Pits, adits and come chambering.****

Multiple terraces retain a variety of buildings including weigh houses, dressing sheds, and a barrack block with no fireplace, possibly using portable stoves. The workforce was mainly barrack-based, with no elaborate family accommodation, unlike Gorseddau. The incline is well-engineered, with remains of the upper drum house and traces of two earlier drum houses abandoned during upward extension. Evidence of under-floor leats survives on the lowest level, and adits lead to small underground chambers. The workshop, located behind the reservoir, may have reused an older building. The tramway from the foot of the incline past the reservoir is prominent, and the lower incline drum house remains intact. Remnants of attempts to raise the dam include a short tramway formation. The compact mill at the foot of the incline has attractive archways, a wheel pit, and launder pillars.

Quarrying began modestly in the 1860s, possibly on three initial levels. Activity expanded vigorously in 1873 when the Gorseddau Tramway reached the site, removing the need for carts over the pass to Cwm Gwyrfai. Four additional levels were developed, connected via an extended main incline, and some underground working occurred on three levels. A water-powered mill was built at the new tramway terminus, connected to the incline by an elevated tramway and short secondary incline. At its peak, 200 men worked here, producing 5,000 tons of slate per year. The quarry closed in 1886, but small-scale activity continued sporadically until about 1920. All roofing slate was reduced on the terraces, while slab processing took place at the mill.