Historic Landscape Characterisation

Arfon - 11 Dinorwic, Marchlyn, Gallt y Llan slate quarries and Llanberis copper mine


© Crown copyright. All rights reserved, Gwynedd Archaeological Trust, 100017916, 2005

Historic background

The main part of the Dinorwic slate quarry complex, at one time the second largest in the world after Penrhyn Quarry. Earlier workings were to the north of this area (see 08) but there is evidence for some working on the present site of the main quarry from 1787. In the course of the nineteenth century these workings were united to form the different departments of Dinorwic quarry, and contour railways and inclined planes laid to connect the rock face with the tips, the slatemakers’ shelters and the mills. The quarry closed in 1969, and part of the lower workings around Hafod Owen have been substantially altered to create the pumped storage scheme.

The adjacent Marchlyn quarry was opened in the 1930s on a greenfield site and was developed after the second war using modern methods. It closed down in the 1960s.

The copper mine may be bronze age in origin, and was active by the mid 18th century . Operations ceased in the 1870s.

Gallt y Llam quarry was operative from c.1811 to c. 1832 but was never developed on the scale of Dinorwig.

Key historic landscape characteristics

Slate quarry and copper mine landscape

Dinorwic quarry is a visually spectacular site covering a considerable area. Worked as a galleried open quarry, the galleries themselves survive largely intact as do the substantial dry-stone incline embankments built to connect the different levels. In a number of locations the shells of the slate mills erected from 1921 onwards survive. Though the complex of buildings at steam mills level (‘ponc ffeiar injan’) have been demolished, the upper levels of the quarry retain most their machinery, including railways, inclines, ropeways, saw tables and compressors.


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