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 Llithrig y Wrach underfoot, or because of the resemblance of its pointed profile to an archetypal witch's hat. It is an outlier of the Carneddau, the higher peaks of which can be reached from Pen Llithrig y Wrach via Pen yr Helgi Du. On its eastern side, the mountain slopes steeply down to Llyn Cowlyd. It may be climbed from the southern side, from Capel Curig or the A5, or from the north-east, from Dolgarrog or Tal-y-bont in the Conwy valley. It is quite prominent when viewed from the north near Llandudno. Pen Llithrig y Wrach Pen Llithrig y Wrach is a mountain