fascinating. This underlies the village of Combe Down, located a mile south of the centre of Bath, and thus within the designated World Heritage Site area. Extending for some 18 hectares, these had been all but abandoned in 1838, and had now become dangerously unstable, threatening hundreds of houses in Combe Down’s central conservation area above. A stabilisation programme was thus devised that involved constructing 14km of steel and timber roadway to provide safe access into every corner of the mines, which were then filled with some 550,000 cubic metres of foamed concrete. Apart from a few areas designated as a bat sanctuary, this hugely important quarry – an essential part of Bath’s history and a landmark of industrial archaeology – was about to be lost.

For these were the stone workings that supplied the material used to construct the elegant public buildings and stately terraces that defined Bath in its Georgian heyday: John Wood the Elder’s Queen Square (1728-1736), the North Parade (1740) and South Parade (1743-1748), and The Circus (1754-1768), inspired as much by Stonehenge as the ancient Roman Coliseum, and John Wood the Younger’s Royal Crescent (1767-1774) and the Bath Assembly Rooms (1769).

left This detail from an anonymous painting from 1735 called The Four Worthies of Bath shows Ralph Allen (seated) and Richard Jones, the Clerk of Works who replaced Wood as builder-surveyor of Prior Park.
This detail from an anonymous painting from 1735 called The Four Worthies of Bath shows Ralph Allen (seated) and Richard Jones, the Clerk of Works who replaced Wood as builder-surveyor of Prior Park. Image: Building of Bath Collection, www.bath-preservation-trust.org.uk.

Their client was Ralph Allen (1693-1764), whose vision to revive the ancient Roman spa at Bath was achieved using the wealth he acquired when he took over the loss-making postal service of his day and turned it into a hugely profitable venture – for his own benefit, as well as for that of the state. Fortunately Allen was a philanthropist. He not only built his own trophy house – Prior Park, begun in 1734, now a school set in landscaped grounds managed by the National Trust – he also founded Bath’s Mineral Water Hospital in 1738 – now an NHS hospital specialising in rheumatic diseases – thus setting Bath on the road to growth and posterity on the basis of the healing properties of the town’s mineral water.

The hospital was built using stone from the Combe Down quarries that Allen had purchased when he decided to build Prior Park. These were already being worked in a small way, producing a few hundred tons of stone a year – enough to build just a few houses. Now the postal entrepreneur set about scaling up the production of the mines and turning Combe Down into a major commercial venture.

below A row of 11 cottages built by Allen for his imported labour force in 1729-1730, the origins of the village of Combe Down.
A row of 11 cottages built by Allen for his imported labour force in 1729-1730, the origins of the village of Combe Down. Photo: Oxford Archaeology/Lynn Willies.

Allen adopted the technique then known as ‘undermining’ to get direct access to the best stone by driving adits into the hillside, rather than the more traditional surface mining that had supplied the rubble stone used for the buildings of the Bath area until then. Though coursed rubble stone was still useful for constructing the backs and sides of Bath’s buildings, the desire for smooth façades with no visible mortar joints, imitating the marble and stucco of Venetian palace architecture, could only be achieved by going underground in search of the oolitic freestone.

above Put it on the slate: graffiti in Allen’s quarries record tallies for the price of stone, and workers’ tabs at nearby pubs.
Put it on the slate: graffiti in Allen’s quarries record tallies for the price of stone, and workers’ tabs at nearby pubs.

Leaving the surface intact also meant that it remained available for grazing and for building, increasing the overall value of the land. Allen took advantage of this to build cottages above the mines for his key workers (thus establishing the future village of Combe Down), some of whom were brought to Bath from Yorkshire for their mining skills and had difficulty finding lodgings elsewhere in the area, being resented by the somewhat conservative local masons who were initially resistant to new stone-working practices.

Tension between boss and worker is part of mining culture, and when OA began their recording of the mines they found plenty of evidence for this in the form of graffiti demonstrating the miners’ uncomplimentary attitudes to their employers. The graffiti were incised into the smooth walls of the mine, or drawn in soot or charcoal, and they provide crucial dating evidence and an interesting insight into many aspects of the miners’ lives, including the price of beer in the pubs of Combe Down and the relative prices of different grades of stone. Those two figures are more intimately connected than might at first seem likely, for the innovations that were introduced at Combe Downe from the mid-18th century drove down the price of stone and, when this happened, it was the masons and quarry-men who bore the brunt of the cut, in the form of reduced wages.

Going underground

Pinning down the exact nature of Ralph Allen’s innovations was one of the challenges facing the OA team as they began to survey and record this huge underground landscape, with its complex network of rock columns and cartways, working faces, dressing areas, and spoil heaps. Identifying Allen’s early workings was made easier once it was realised that they were distinguished by so-called ‘apophygate’ columns, which have a small, concave outward curve at the top of the pillar where it joins the roof, and a second type that used a stepped corbel to spread the weight of the roof. This led the survey team to discover one of Allen’s key innovations: where traditionally a single cartway led from the mine entrance to the working faces, Allen had two pairs, making four in all, allowing for a big increase in the amount of stone that could be extracted from the mine.

below Distinctive stonework: Allen’s quarrying can be identified by apophygate columns, curving outwards at the top (left), and stepped corbels (right), which spread the weight of the roof.
Distinctive stonework: Allen’s quarrying can be identified by apophygate columns, curving outwards at the top (above), and stepped corbels (below), which spread the weight of the roof.

