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 Gaer Pen y Gaer Pen y Gaer (or Pen-y-gaer) is the location of a Bronze Age and Iron Age hillfort near the village of Llanbedr-y-Cennin in the Conwy valley, Wales. A natural defensive site, it had a long history of occupation, indicated by the complexity of the defences, which were amended over time. There are two Bronze Age cairns on the north-west slope, and extensive prehistoric and later field systemsare nearby. The remains as seen today are mostly of Iron Age origin, but further earthworks, probably of medieval origin, lie on the south-eastern slopes. The remains of the two walls of