Japanese wave-dominated coasts as palaeoenvironmental records

Abstract

The majority of Japanese depositional coasts are dominated by wave and wave-induced sedimentary processes. Long-term sedimentation in the wave-dominated coasts associated with sandy and gravelly beaches results in development of beach ridges and coastal dunes. While beach ridges and dunes are expected as valuable sedimentary archives of palaeoenvironment, they have not attracted much attention in Japanese coasts for decades. Recent development of the ground-penetrating radar (GPR) and optically-stimulated luminescence (OSL) dating enabled the continuous survey of subsurface structures and quantitative dating of sandy and gravelly deposits ; and if these techniques are applied, Japanese coasts can be a tremendous repository of palaeoenvironmental records. This paper reviews geographic features of beach ridges and dunes in Japanese coasts, and their possibilities as records of past shorelines, sea level, winter monsoon, and coastal hazards.