Relax. These very large volcanoes were active between between fifty five and sixty million years ago. They were in Ardnamurchan, Mull, Rum and Skye. Last week a team of thirty three eminent international scientists, led by geologists from the universities of Glasgow and Keele, spent four days studying what is called ‘the Ardnamurchan ring complex’. This is one of the best places in the world for exploring the internal structure of a volcano. The complex lies to the east of Ardnamurchan Point – the most westerly mainland point in the UK – where the hills form clear circles – ring complexes, which are volcanic in origin.

When a major volcano erupts, magma from deep in the earth is thrown into the sky as lava, leaving a circular depression called a caldera. As the lava is hurled skywards, surface rocks around the edge of the hole created then collapse inwards into the depression into the caldera. This had been thought to be how the ring complexes were created but re-mapping work by some of the scientists present last week now indicates that the rings were formed by the collapse of the roof of the magma funnel.

The Ardnamurchan rings are what’s left of the interior of one such volcano, exposed finally by the erosions of the sequence of glaciation and melt.