12 Cwm Croesor and Rhosydd Slate Quarries and Incline System

Historic background


A mountain pass between Croesor and the vale of Ffestiniog which has been very extensively exploited for slate, largely in underground workings though some open pits were also opened. The main sites are Croesor Quarry, Rhosydd Quarry, Wrysgan Quarry and Cwmorthin Quarry. Detailed histories and archaeological studies have been published of Rhosydd and Cwmorthin. Operations continued intermittently from the 1820s to the 1990s; all are currently inactive.
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The history of the quarry and its principal features have been described in detail by Lewis and Denton (1974). In addition, the slate quarrying landscapes of Blaenau Ffestiniog have been studied in considerable detail by GAT, funded by Cadw, and detailed descriptions of individual quarries (and their history) are to be found in the reports listed in section 10.3 of the bibliography.


Key historic landscape characteristics

19th- century slate quarries and incline system

A range of slate quarries which preserve the characteristic elements of working in the Ordovician rock of Merioneth. Rhosydd in particularly as an industrial landscape preserves all the elements of slate exploitation, beginning with outcrop working, pit working and underground galleries. The comparative remoteness of the sites has left many landscape elements comparatively undisturbed, including water-catchment systems such as the syenite dam (SH 6541 4663) which powered the Blaen y Cwm power station, now in reuse. The quarry transport systems largely survive, and include not only the unusual ‘Jacob’s ladder’ incline (SH 6577 4643 – 6537 4608) serving Rhosydd (a Scheduled Ancient Monument) but also the earlier mule tracks, cart-road systems and contour railways. The Wrysgan quarry incline and its tunnel above Tan y Grisiau (SH 6781 4549) are spectacular landscape features < back to the map