Late Holocene relative sea-level changes and reconstruction of paleoenvironment by diatom fossil assemblage analysis in Akkeshi Moor, Hokkaido, northern Japan

Paleoenvironmental surveys, using diatom assemblage analysis, have been carried out in Akkeshi Moor and its surroundings to obtain records of Holocene sea-level changes. Fossil diatom assemblages and radiocarbon ages of drilled core samples from three sites in the moor were examined, demonstrating relative sea-level fluctuations during the last five thousand years, with the following sequence of events: a shallow bay spread over most of Akkeshi Moor, with gregarious oysters around the moor (ca. 4700 yr B.P.); the sea-level dropped to about 1 meter below the present level (ca. 2700 yr B.P.); the sea-level then rose to about 1 meter above the present level (ca. 1000 yr B.P.). Moor vegetation formed after this transgression.