CN416

Penrhyn Quarry: relict areas, quarry hospital and underground levels  

20/08/2021  

Designated  

Gwynedd  

Llandygai  

262252  

364769  

Industrial  

Quarry  

Industrial  

The monument comprises the relict remains of Penrhyn Quarry along with its quarry hospital and underground haulage and drainage system. Situated on the north slopes of Mynydd Elidir southwest of Bethesda, the quarry exploits the Cambrian slate formation of the west flank of the Ogwen Valley. The quarry has remained in constant use for more than 200 years and at one time represented the largest manmade excavation in the world. Active quarrying continues around the scheduled area today. Penrhyn Quarry is 16th century in origin but major exploitation began in 1782 under Richard Pennant, the first Lord Penrhyn. As a hillside quarry, Penrhyn pioneered gallery working under Benjamin Wyatt who became estate manager in 1799. Over the following 100 years the benched galleries extended into a massive quarry pit as production expanded to meet the international demand for roofing slate. By the end of the 19th century, the quarry was the most substantial undertaking of the North Wales slate industry regularly producing more than 100,000 tonnes of slate per annum and employing nearly 3000 men. Strict management of the quarry led to the development of an elaborate quarry plan, arranged with defined areas for extraction, processing and tipping. The Ordnance Survey third edition map (1914) illustrates galleries with blast shelters and working levels with large numbers of gwaliau for hand splitting. All of the working areas interconnected using counterbalance inclines and a complex internal rail system leading out to slate waste tips to the northwest and southeast. Utilising innovations more common to the coal mining industry, water balances were used extensively at Penrhyn to haul rock from the base of the increasingly deep quarry pit. Penrhyn Quarry was both innovative and influential, many of the developments at the quarry later being used elsewhere, in other quarries across Gwynedd and further afield. The Penrhyn Quarry Railroad (CN415) which connected the quarry to the harbour at Porth Penrhyn in Bangor was the first of its type in the industry. The first on-site Quarry Hospital was also developed at Penrhyn between 1840-42. While the process of ongoing quarrying during the 20th Century has led to the loss of physical functional connections, several coherent and well-preserved relict areas remain intact. The designated area is divided into five parts: Penrhyn Quarry Hospital (Area A), Penrhyn Quarry processing area (Area B), Galleries (Area C), Southeast tips (Area D) and Penrhyn Quarry underground drainage and haulage levels including water balance shafts and head frames (Area E). Area A: Penrhyn Quarry Hospital. The Quarry Hospital (Yspytty Brynllwyd) was built in 1842 and contained three wards, a surgery, and a waiting room. It was a very early adopter of anaesthetic with an amputation carried out under ether in 1847. The ruined remains of the hospital survive in woodland to the east of the modern quarry and north of the quarry pit. The main building is a roofless two-storey structure which faces northeast and measures 16m E-W by 11m transversely. The interior is partially filled with collapsed rubble but some internal walls and fireplaces survive intact. The external elevations survive to full height and are part rendered with evidence of slate cladding to the rear. The main hospital building is surrounded by ancillary structures associated with its operation including a mortuary, greenhouses, sheds, and garden paths situated within a large oval enclosure partly defined by a slate slab wall. The west part of Area A includes the location of a rail connection that provided access from the quarry. Area B: Penrhyn Quarry Processing Area. Only a small number of historic working levels survive at Penrhyn. Area B includes all of the remaining levels as shown on the Ordnance Survey first edition map (1889) including ‘Twlldyndwr’, ‘Agor Boni’ and ‘Red Lion’ levels. The infrastructure survives much as illustrated on the Ordnance Survey third edition map (1914). There are several well-preserved features including the relict remains of the Twlldyndwr to Red Lion counterbalance incline, the Red Lion to Twlldyndwr uphaulage incline, weigh house, locomotive shed, railway tunnel, bridge abutments, gwaliau and the remains of a blondin base. Area C: Galleries. The remaining relict parts of the galleried pit that have not been tipped over during the 20th Century. The galleries are a significant landscape feature that contain an area of distinctive sloping slabs, indicating a fault in the slate that can be seen in historic photographs of the quarry. A rectangular revetted platform with dimensions of about 12m x 8m can be seen on one of the upper levels and is probably the base for a chain incline. Area D: Southeast Tips. This relict area of tipping mostly dates to the period of peak output towards the end of the 19th century and survives unaltered since the production of the Ordnance Survey third edition map (1914). It retains branching tipping runs, tipping cobs and several small shelters. Area E: Penrhyn Quarry underground drainage and haulage levels including water balance shafts and head frames. Due to the depth of the quarry pit at Penrhyn a complex system of underground haulage levels were excavated to connect the lower galleries of the quarry pit with the surface processing areas via eight water balance shafts. The water balance system utilised vertical shafts with mechanical head-frames, in which tanks surmounted on cages were filled with water at the top of the shaft and emptied at the bottom, their superior weight hauling up an empty tank, attached to which was a fully loaded waggon. These were constructed at Penrhyn Quarry after a drainage adit was driven between the quarry hole and Tan Ysgafell between 1845 and 1849. The drainage adit and all of the associated shafts are well preserved. The shafts and haulage levels are no longer used but the drainage adit still serves its original function by connecting the quarry pit to an outfall on the Ogwen River some 1.9km north. Belowground survival of artefacts relating to haulage and drainage is excellent. ‘George’ level retains a well-preserved, in situ, double-track railway system including points and point levers, while the pump chamber preserves an impressive hydraulic engine. Aboveground are two well-preserved head-frames, including tanks and cages. 'Sebastopol', constructed in 1858 was supplied by DeWinton's Union ironworks in Caernarfon while 'Princess May', was built in 1895 by Radcliffe's of Hawarden, a firm which supplied machinery to mining concerns all over the world. The monument is of national importance as a well preserved relic of the slate quarry industry and for its potential to enhance our understanding of the industry. The quarry has remained in constant use for more than 200 years and while the process of ongoing quarrying has removed much of the earlier evidence, several well-preserved relict areas remain intact, demonstrating a wide range of quarry structures and their functional relationships. The quarry also includes rare survivals such as the first quarry hospital and two very rare water balance headframes. The scheduled area comprises the remains described and an area around them within which related evidence may be expected to survive. The scheduled area is divided into 5 parts: Area A is an irregular polygon c.140m N-S by c.100m transversely centred on NGR 262450, 365796. Area B is an irregular polygon c.450m N-S by c.220m transversely centred on NGR 261968, 365160. Area C is an irregular polygon c.330m NE-SW by c.150m transversely centred on NGR 262252, 364769. Area D is a large irregular polygon c.900m NE-SW by c.400m transversely at its widest point, centred on NGR 262701, 364593. Area E is a complex of inter-connecting linear polygons representing the underground drainage and haulage system laid out between NGR 262150, 365090 and 261560, 366860.