Paleo-Tokyo Bay, the sedimentary basin of the Narita group, which is the repesentative marine Pleistocene deposits in Japan, originates as the Kanto sedimentary basin with the middle Miocene diastrophism of the Tanzawa orogenesis. From the facies analyses (both lithologic and paleontologic facies) of the upper part of the Kazusa group deposited in the Kanto sedimentary basin, it is concluded that the sedimentary environment of the strata gradually changed from bathyal one into neritic, toward the upper, and this change proceeded from the southwest toward the northeast in the basin. The environmental change from open sea to coastal water at the uppermost horizon of the Kazusa group occurred in the whole district, and at the same time a weak diastrophism suggested by the partial unconformity between Kazusa and Narita group, and thus the depositional area of the Narita group shifted to the north. This is the beginning of the movement of Kanto tectonic basin which has continued up to the present, and the movement resulted the paleogeographical change, and the Paleo-Tokyo Bay was formed.
The Ozegahara Basin is a typical sphagnum-moor, which is situated in Central Japan about 1400 meters above the sea level. Among plants growing in the moor are found many species which are inferred the relic of the last ice age. This basin was born in younger Pleistocene because of damming up the ancient valley of the River Tadami by the lavas from the Hiuchidake Volcano (2346m). At the northeastern corner of the moor are found the peat layers alternating detritus overlaid the deposits of mudflow from Hiuchidake. Stratigraphically these peat layers are correlated to uppermost Pleistocene. According to the pollen analytical data, pollen grains of conifer are predominant through the layers and reversely Fagus pollen grain is very few or partly not in the samples, while the present moor is surrounded by Fagus forest and pollen spectrum from the surface sample of the moor reflects this state. From these results it may be concluded that the temperature of this area at that time was 1-2°C lower than the present day.
The Araya site is located at Araya, Kawaguchi-machi, Kita-Uonumagun (County, ) Niigata Prefecture. The excavation was carried out by the auther from the 29th of April, 1958, to the 5th of May. Numerous stone artifacts manufactured from hard-shale were collected from the yellowish loamy sand layer below the surface soil. A total of 2187 artifacts include: 676 microblades; 2 blades; 1012 burin-spalls; 4 end-blades; 6 choppers; 2 perforators; 5 points; 401 gravers; 11 scrapers; 1 flake-core; 24 keel-shaped micro-cores; and 45 utilised flakes. The Araya industry may be attributed to the latest stage of the Pre-Pottery Age in Japan. It should be noted that 401 specialized gravers were found in association with 676 microblades at this site. The distribution of the Araya-type graver is limited to the northeastern part of Honshu and Hokkaido island.