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 - in particular the eruption of two major volcanoes around
60 million years ago whose magma chambers formed the spectacular hills
and glens of the Ardnamurchan peninsula and Glen More on Mull; and the
Ice Age, when glaciers ripped away much of the upper part of the two
volcanoes and sandpapered the landscape to create the rounded contours
we see today.