Ty'n y Bryn slate quarry is located on the south side of the Lledr valley, close to Dolwyddelan. It began in the 1860s but may have had much earlier origins. It was out of use by 1889 but was operating again by 1900 (Ordnance Survey mapping). The quarry was a pit on four levels connected by inclines to a water-powered mill which, by 1875, was also processing material from the nearby Penllyn quarry (NPRN 420893). Sand saws were used and possibly Hunter saws too. Originally material was carted to Trefriw for shipment, but later a siding from the main line railway was built; this was the only quarry in the Conwy area to have direct rail connection. Output may have neared 2000 tons per annum (including Penllyn). In 1898 only eight men were employed. The quarry closed in the 1930s.
Principal remains (in 1991) include four inclines with ruined drumhouses, several dressing sheds and other buildings. Also, the remains of a weighing machine, wheel-pit and machine bases. There are also vestiges of the tramway and incline from Penllyn and to Dolwyddelan station.
Sources:
OS County Series 25-inch map: sheet Caernarfonshire XXIII.11, editions of 1889, 1900 & 1913.
A.J.Richards, Gazeteer of the Welsh Slate Industry (1991), p.81.

RCAHMW, 16 March 2015