Relative sea-level rise in the middle to late Yayoi Era observed in the Otagawa lowland, Pacific coast of central Japan

Abstract

This paper discusses the relative sea-level rise around 100BC to 300AD for the Otagawa lowland, on the western Shizuoka coast, central Japan. Sea-level rise in this area was estimated from the occurrence of “marine mud” at the excavation sites for river improvement. The marine mud (up to 25cm thick) lying on the freshwater peat yields fossils of molluscs and diatoms, suggesting deposition at the intertidal zone. It is covered by muddy riverine and marsh deposits. The timing of the sea-level rise was determined based on a total of twelve ¹⁴C ages and the archaeological age of potsherds. Relative sea-level rise during the period concerned may be attributed to local tectonic subsidence on the millennial time scale in the study area.