Staffa (Norse for staff, column, or pillar island), an island of the Inner Hebrides in Argyll and Bute, Scotland. Staffa lies about 10 km (6 mi) from the nearest point of Mull, and 9 km N. by E. of Iona. It lies almost due north and south, is a kilometre long by about half a kilometre wide, is almost 3 km (1¾ mi) in circumference, has an area of 71 acres, and its highest point is 42 m (135 ft) above sea-level. In the northeast it shelves to a shore, but otherwise the coast is rugged and much indented, numerous caves having been carved out by rain, stream and ocean. There is enough grass on the surface to feed a few cattle, and the island contains a spring, but it is currently uninhabited. During the tourist season it is visited every weekday by boat from Oban. The island is of volcanic origin, a fragment of an ancient stream of lava. In section, the isle is seen to possess a threefold character: there is first a basement, of tufa, from which rise, secondly, colonnades of basalt in pillars forming the faces and walls of the principal caves, and these in turn are overlaid, thirdly, by a mass of amorphous basalt. Only the chief caves have been named. On the south-east coast is the Clam-shell or Scallop Cave. It is 10 m (30 ft) high, about 6 m (18 ft) wide at the entrance, some 45 m (130 ft) long, and on one side of it the ridges of basalt stand out like the ribs of a ship. Near this cave is the rock of Am Buachaille (Scots Gaelic, The Herdsman, from a supposed likeness to a shepherd’s cap), a pile of columns, fully seen only at low tide. On the south-west shore are the Boat Cave and Mackinnon’s or the Cormorants’ Cave. Staffa's most famous cave, however, is Fingal's Cave, a huge sea-cave formed from hexagonal basalt that inspired Felix Mendelssohn's overture.