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Dinorwic Slate Quarry

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Map ReferenceSH56SE
Grid ReferenceSH5933060580
Unitary (Local) AuthorityGwynedd
Old CountyCaernarfonshire
Period18th Century


Dinorwic Quarry includes the remains of the Braich levels of the Dinorwic Slate Quarry which operated from around 1770 to 1969. Many of the levels remain intact following the construction of Dinorwic Pumped Storage Power Station (NPRN 408885). The series of ‘A’ inclines from Gilfach Ddu (NPRN 40559) and the Anglesey barracks have been scheduled and preserved.

The surviving remains of the site include four substantial counterbalanced inclines, complete with rails, sleepers and drumhouses, a weighbridge house, locomotive sheds, water tanks and an office and caban. There is also a blondin with winding house and an electric compressor house. There is a large slate mill with two integral engine houses and saws, catslide extension and smithing hearth.

In 1972 the site opened to the public as a museum. Equipment was collected from other slate quarries and parts of the site were restored. It is now the National Slate Museum and part of the National Museum of Wales.


  • David Gwyn & Merfyn Williams (1996) ‘A Guide to the Industrial Archaeology of North West Wales’. Association for Industrial Archaeology

RCAHMW, 3 November 2011


Dinorwic quarry is a spectacular relict industrial landform of stepped rock-faces, inclined planes, tips and process-flow, on the slopes of Elidir mountain, rising 500m from the valley floor. It is made up of separate ‘departments’, all of which formed part of the one undertaking owned by the Vaynol estate but which was never entirely assimilated into one unified working, as Penrhyn quarry was. Each department, and the galleries within them, have topical names such as Matilda and Australia, or topographical names such as Penrhyddgarrett. The Vivian department (NPRN 40571) with its reconstructed operational inclined plane, slate-makers’ shelters, and a ropeway system, is separately noted.

Attributes of this component part date from the 1780s to the 1920s within a landscape of aristocratic improvement.

Dinorwic was developed by an aristocratic dynasty (the Assheton Smiths, later the Duff family) of the Vaynol estate, who were also committed agricultural improvers. Dinorwic quarry rivalled Penrhyn in size and output and emulated it in many respects but developed a strongly engineered approach of its own.

The sudden closure of the quarry in 1969 meant that many buildings, structures and machines survived on some of the higher, more remote levels. The very visible nature of the workings when viewed from the slopes of Snowdon or across Peris lake bring home the form and extent of the quarry, and the construction of a major pumped storage scheme in the lower part of the quarry from 1975 to 1984 added to the sense of the ‘engineering sublime’.

This area and the Ogwen valley component part of the proposed site have much in common but also significant points of difference. Whereas part of Penrhyn quarry is active, Dinorwic is entirely relict, and offers both the specialist and the interested visitor a text-book explanation of slate-quarrying practice from the late eighteenth century to the 1960s.

Statement of Significance:

Dinorwic Slate Quarry is a spectacular and extensive relict industrial landform, worked in benched galleries on the slopes of Elidir mountain by the owning Vaynol estate until its sudden closure in 1969. Second only to Penrhyn Slate Quarry in its extent and productivity, it can be appreciated in its entirely from across Peris lake, where the working faces and levels, tips of waste rock and the massive formation of the inclined planes are evident. Several locations within the Quarry, particularly on its upper levels, preserve a wealth of historic engineering and machinery dating from the 1860s to the 1930s. Its functional linkages with its former engineering complex, now the National Slate Museum (NPRN 40559), its road and railway transport systems (NPRNs 546042, 546222), and its social linkages with its surviving barracks (NPRN 275726) and settlements (NPRN 409887) are particularly clear. The road access and service buildings of the pumped storage scheme built in the lower part of the quarry from 1975 to 1984 contribute to the sense of scale, and the quarry landform lies within a powerful mountain and lake environment at the foot of Snowdon that is both ‘Sublime’ and ‘Picturesque’. The medieval Dolbadarn castle conveys the pre-industrial dimension to a landscape heritage spectacularly transformed by the global demand for slate from the eighteenth century to the mid-twentieth. 

Dinorwic Slate Quarry is part of the Slate Landscape of Northwest Wales World Heritage Site, Component Part 2: Dinorwig Quarry Mountain Landscape. Inscribed July 2020.


  • 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

Hannah Genders Boyd, RCAHMW, March 2022

application/pdfRCAHMW ExhibitionsBilingual exhibition panel entitled Y Diwydiant Llechi. The Slate Industry, produced by RCAHMW for the Royal Welsh Show, 2011.