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
Chwarel y Fan Monmouthshire. The summit is on a thin ridge and is crowned by a cairn. On the other sides of the valleys: to the west is Pen Twyn Mawr and to the east is Black Mountain. Chwarel y Fan Chwarel y Fan is a peak in the Black Mountains in south-eastern Wales. It is the highest rise on the long ridge which extends southeastwards from Rhos Dirion. The ridge continues southeastwards to the lesser summit of Bal-Mawr whose top is adorned by a trig point at above sea level. A further 1 km southeast along the ridge is the lesser top