Remains of the Cornwall slate quarry are located to the immediate east of Talysarn. The pit workings opened in 1867 though extraction began as early as c.1760, possibly by Cornish copper miners. Material was carried by Blondin haulage to a mill on a rubbish bank. In 1882 output was 1040 tons with 70 men, increasing towards the end of the nineteenth century. The quarry was connected to the Nantlle railway. After 1899 material was tipped south of the river Llyfni by a timber bridge which collapsed in 1827.
In the mid-nineteenth century the quarry became part of Tal-y-sarn (NPRN 402462), and in 1921 was incorprated into the Dorothea quarry (40539).
Source: A.J.Richards, A Gazeteer of the Welsh Slate Industry (1991), p.49.
Site depicted in use on Ordnance Survey County series 25-inch maps: sheet Caernarvonshire XXI.9, editions of 1889, 1900 & 1916.

David Leighton & J.Wiles, RCAHMW, 26 January 2015