Photo of the Week

Across the Ogwen valley from Pen yr Ole Wen 978m is one of the most majestic mountain amphitheatres of Snowdonia. Cwm Idwal is the epitome of a glaciated valley and in 1831 drew Charles Darwin to investigate what would become his world famous but controversial publication On The Origin Of Species. He noticed that the scattered boulders of Cwm Idwal held tiny fossils of Silurian sea creatures and oceanic plant life; clues to their previous incarnation as the rocky floor of the Lepetus Ocean. He and fellow geologist Adam Sedgwick returned a decade later to realise their second important finding that the landscape here had been carved by ancient glaciers.

Photograph by Lee Evans