Dorothea Quarry is one of the iconic slate quarries of north-west Wales. Opened in 1829 it was originally comprised of a number of smaller quarries that eventually came together to form the giant excavation that is visible today. Its developement can be traced in the series of Ordnance Survey maps that cover the period, including the County Series sheets Caernarvon. XXI.9 from 1889, 1900 and 1916. The quarry ceased operating in 1970.
There are a large number of surviving buildings on the site including the engine house and restored beam engine (NPRNs 26409 and 33672) and the dressing sheds (NPRN 40541). The Dorothea engine was one of the last to be installed and is the youngest survivor in Britain.
Sources:
Lindsay (1974) 'History of the North Wales Slate Industry' p.318-9
Rees (1975) 'Industrial Archaeology of Wales' p.162, p.166-8.
David Gwyn & Merfyn Williams (1996) `A Guide to the Industrial Archaeology of North West Wales?. Association for Industrial Archaeology
J.Wiles, RCAHMW, 17 June 2004 (edited 3 November 2011).
2.
An incomparably rich industrial-archaeological environment which preserves the most important characteristics of the Nantlle pit quarries, Dorothea Slate Quarry is a landform enclosed by slate tipping which centres on the deep flooded quarry pit. The functional linkages between particular elements within its landform are particularly strong – between the source of the slates, the mills and processing areas, the tips of waste rock raised to higher levels to enable the tips to develop, the chain-incline bastions and powered inclined planes that made this possible, the individual slate-makers’ shelters on the southern tips of the quarry, and the Cornish beam engine which once pumped it out (NPRN 33672)
This site is part of the Slate Landscape of Northwest Wales World Heritage Site, Component Part 3: Nantlle Valley Slate Quarry Landscape. 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 (Unpublished Report: Project 401b for Gwynedd Archaeological Trust)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/
H. Genders Boyd, RCAHMW, January 2022