The major part of the buried terraces in the lower Tama river plain has been correlated to the subaerial Tachikawa terrace, corresponding to the Last Glacial Maximum (Marine Oxygen Isotope Stage 2: MIS 2). Controversially, the recent study on buried terraces in the lower Sagami plain revealed that a broader portion of buried terraces were formed during the MIS 3. This study reexamines the chronology of both the subaerial and buried Tachikawa terraces in the middle and lower Tama river basin in relation with the sea-level history. Based on the tephrostratigraphy of terrace deposits, the main part of the subaerial Tachikawa terrace is to be divided into Tc1 and Tc2 surfaces, corresponding to MIS 3 and MIS 2. respectively. This reexamined subaerial Tc1 terrace surface continues to the main part of the buried Tachikawa terrace. Buried Tc2 terraces are recognized along the buried valley to a small extent. This indicates that the broader plain was formed during MIS 3, along the Paleo-Tokyo river which includes the Tama river basin. The classic term 'Tachikawa terrace' includes terraces formed both during MIS 2 and MIS 3, while the major part was formed during MIS 3.
Geographical Reports of Tokyo Metropolitan University 37 15-24, 2002
Department of Geography, Tokyo Metropolitan University