Grooves left by cables rubbing against the floor of the roadways showed that each of the four shafts was equipped with a crane for hauling stone or wagons from the quarry face. The cartways themselves were some 2m to 3m wide and 5m high, passing between the rock pillars left to support the roof and lined either side by worked out ‘rooms’, where spoil was piled up, held back by rubble walls. The working faces themselves were stepped to create ‘benches’. Starting at the top, opening up a gap between the freestone and the mine ceiling, wedges were driven into the natural joints in the stone and levers used to pull the stone blocks from their bed.

Some of this stone was roughed out into the sizes and shapes needed by Bath’s architects to reduce the weight of the block before it was lifted by crane onto carts or wagons and winched to the mine entrance. At the mine entrance, the stone was loaded onto the wagons of a wooden gravity railway that led 1.5 miles downhill to the Avon Navigation, where further cranes were used to load the stone onto barges for transport to Bath and beyond.

Tools of the trade: a quarry crane (left) from Union quarry at Odd Down, and (above) grooves left by the cables that hauled stone to the surface.
Tools of the trade: a quarry crane (above) from Union quarry at Odd Down, and (below) grooves left by the cables that hauled stone to the surface. Image: Oxford Archaeology/Lynn Willies.

Simple as all this sounds, it had a huge impact on productivity, as four shafts combined with an integrated transport system meant that stone could be extracted and moved in much larger quantities than before, with a big reduction in transport costs. Account books show that the mines were producing a prodigious 20,000 tons per annum in the peak years when Bath was being constructed, from around 1730 to 1764. Allen himself was deeply involved in the business. The rich and fashionable people of the day were lavishly entertained at his Prior Park home, where the glorious mansion, right down to its Palladian bridge, was a living advertisement for the versatile qualities of the Combe Down stone.

Rock and a hard place

Allen’s contemporaries, seeing his stone everywhere in Bath, naturally assumed that he made a second fortune from the business, but historians working as part of the OA research team believe there is reason to doubt this. Allen invested a huge amount in equipping the quarries with cranes, building his railway and in designing a roll-on-roll-off barge system for getting stone from the waterways onto carts for delivery to building sites all over the city. As the sole user, Allen bore the cost of all this himself, unlike later canals, railways, and turnpike roads that were jointly funded ventures, earning an income for the shareholders from a multiplicity of users.

above This detail from Samuel and Nathaniel Buck’s The South East Prospect of Bath shows Allen’s stone yard and wharf at Dolemead, beside the Avon Navigation, in 1734. The large buildings nearby are a brewery.
This detail from Samuel and Nathaniel Buck’s The South East Prospect of Bath shows Allen’s stone yard and wharf at Dolemead, beside the Avon Navigation, in 1734. The large buildings nearby are a brewery. Image: Building of Bath Collection, www.bath-preservation-trust.org.uk.

His investment meant that Combe Down stone could be transported cheaply and easily to Bath, but his hopes for exporting the stone beyond Bath were greatly hampered by his inability to find ships to transport the stone. Britain was at war with France and coastal shipping was disrupted because crews had all been pressed into service with the Royal Navy or were operating as privateers, going after vulnerable French ships. Allen won a £1,700 contract to supply stone for the building of St Bartholomew’s Hospital, in London, but lost £2,500 in penalty payments when he was unable to deliver. Allen was too far ahead of his time – the Kennet and Avon canal was still 50 years away – and his stone business remained stubbornly local.

It is likely that the Combe Down quarries were heavily subsidised by Allen’s postal income, and when this ceased at his death in 1764, severe cash-flow problems led the heirs to his estate to undo all his innovations: his railway was dismantled, and all the mines cranes, chains, and ironwork were sold at auction. The mines themselves were leased or sold to independent quarrymasters, who reverted to horse and cart transport, leading local people to complain bitterly about the damage this caused to local roads.

A cartway in north-east Byfield Quarry, with likely traces of impressions from horses’ hooves.
A cartway in north-east Byfield Quarry, with likely traces of impressions from horses’ hooves.

But the building industry in Bath continued to boom, with John Wood the Younger now in charge of several large-scale projects, and output continued to be high. Archaeologically, this period is marked by the diversity of working styles, with different pillar systems for roof support and different depths of working, including the very deep section of the mine, dubbed the Grand Canyon for its impressive 8m working faces, in operation from around 1809 to 1838. Unusually, parts of the Grand Canyon had not been backfilled with rubble and waste from subsequent extraction, so the OA team were able to use cameras and laser scanners suspended from cables or extended out on arms or slides to record the evidence for the working methods. They recorded wheel ruts and barrow runs for transporting spoil, and crowbar marks and holes where wedges had been driven into the bedding planes in the stone to prise the blocks from their beds. Clay tobacco pipes recovered from one end of the canyon provided a sequence of dates for the different workings.

