Marine Terraces of Rebun Island, Hokkaido

Abstract

Rebun Island is situated off the northwestern coast of Hokkaido, Japan. There are three erosion surfaces in this island, and their apporoximate heights are 300m, 20m, and 160m.There are also three marine terraces-Kahuka Terrace, Benzaidomari Terrace, Horodomari Terrace in this island, and their approximate heights are 120-100m, 80m, and 40-30m respectively (Fig. 3).The writer found that these terraces are widely developed both in the northern and southern parts of the island, but they were less remarkable in the central parts. At the Kaneda Cape and the Sukoton Cape situated in the northernmost districts of this island, marrine terraces make distinctive development.Between the Kaneda Cape and the Sukoton Cape, some of the marine terraces are somewhat inclined. The geological construction of this island has a close connection with the development of the marrine terraces.Among the terraces, the lowest one has the widest distribution and is well preserved. This consists predominantly of rounded gravels of slate, with the thickness 3m to 0.5m.The upper surfaces of the bed rocks at the lowest terrace, vary from 20m to 9m, in height.