Pen y Fan same noun "ban", in its plural form "bannau", is found in the Welsh name for the Brecon Beacons: "Bannau Brycheiniog". There is no one standard translation of "Pen y Fan", but 'the mountain's peak' or 'the beacon's summit' are both possible translations. Pen y Fan is formed from various units of the Old Red Sandstone which were laid down during the Devonian period. The lower slopes of the mountain are formed from the sandstones and mudstones of the Senni Formation whilst the upper slopes are formed from those of the Brownstones Formation. The very summit, like that of neighbouring Corn
Pen y Boncyn Trefeilw Y Groes Fagl. Pen y Boncyn Trefeilw Pen y Boncyn Trefeilw is a subsidiary summit of Cyrniau Nod in north east Wales. It forms a part of the Berwyn range called the Hirnantau. It has two tops: Stac Rhos and Pen y Cerrig Duon. Pen y Cerrig Duon is now listed as a deleted Nuttall due to re-surveying. The views from the summit are extensive, if unremarkable due to the featureless, flat moorland surroundings. The summit is marked by a small cairn, is which located only a few metres from a track road that continues on to the pass between