Seven pollen zones have been newly established in the subsurface Late Quaternary formations developed in the coastal plain of the Ishikari Bay. Nearly continuous cores, with a total length of 130 to 200m were obtained at four drilling sites; they were used for the present study.
Past climate in this region may have been generally colder than the present climate in the Latest Pleistocene, although frequent fluctuations have been brought to notice.
The oldest of these pollen zones I would indicate the coldest climatic conditions throughout the entire horizons investigated due to the presence of Spruce-Larch-Fir vegetation, while Zone IV (older than 26, 000y.B.P. but younger than 29, 000y.B.P.), seems to have been generated under slightly warmer conditions than the older Zones I, II and III. Zone II is represented by Spruce-Hemlock-Fir vegetation, and Zone III (around 30, 000y.B.P.) is characterized by Spruce-Fir vegetation. Zone IV contains a Fir-Spruce-Elm vegetation. Zone V seems to have been generated almost under the same climatic conditions as Zone III. Zone VI, represented by Spruce-Fir-Larch-Birch vegetation, might have been formed under rather colder conditions as compared with Zone V. Zone VII may represent a part of the Holocene time, eventually not much warmer than the present climate.