Abstract
The article is summarized as follows:
(1) It has been a current view that in the eastern part of the Tama Hills extend two terrace surfaces, that is, older Tama II and younger Shimosueyoshi terraces. But the authors found another terrace called Tsuchihashi terrace which intervenes between Tama II and Shimosueyoshi terraces in age is distributed in the middle of the slopes bordering the two terraces. It is probable that a regression occurred between Tsuchihashi and Shimosueyoshi stages, but it is not yet answered whether a regression intervened between Tama II and Tsuchihashi stages.
(2) The authors found consolidated dark blue part of the volcanic ash exclusively in the lower horizon of Musashino “loam” overlying these terraces in this area. The authors believe that the part is unweathered volcanic ash rapidly fallen in remarkable thickness. But it is also possible that the color of the part was resulted from reduction by underground water.
