Corn Du the last ice age by ice scouring out hollows below the peaks, the water being partly dammed by moraines of rock debris carried down by ice action subsequent to plucking and frost shattering. Corn Du Corn Du is a mountain immediately to the southwest of Pen y Fan and the second highest peak in South Wales at 873 m (2,864 ft), situated in the Brecon Beacons National Park. The summit itself is marked by a well structured Bronze Age cairn with a central burial cist like that on nearby Pen y Fan. The two summits are visible from great distances
Pen-y-cae, Wrexham the Primitive Methodist chapel in Copperas. Coal was extracted from pits at Plas Bennion, Wynn Hall, Afon Eitha, Cristionydd, Groes and Plas Isaf; zinc was worked at Copperas. The area descending towards Acrefair was known as "The Delph", it was served by extensions of the Ruabon Brook Tramway but these were mostly defunct by the mid-20th century. Most inhabitants find employment outside the village in Wrexham with only a few local shops or public buildings providing jobs. "Dee Valley Water" operates two reservoirs in Pen-y-cae: "Pen-y-cae Upper" and "Pen-y-cae Lower". Wright & Son, ran a bus service from Pen-y-cae to