The Kushiro group developed extensively around the Kushiro plain in eastern Hokkaido, is one of the typical lower Pleistocene complexes. Result of pollen analysis of the three formations of this group is shown in the following table. Considering the climatic change during its accumulation judged from the forest association and the sea water thermal condition inferred from the fossil molluscus and foraminifera, we may be able to assume that three cold and two warm periods are shown in this group. From its stratigraphical relation to the underlying deposits, faunal aspect, relation to the marine terraces and above cited climatic condition, the Kushiro group may belong to the lower Pleistocene series, ranging in age from the Günz glacial stage to at least the Mindel-Riss interglacial stage.
The Kobui Terrace in the vicinity of the Esan Volcano, southeastern part of the Oshima Peninsula, Hokkaido, is formed of the Kobui Formation consisting of sand and volcanic ash. This is underlain with unconformity by the Tertiary sediments and superposed with unconformity by the Menagawa Volcanic Ash. The Kobui Formation contains the drift woods of Picea, Abies and Larix and the associated pollen flora. The terrace can be traced from the foot of the Esan Volcano westwards to near Hakodate City, where three terraced plains are developed. The Kobui Terrace continues to the middle terrace among them. The Kobui Formation can be dated as the Last Interglacial Stage. On the southern foot of the Esan Volcano, the Kobui Formation comprises beds of ejecta originated from the somma of the volcano and the lava of the central cone overlies the Kobui Terrace. This lava partly flowed into the valleys dissected on the terrace plain. The central cone of the Esan Volcano may be dated as the Last Glacial Stage or as Recent.
In part I of this paper the writer mentioned the recent progress and the present situation of American and European studies on the various problems of Pleistocene climatic changes. In addition, the writer discussed some relating problems in Japan. The ultimate purpose of this paper is to correlate the Pleistocene climatic changes in the Japanese Islands with these changes in North America and Europe, and to establish the chronological time table of the East Asiatic continent. In part II, the writer shall discuss about his glacial-geologic study in the high mountains of Japan, together with the eustatic oscillations of sea level along the coast of the Japanese Islands. The writer is now engaged in the paleolimnological study of Lake Biwa-ko which appeared in Tertiary and has kept lake water throughout the Pleistocene up to the present day. Accordingly, the sediments of Lake Biwa-ko must indicate the whole Pleistocene ecology of the Japanese Islands. The study of the sediments of this lake is, therefore, exceedingly important in order to establish the whole history of the Pleistocene climate of Japan. The study on this ancient lake will be published later on. The writer hopes to discuss the details of his whole study in American or European periodicals in near future.
Imizu plain is situatud in the north of Central Japan. Subsurface geology in this plain has been only partly known although there occurrs natural gas. The result of detailed examination of the well data in this plain is as fodlows. Alluvial deposits: peat alternation of sand and clay conglomerate total thickness: 0∼85m Dilluvial deposits: sand and mud alternation intercalating some conglomerate conglomerate total thickness: 20∼100 The deposits in this plain are not marine fine deposits as Kanto basin but non-marine sand and conglomerate, and become thicker towards the Hojyozu Lagoon.
The Nakanosawa Site is situated in the midst of an eastern highland so-called Nobeyama Plateau in the Yatsugatake Mountains. In November 1954, Chosuke Serizawa, Masakazu Yoshizaki and Shigeya Yui excavated this site and corrected many fragments of the potteries, stone-impllements and clay earrings. These remains were dug out from single layer which is black soil accumulated on a volcanic ash layer. Therefore from the point of the archeological view, all those relics are regarded to have existed at the same Period. My typo ogica research has been concentrated on the potteries and clay earrings only. The potteries are divided into two groups-patterned and non-patterned ones. The former are redivided into two sorts; “cord-marked” and “patterned with incised-lines or clay nicked-strings.” The “cord-marked” pottery has a close connection with that found in Tohoku and Kwanto districts in Japan. And the others are those which were native in south-eastern parts of Nagano Prefecture extending to Yamanashi Prefecture; it seems that they may have something common to the contemporary types in Tokai District. Chronologically, the Nakanosawa site comes under the category of the beginning of the lateast Jomon Period (Jomon Period is divided into five), about 1, 000 B. C.