Examining volcanic materials in deep sea sediments may be one of the most important tasks of the Deep Sea Drilling Project. The investigation of volcanic ash near young source volcanoes is particularly helpful in enabling us to infer the history of volcanism in and around the island arcs. In the area of the Japanese islands volcanic deposits are usually distributed east of the source by prevailing westerly winds. It is also possible that some deep sea tephra has its source in a large, already known land volcanism.

Supplement to: Furuta, Toshio; Arai, Fusao (1980): Petrographic properties of tephras, Leg 56, Deep Sea Drilling Project. In: Scientific Party, Initial Reports of the Deep Sea Drilling Project, 56/57 (eds.), Initial Reports of the Deep Sea Drilling Project (U.S. Govt. Printing Office), 56-57, 1043-1048