Erimo Volcanic Sand in Hokkaido.

Abstract

The Erimo sand was named by Dr. Y. Ogasawara in 1941 at Erimo in Hokkaido. In 1957 and 1958, present writer found the Erimo sand distributed widely on the terrace surfaces along the coast of Hidaka.The volcanic sand of Erimo is deposited on the higher and lower coastal terraces as well as on the higher river terraces along the Hidaka coast. Stratigraphically it continues to the Shikotsu pumice deposit, erupted from the Shikotsu volcano in the late Pleistocene at Bibi and in its neighbourhood. The author examined 34 columnar sections (Fig. 2), and analysed the grain size and heavy mineral composition (Fig. 3, 4). According to his observations, the volcanic sand of Erimo has the same origin as the Shikotsu pumice deposit.An embedded fossil forest was discovered at Bibi and in its neighbourhood, and its absolute age was decided by C14 methods. The volcanic sand of Erimo covers the Mammontius bed correlated with the lower terrace deposit at Ogoshi. The abovementioned relations exit also in the south of Tokachi plain. Consequently it is considered that the terraces of Hidaka coast and Tokachi plain are correlated each other geomorphologically.