The World Around Us

Pen y Fan, Brecon Beacons. The summit is composed of rocks dated some 10 million years later than the sandstone immediately below it but there is little evidence of the erosion to be expected over such a period of time.

Pen y Fan, in the Brecon Beacons National Park At 886 metres (2907 feet) above sea-level it is the highest peak in South Wales. It is formed of various units of the Devonian Old Red Sandstone. The summit is composed of the Plateau Beds Formation, dated some 10 million years later than the sandstone immediately below it. The junction however shows little evidence of the erosion to be expected over such a period of time.

Credit: Dave Dunsford