dry fog. Plutarch wrote of the sky being on fire near Naples, and Silius Italicus mentioned in his epic poem Punica that Vesuvius had thundered and produced flames worthy of Mount Etna in that year. However, both authors were writing around 250 years later. Greenland ice core samples of around that period show relatively high acidity, which is assumed to have been caused by atmospheric hydrogen sulfide. The volcano was then quiet (for 295 years, if the 217 BC date for the last previous eruption is true) and was described by Roman writers as having been covered with gardens and vineyards, except at the top, which was craggy. The volcano may have had only one summit at that time, judging by a wall painting, "Bacchus and Vesuvius", found in a Pompeian house, the House of the Centenary (Casa del Centenario). Several surviving works written over the 200 years preceding the AD 79 eruption describe the mountain as having had a volcanic nature, although Pliny the Elder did not depict the mountain in this way in his Naturalis Historia: The Greek historian Strabo (ca. 63 BC – 24 AD) described the mountain in Book V, Chapter 4 of his Geographica as having a predominantly flat, barren summit covered with sooty, ash-coloured rocks, and suggested that it might once have had "craters of fire". He also perceptively suggested that the fertility of the surrounding slopes may be due to volcanic activity, as at Mount Etna. In Book II of De architectura, the architect Vitruvius (c. 80–70 BC –?) reported that fires had once existed abundantly below the peak and that it had spouted fire onto the surrounding fields. He described Pompeiian pumice as having been burnt from another species of stone. Diodorus Siculus (c. 90 BC – c. 30 BC), another Greek writer, wrote in Book IV of his Bibliotheca Historica that the Campanian plain was called fiery (Phlegrean) because of the peak, Vesuvius, which had spouted flames like Etna and showed signs of the fire that had burnt in ancient history. Eruption of AD 79 In AD 79, Vesuvius erupted in one of the most catastrophic eruptions of all time. Historians have learned about the eruption from the eyewitness account of Pliny the Younger, a Roman administrator and poet. Several dates are given in the surviving copies of the letters. The latest evidence supports earlier findings and indicates that the eruption