Cwm Ebol quarry is located on the north-east slopes of Cwm Ebol, about a mile to the north-west of Pennal. Extraction was from open pits. Originally several pit workings were connected by an incline to a dressing area. Later, a water-powered mill and a new, substantial stone incline were built, later replaced by a tramway and a third, shorter incline. Material was originally removed by cart; later a tramway took it to a shipping point on the river Dyfi. Much of the product was presumably slab since buildings close to the foot of the incline in the valley bottom are captioned 'Cwm-ebol Slate Works' on early maps. Output in 1883 was 260 tons with nine men. By 1898 only 12 men were employed. The quarry is cited as an example of workings that failed to provide a return on the capital expended.
Visible remains (in 1991) include a substantial mill and other buildings, incline formations, and a reservoir above the site, now dry. A notable feature is the traceable tramway formation to the Dyfi at SH702996.

Sources:
Ordnance Survey County series 25-inch maps: sheet Merionethshire XLVII.10, editions of 1888 & 1901.
A.J.Richards, A Gazeteer of the Welsh Slate Industry (1991), p.168-9.

David Leighton, RCAHMW, 26 January 2015