The Isle of Arran dominates the Firth of Clyde. A favourite haunt of holidaymakers, it is also a place of fascination for the geologist, offering a huge variety of rocks that represent a massive slice through geological time. From the ancient bent and buckled strata of Dalradian - a small fragment of the roots of the once mighty Scottish Highlands - the dramatic Northern mountains through which ice gouged its way during the Ice Age, to the relatively...