Site Record

Ffridd-glyn (or Cambrian) Slate Quarry is located above and to the west of Llanberis. It comprised a 'hotch-potch' of small workings operating from the mid-nineteenth century in conjunction with Goodmans Quarry (SH572606), both amalgamating with Cefn Du (NPRN 400667) in 1878. There was a tramway connection to the Ffridd incline, single acting with a steam haulage that replaced an earlier water turbine.
This quarry saw the introduction from America, in 1872-3, of the Burleigh Drill, a percussive drill in which the bit was moved by the action of a directly connected piston in a cylinder, actuated by steam or compressed air. It cut through slate at a rate of about 0.6 metres per minute. However, the quarry found that they were ill-suited to confined spaces and often broke. It was reported that the drill derived `its mobility from a steam engine which is situated on a crag in the quarry, to excavate rocks from a lower gallery?.
Output from the quarry was about 1000 tons per annum. By 1898 the workforce numbered only seven though the quarry continued operating at least until 1919.
Visible remains (in 1991) include pits, a network of tramway formations and rubbish runs, several collapsed tunnels and ruins of buildings, one a possible steam-powered mill.

Sources:
D.Gwyn, Welsh Slate: the Archaeology and History of an Industry (RCAHMW 2015), pp.69 & 89.
A.J.Richards, A Gazeteer of the Welsh Slate Industry (1991), p.31.
OS County series 25-inch map: Caernarvonshire sheet XVI.8, editions of 1889 & 1900; six-inch 16NE, 1919-20 edition.
Air photos: RCAHMW AP94-CS 1026; AP945131/51

David Leighton & J.Wiles, RCAHMW, 15 January 2015