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Porthgain quarry works
Porthgain, Pembrokeshire, Wales, UK
associated engineer
Not known
date  c.1850 - 1931
UK era  Victorian  |  category  Mining/Quarrying  |  reference  SM806327
Porthgain is a coastal hamlet on St David’s peninsula in north Pembrokeshire in Wales. It hides an industrial past, once exporting slates, bricks and road stone from its harbour. Today it is a popular tourist destination.
Increasing industrialisation and demands for housing in the first half of the 19th century led to the transformation of Porthgain from fishing village to industrial centre. Porthgain's small, deep but naturally sheltered harbour was constructed in 1851, on land released by the Crown Estates Commissioners. Its primary purpose was the export of slate.
Slate had been quarried from the regions either side of Porthgain long before the harbour was built. In 1838, the Barry Island Farm Quarry undertook slate quarrying at Abereiddi (SM795315) to the west of Porthgain, though it is likely that slate had been mined there before. In 1841, the Abereiddi quarry lease passed to the London-based syndicate of Benjamin Hill, Robert Norman and John Barclay. The trio also began operations at the much older (c1800) quarry of Trwynllwyd (SM832329) to the east. The three quarries were run as a unit thereafter.
In Porthgain itself, slate had begun to be quarried from the land above the town (SM812324), and probably in other locations, on or before 1850. A drainage tunnel was later constructed due north from the quarry pit to the cliff face.
In 1851, a 3.1km long horse-drawn tramway was constructed between Abereiddi and Porthgain. Small vessels brought slate by sea from Trwynllwyd. So slate from all three locations was exported from Porthgain Harbour and the returning ships brought in coal, culm (anthracite dust and chippings) and lime.
In 1855, control of the quarries passed from Hill, Norman & Barclay to the Barry Island Slate & Slab Co. By 1859, slate was being cut to size at the mill in Porthgain. The mill had six saws and two planers, all powered by a 7.3m diameter waterwheel. Abereiddi provided mostly roofing slates, while slate from Trwynllwyd and Porthgain was mainly slabs (for windowsills, lintels, doorsteps, mantelpieces and so on).
After such a promising start, the Barry Island Slate & Slab Co went bankrupt in 1860 and its property was sold. The sale particulars show that Porthgain then had three or four horse whims (horse-powered winding engines), a horse-powered pump, a slate yard on the tramway and 14 cottages for quarrymen.
Porthgain slate quarry reopened in 1862 under the management of Englishmen J.F.N. Hewett and A. Grierson. Two years later, in partnership with John Davies, they formed the St Brides United Slate & Slab Co to operate the three quarries. The company invested in new machinery, including a 12kW Robey engine on a chain incline, and relaid the tramway between Porthgain and Abereiddi as a railway. In October 1869, the company went into voluntary liquidation.
John Davies obtained the lease on Porthgain quarry in 1875, forming the St Brides Welsh Slate & Slab Co. A new 15kW Hazeldine engine was installed to power the slate mill when the water supply was insufficient to drive the waterwheel. Unfortunately by 1880, the company was bankrupt — a victim of the collapse of the slate market two years earlier.
In 1883, work restarted at the Porthgain slate quarry, overseen by the newly formed United Welsh Slate Co Ltd Production increased and a new boiler was installed to improve the performance of the mill engine. Slate was transported to the harbour by horse-drawn trucks running on tramways. From the 1880s, when the quarry was much deeper, tramways were laid through underground tunnels from the quay (SM814325) to various pits for extracting slate.
Though the slate was not of the best quality, being sold some 20% below market value, it had a secondary use. From 1889, slate waste from the quarry was made into red bricks. A 137m long tunnel was driven from the slate quarry to the quayside, enabling the slate waste to be brought directly to the brick works — the tunnel entrance can still be seen in the bottom of the quarry. Up to 50,000 bricks per week were made in a large stone building facing the centre of the harbour (SM814325). The building survives as a restaurant.
Like so many of its predecessors, the United Welsh Slate Co Ltd had financial problems. In 1889, control of the quarry at Trwynllwyd was reclaimed by its landlord, J. Beynon Harries, depriving the company of its best quality slab slates.
As if to compensate, in 1889 rock mining began at a coastal cliff quarry (SM807326) 800m west of Porthgain. As metalled roads became more common, because they resisted wear from the iron-bound tyres on agricultural vehicles, so the demand for sources of road stone grew. Though the Porthgain stone was marketed as granite, it is actually dolerite, a finer grained igneous rock between granite and basalt in appearance.
