Some like it hot

In the mid-6th century, legend has it, St Brendan set off from Ireland with a currach-load of monks on a mission to find the Isle of the Blessed. The Irish like to think that his Atlantic odyssey took him to Newfoundland before the Vikings; what seems more probable, if you believe the medieval account, is that it brought him close to the shores of Iceland where he passed a mountainous island with ‘a great smoke issuing from its summit’ and ‘flames shooting up into the sky’.

If there were any doubts that what is meant here is a volcano, they would be dispelled by the drawing in the margin of the version of the Navigatio Sancti Brendani Abbatis currently on show at the Bodleian Libraries. This 14th-century manuscript is not the oldest object in the Bodleian’s new exhibition Volcanoes. That honour belongs to a carbonised scrap of papyrus from a private library in Herculaneum buried during the great AD 79 eruption of Vesuvius described by the 17-year-old Pliny the Younger, who survived it. His less fortunate uncle, Pliny the Elder, who bequeathed the name ‘Plinian’ to the particular sort of violent ash cloud in which he perished, is remembered in the show by a Renaissance manuscript of one of his letters.

But this is not an antiquarian exhibition. Its curator is David Pyle, professor of earth sciences at the University of Oxford, and its thesis is that marshalling historical evidence of past explosions is the best way of predicting future ones. When dealing with capricious geological phenomena measured in hundreds, if not hundreds of thousands, of years, the further back in history you can go the better.

Volcanoes have fascinated scientific minds since the early Greek-Sicilian philosopher Empedocles concluded from studying Etna that rather than clinging to a rock, as Boy George would have it, humanity was sitting on a hot potato.