1.

The Prince of Wales slate mine is located at the head of the Dwyfor valley to the north-east of Dolbenmaen. It was an old open working, finished product being carried to Rhyd Du, followed by some development in the 1860s when perhaps three levels were worked. It was worked more intensively in 1873 when the extension of the Gorseddau Tramway to the site gave ready access to Porthmadog. Further levels were started until seven were operating, all connected by a single main incline. Some underground working took place on three levels. A water-powered mill (NPRN 287785) was built at the new terminus of the Gorseddau Tramway. The mill dealt only with slab, reduction of roofing slate taking place on the terraces. At its peak the quarry employed 200 men producing 5000 tons per annum. The quarry closed in 1886 but some small-scale working continued until 1920.

Sources:

• D.Gwyn, Welsh Slate: the Archaeology and History of an Industry (RCAHMW 2015), pp.112 & 120.
• Ordnance Survey County Series 25-inch maps: sheet Caernarvonshire XXVII.3, editions of 1889, 1900 & 1915.
• A.J.Richards, A Gazeteer of the Welsh Slate Industry (1991), pp.101-2.

David Leighton, RCAHMW, 26 February 2015      

2.

A relict slate quarry in the Tan yr Allt slate of Ordovician age, worked from the 1860s to 1881, illustrating working-practices from the industry’s height, and technologies imported by a manager from Penrhyn Slate Quarry in the Ogwen valley. The poorly-cleaved rock of Prince of Wales produced significant amounts of slate-slab, sawn at a mill at the foot of the main incline. 

The quarry is worked partly by means of open levels, shafts sunk on working floors and opened out laterally and partly by limited underground chambering accessed by adits, in a poorly-cleaved and faulted vein of slate. The remains of buildings on each working level include slate-makers’ shelters, blast shelters, barracks, weighbridge houses and an office. Internal movement was carried out by railways on the levels, connecting to counterbalance inclined planes to the water-powered mill where raw blocks were processed into slabs.  The water-supply to the mill water-wheel pit is evident as a row of dilapidated launder stone piers supporting a now-vanished launder deriving water from a reservoir impounded by a substantial dam.  

STATEMENT OF SIGNIFICANCE: 

Prince of Wales Slate Quarry is a relict landform with a short-lived working history, like its neighbour Gorsedda Slate Quarry (NPRN 40557), and clearly demonstrates slate-working methods from the later years of the slate boom, from 1864 to the 1870s. The hand of William Francis, manager of Penrhyn Quarry (NPRN 40564) is evident in the organisation of its inclined planes and the water-powered slate-slab mill of 1864, which represents in experimental form the design Francis carried out at Felin Fawr (NPRN 570) shortly afterwards. The well-preserved row of slate-makers’ shelters show the element of craft-skill needed to split the rock, and the row of cottage barrack buildings illustrate the difficulty in attracting labour to a remote but beautiful site where industrial development was short-lived.  

This site is part of the Slate Landscape of Northwest Wales World Heritage Site, Component Part 4: Gorseddau and Prince of Wales Slate Quarries, Railways and Mill. Inscribed July 2020. 

Sources: 

• Louise Barker & Dr David Gwyn, March 2018. Slate Landscapes of North-West Wales World Heritage Bid Statements of Significance. (Unpublished Report: Project 401b for Gwynedd Archaeological Trust) 
• Tirwedd Llechi Gogledd Orllewin Cymru / The Slate Landscape of Northwest Wales. Nomination as a World heritage Site (Nomination Document, January 2020) 
• Wales Slate World Heritage Site https://www.llechi.cymru/  

Hannah Genders Boyd, RCAHMW, January 2022