Mull, Iona and Ardnamurchan: Landscapes in Stone

Lying off the south-western tip of Mull, the island of Iona has huge significance as the first important centre of Christianity in Scotland. But the Abbey itself is built upon rocks that tell of events of much greater antiquity: the Lewisian gneisses of western Iona are some of the oldest rocks in the world. Alan McKirdy explores the fascinating geology of the area.