The invention of dynamite — patented by Alfred Nobel (1833-96) in 1867 — made quarrying the dolerite viable. Material could be released from the rock face by blasting, something that would have been all but impossible with manual excavation.
The two Porthgain quarries were known locally as Jerusalem (granite) and Caersalem (slate), and attracted miners from St David’s and Goodwick — up to 16km away — who walked to work daily.
In 1893, H. Birch formed the Porthgain Granite, Slate & Brick Co Ltd to handle all the mineral extraction in Porthgain. Birch swiftly sold the new company to a group of London investors and started Porthgain Harbour Ltd to develop and manage the town's harbour.
The Porthgain Granite, Slate & Brick Co Ltd survived for two years. In 1897, Porthgain Quarries Ltd tried to begin quarrying again. The harbour and quays were extended in 1902-4, but the tramway from Abereiddi closed in 1906. In 1904, the harbour and quarry companies amalgamated and were acquired by a Bristol company who operated through its subsidiary United Stone Firms. The slate and brick trades ceased soon afterwards, in 1910 and 1912 respectively, though the road stone trade flourished.
Rock was blasted from the quarry sides with explosives. Men called 'breakers' reduced the slabs to sizes suitable for loading into drams (wheeled metal wagons). Stone was hauled over another tramway laid south east from the dolerite quarry to a steam-powered crusher located at the top of the slope, above the harbour.
The rock was crushed and transported on a tramway to giant hoppers (SM813325) on the west side of the harbour for storage before being exported. Stone was shipped to ports in south Wales, Somerset, Devon, Kent, London and Ireland. In 1909, exports totalled around 4,000 tonnes per month.
The stone was stored in hoppers, or bins, constructed in the locally made brick. Each contained a different size of road stone — from 6mm to 63mm. A main block of 10 hoppers adjacent to the quay contained 406-813 tonnes of stone each. To the north of this block four larger hoppers contained 2,030 tonnes each and to the south an extra storage bin held 203 tonnes. A lower tramway along the quay enabled stone to be transferred from the hoppers to the waiting ships.
Quarry workshops (SM808327) stand at the top of the east side of the quarry. The two steam locomotives for hauling the drams had an engine shop (SM812324) just east of the slate quarry. Another building (SM811325) to the north housed a weighbridge. All the buildings are of Porthgain brick.
The first two decades of the 20th century were busy ones for exporting Porthgain's granite. However, by 1929 production was less than 200 tonnes per day and United Stone Firms was in receivership.
In 1930, the quay was shortened to allow ships up to 660 tonnes to enter the harbour, which dries out at low tide. However, the demand for road stone dwindled as more vehicles started using rubber tyres, which had less grip on metalled roads. The worldwide economic depression compounded the problem, and the road stone trade at Porthgain stopped in 1931.
The closure of the granite quarry was swift and its effects lasting. As Mark Whitby says of it:
"Porthgain closed overnight. The account books were left lying in office, the quarry locomotive in its shed up on the hill, and trucks on the quay, all as if the ice queen had visited. For the few inhabitants who stayed there was fishing and poaching rabbits in a community that worked together. The harbour was taken over by fishing boats, the granite tunnels along the quay turned into stores for lobster pots, and over a number of decades Porthgain transformed from desolation to destination. The silos became perhaps the least ancient of all our listed ancient monuments. The settlement was made a conservation area, and in 1982 all of the industrial property was purchased by a town trust together with the Pembrokeshire National Park authority."
The industrial buildings and remnants of quarrying activities have been designated a Scheduled Ancient Monument, and are part of the Pembrokeshire Coast National Park. In February 2010, a film evoking the past and present uses of the granite quarry went on display in Cardiff.
RCAHMW_NPRN 33206, 34343, 40621, 40728, 40815
Research: ECPK
"My Kind of Town" by Mark Whitby
in Architecture Today, London, 19th June 2011
"The Slate Quarries of Pembrokeshire" by Alun John Richards, Gwasg Carreg Gwalch, Llanrwst, 1998
"About Porthgain" by Tony Roberts, Abercastle Publications, Fishguard, 1987
"Porthgain: Discover the industrial past of this unique village” leaflet funded by the Pembrokeshire Coast National Park Authority and the Welsh Assembly Government, available at http://www.uklandscapeaward.org

Porthgain quarry works