Racy rock art

Just as important in establishing dates for different parts of the mine were the graffiti in the form of initials and dates, surveying marks, and pictures, some of which were the work of miners, while others were left by people visiting the mines once quarrying had ceased. Critical evidence for identifying Ralph Allen’s workings were the graffiti ‘JM 1725’ and the initials ‘RJ’, found nearby and in a similar style, with the letter J in the form of a crossed ‘I’. It is probable that RJ was Richard Jones, who became Allen’s clerk in 1731 and was effectively the manager of Allen’s stone and masonry business. The finest of the images shows a three-masted ship of a type that is probably late-18th century in date and that might have been used on the Avon Navigation for transporting stone.

above You can leave your hat on: Graffiti spanning the 18th to 20th centuries range from sedate ships to somewhat saucier themes.
You can leave your hat on: Graffiti spanning the 18th to 20th centuries range from sedate ships to somewhat saucier themes.

Beer and cigar prices were jotted on some of the pillars, perhaps used by quarrymen who ran up slates in the local pubs for reckoning up what they owed for when pay day came and the landlord demanded payment. Several scantily dressed women were found, one of which has the later name and date ‘Sumsion 1836’ scrawled over it. Also of early 19th-century date is Holly, who can be dated from the style of her bonnet and skirt, but who lacks clothing for the upper part of her body, while a mid-20th-century graffito depicts a scantily dressed ‘Jane’ from the mid-20th-century Daily Mirror cartoon. A graffito of a top-hatted but otherwise naked man probably reflects the class antagonism of the Edwardian era.

To preserve some of the most impressive and socially important graffiti, the OA team became miners themselves: they carefully cut out the piece of rock with the graffiti intact and have now mounted them in specially designed steel frames to protect them and make them suitable for display. Graffiti in less stable areas were removed from the mine using a revolutionary new technique. The rock surface was coated with a rubber solution, which was then peeled from the wall, bringing with it particles of charcoal and soot representing the graffiti in mirror image; this was then transferred to a resin sheet, resulting in an imprint of the graffiti suitable for display.

Below Pulled by two horses, the carriages used on Ralph Allen’s pioneering railway could carry six tons of stone.
Pulled by two horses, the carriages used on Ralph Allen’s pioneering railway could carry six tons of stone.

By 1838, the underground mines at Combe Down were virtually worked out, and the focus of future freestone quarrying shifted to Box and Sherston, in Wiltshire, where the deep mines enjoyed what Ralph Allen had lacked a century earlier: access to roads, canals, and the new railway system connecting Bath to Britain’s growing cities. At Combe Down itself, quarrying continued for a further century, but in the form of surface mines, producing great quantities of cheaper stone dismissed by The Builder magazine (20 April 1895) as ‘gerry-builders’ stone par excellence’.

above Light at the end of the tunnel? Mining at Combe Down petered out in the 1830s but the industry prospered elsewhere in Wiltshire.
Light at the end of the tunnel? Mining at Combe Down petered out in the 1830s but the industry prospered elsewhere in Wiltshire.

Thus ended the first large-scale underground stone workings in England, a brave experiment on Ralph Allen’s part that, like so many pioneering industrial ventures, might be judged a failure by modern-day accountants, especially when the costs of stabilising the mines between 2000 and 2008 to protect the 760 properties that lie above them are taken into account. But this is to separate out the mines from the wider story of the creation of Georgian Bath, in which the mines played such a fundamental part.

Below Gone but not forgotten. Although now filled with concrete, Allen’s innovative mines survive in Oxford Archaeology’s record.
Gone but not forgotten. Although now filled with concrete, Allen’s innovative mines survive in Oxford Archaeology’s record.

Through innovations and efficiencies that increased the level of production and reduced the price of stone, Ralph Allen permitted the vision of John Wood and his son to be realised, removing the temptation to use other materials than the local stone. Had Bath been built of brick or stucco, it might be known today as another pleasing English market town; instead of which Allen’s stone and the Woods’ architecture created the cohesiveness that is such an important feature of Bath’s urban landscape and its World Heritage status.

Further reading
Lynn Willies, Neville Redvers-Higgins, and Ianto Wain (2011) Finished Labour of a Thousand Hands: the archaeology of the Combe Down Stone Mines, OA Monograph No. 13 (ISBN 9780904220605, £25). Available from Oxbow Books.

Acknowledgements
This 11-year archaeological recording project has been successfully concluded thanks to the foresight and funding of Bath and North-East Somerset Council and the Homes and Communities Agency with the excellent support of the main contractors, Hydrock Contracting.
All images: Oxford Archaeology South, unless otherwise stated.