The 12th-century chronicler Geoffrey of Monmouth attributed the building of Stonehenge to Merlin the magician. According to his History of the Kings of Britain, Merlin located the stones on a mountain in Ireland and exercised his special powers to spirit them over to Salisbury Plain. My, how we chortle at the credulity of those nincompoops of long ago!

But had you informed Geoffrey that, in fact, the stones had been conveniently deposited by a moving sheet of ice several million years before Merlin supposedly drew breath, he would probably have responded in a similar fashion, with a great medieval guffaw and the Middle English version of ‘Pull the