Marine clay deposits on the US (Holocene upper sand bed) in Arakawa Lowland, Saitama Prefecture

Abstract

The Arakawa Lowland is situated in the western part of the Kanto Plain. Diatom analyses of a large number of boring core samples obtained from the Lowland have been performed, and marine clay deposits on the US (Holocene upper sand bed) have been found in the Arakawa Lowland. The geomorphological history of this area in the Holocene period is inferred as 1) between about 7970 yr BP and 4860 to 3130 yr BP, fluvial valleys were drowned by Jomon transgression and were filled with marine sediments; 2) from about 5270 to 4570 yr BP the US (Holocene upper sand bed) was formed in this area; 3) around 3990 yr BP, marine clay deposits accumulated on the upper sand bed; 4) after the period 4450 to 3130 yr BP the uppermost alluvial deposits were formed. -from English summary