Holocene geomorphic development of coastal barriers in Japan

概要

論文の詳細を見る
Coastal ridges are widely distributed among the lowlands of the Japanese Islands. They represent former coastal barriers and beach ridges. In this paper, the geomorphic development of coastal barriers during the Holocene period is clarified from a study of six coastal lowlands and one coastal lagoon. The areas studied represent typical landforms of the Japanese coastal lowlands with ridges. Fossil foraminiferal assemblages were analysed to reconstruct the palaeoenvironmen-tal changes in the bays, which were formed by the Holocene transgression. The coastal barriers in the study areas had been commonly formed from the rise in sea level during the early to mid Holocene. The bays changed into lagoons by the emergence of barri-ers, formed as a result of decreasing rate in the rise of sea level. Furthermore, when the sea level lowered, the lagoons changed into marshes from the development of beach ridges seaward of the barriers. Differences in the development of the coastal barriers could be recognized from the period of enclosure by the barriers. The controlling factors of both the barriers' develop-ment and the landforms of the coastal lowlands are tectonic movements, the basal topog-raphy of coastal lowlands, and sediment supply.
慶應義塾大学日吉紀要刊行委員会の論文