Sixty million years ago, central Arran was the site of one of the largest and most explosive volcanoes ever to have existed in Britain. In the long years since its final eruption, erosion by water and ice have exposed the core of this unique magmatic system. Today, geologists can piece together the exposed fragments of basalt, granite, and volcanic ash to give us an understanding of what this volcano would have looked like, and what it meant for the geological evolution of Scotland.