Parc quarry is located between Penrhyndeudraeth and Croesor. Opening in 1870, it was a compact underground working. Material was brought from the adit (possibly using water-powered haulage) to a water-powered mill. Finished product, almost exclusively slab, was taken by a short incline to a bridge across the Afon Croesor, then by a further short incline to make a junction with the Croesor Tramway at the foot of the Lower Parc incline. The quarry closed in 1920 but latterly had been operated in conjunction with Croesor quarry (NPRN 40539).
Remains (in 1991) included several building either in re-use or in good condition (the ornate manager's house still occupied); also, inclines and tramway formations along with the collapsed adit which led to extensive underground chambering, and the ruined mill with its water control system.
Sources:
A.J.Richards, A Gazeteer of the Welsh Slate Industry (1991), 117-8.
D.Gwyn, Welsh Slate: the Archaeology and History of an Industry (RCAHMW 2015), p.110.

RCAHMW, 23 February 2015