“At the end of most streets of Edinburgh's Old Town rises the crimson wall of Salisbury Craigs, a lesson in the unimaginable forces and lapses of time which have gone to shape the world. The Craigs are a basalt intrusion, a fossil tide of volcanic rock which surged through the foundations of a dead volcano some 200 million years ago. Geology and paleontology, with their revelations of deep time and alien life-forms, towered up wherever 19th century Scots turned their eyes. the 'testimony of the rocks' threatened their moral universe, its narrative incompatible with a creation myth or even a creator... Old Edinburgh is shaped like a gigantic lecture theatre with the end wall covered by a chart of the earth's origins.”