The subsurface geology of the linashigawa Delta, situated in the eastern part of the Shimane Prefecture was examined on the basis of the existing drilled data. A buried valley, which was formed during the Last-Glacial Age. has been covered by prodelta muddy sediments. The valley has the maximum depth of more than 25m below the sea level and the overlying muddy sediments, which were formed during Jomon Transgression, attain to 20m in thickness. The Akahoya (K-Ah) Tephra (erupted 6300y. B. P) is intercalated commonly in muddy sediments of the drilled cores. Its horizon is shown areally in the figure. These muddy sediments are overlain by the deltaic sandy sediments of about 10m in thickness.