3 Archaeological Excavations on Batan Island Peter Bellwood, Atholl Anderson and Eusebio Dizon Tis chapter identifes a major eruption of the Iraya volcano about 1500 years ago that buried many regions of central and northern Batan Island. It continues onwards to describe the layout of excavations and the stratigraphy revealed in the open sites of Sunget, Mahatao, Naidi, Payaman and Tayid, all buried beneath the Iraya ash. Excavations of post-eruption occupation layers in a number of caves and rockshelters are also described, and it is interesting to note that none of these caves or shelters produced any evidence for very ancient (pre-Neolithic) occupation. Tey seem to have been used mainly for occupation in the late prehistoric period of ijang warfare. Although slightly smaller than Itbayat Island in land area, Batan is the most fertile island in Batanes. It supports most of the population and has the most settlements, including the modern administrative centre of Basco with its airport and harbour. Dumb-bell shaped, the northern part of Batan is formed by the active Iraya volcano (1009 m), the southern by the extinct Matarem (459 m), with the narrow neck between formed by volcanic soils and occasional coastal outcrops of coral limestone (Fig. 3.1). Most of the agricultural activity on the island is focused today across this central neck, roughly from Basco to Mahatao (Fig. 3.2), and around the coastal fanks of Matarem. Te northeastern and northern coastlines of the island are essentially uninhabited. Not surprisingly, the distribution of known archaeological sites follows the modern distribution of settlements and agriculture very closely indeed. Batan Island: Vulcanicity and archaeology Before describing the archaeology of Batan, it is necessary to examine the recent volcanic history of the island. Te southern volcanic complex, Matarem, is no longer active, but many sites are buried under volcanic ash from a geologically very recent eruption of the northern volcano, Iraya. Tis ash blanket, dated to c.AD 500 (see below), provides a very useful minimum age in central Batan for the sealed archaeological assemblages from hill and ridge top sites, such as Sunget, Naidi, Payaman and Tayid, all discussed below. A geological report on the island by Richard et al. (1986) was the frst to indicate that archaeological sites were buried beneath deep layers of volcanic ash and lapilli derived from Iraya. Tis team collected charcoal of archaeological origin, radiocarbon dated to 2310±80 BP (uncalibrated), from beneath ash and pumice layers at Naidi, near Basco. Wood beneath similar ash beds exposed on west Songsong Beach was also dated to 1700±210 BP. Wood from beneath another fow of coarse-grained basaltic andesite further east on Songsong Beach, closer to the volcano but above stratifed ash beds