Molluskan assemblages from the sediment cores of the latest Pleistocene to Holocene incised-valley fills in Kakinoki, Soka City, Saitama Prefecture and Komatsugawa, Edogawa-ku, Tokyo Metropolis,central Japan.

Abstract

The latest Pleistocene to Holocene incised-valley fills distribute in the Tokyo and Nakagawa lowlands, Kanto Plain, central Japan. The deposits contain abundant molluskan fossils. We examined mollusks obtained from two sediment cores (GS-KM-1A and GS-SK-1) in the Tokyo and Nakagawa lowlands and recognized 6 species of gastropod, 15 species of bivalve, and 3 species of scaphopod from GS-KM-1A, and 6 species of gastropod, 15 species of bivalve, and 1 species of scaphopod from GS-SK-1. Based on the molluskan assemblage analysis, these sediment cores show environmental changes caused by a Holocene transgression-regression cycle, which comprises brackish intertidal/subtidal zone, marine subtidal zone, marine subtidal zone (inner-bay), marine-brackish subtidal zone,in ascending order.