The Paleogene Sakurae Group in the central Shimane Prefecture consists of lower rhyolite lavas，andesite lavas，acidic tuffs，acidic welded tuffs，acidic lapilli tuffs and upper rhyolite lavas，in ascending order．Some dikes and plutons−andesite，dacite，felsite，granophyre etc．−are emplaced in the eastern part．An inferred arcuate fault strikes from the south center to the northeast in the mapped area．The welded tuffs，which are predominant in the area enclosed with this arcuate fault，show steeper dips nearer the fault due to drag．