Late Quaternary Landform Development of the Kanto Plain

Abstract

The Kanto Plain is the tectonically active setting of the Tokyo metropolitan area. It is characterized by widespread uplands, consisting of Pleistocene fluvial, marine sediment, tephra layers, and narrow lowlands filled with thick Holocene alluvium. This landscape owes its origin to the interaction of basin-forming movements, eustasy, erosion, and sedimentation during the Quaternary Period. Marine transgressions in marine isotope stages (MIS) 11, 9, and 5.5 repeatedly overlapped the land, producing Paleo Tokyo Bay, with its wide mouth facing the Pacific Ocean to the east. In contrast, the Holocene (MIS 1) marine transgression was limited to the river valleys incised since MIS 4, and instead of Paleo Tokyo Bay, Modern Tokyo Bay has appeared. Modern Tokyo Bay, which opens to the south, resulted from the combination of: (1) a lower sea level in MIS 1 than in MIS 5.5; (2) tectonic uplift of the Kanto Plain, especially the east side; and (3) the accumulation of fluvial sediment and tephra since MIS 5.4.