1) We have examined, by the method of pollen analysis, the Yasuda formation that is the deposits of the Shimosueyoshi stage, at Yokoyama, Yoso, Nozaki, Nishiyama and Yukinari in Kashiwazaki Plain in Niigata Prefecture.
As the results, Alnus, Quercus, Tilia, Fagus, Cryptomeria, Juglans and Pinus dominated in the Lower Yasuda formation. The central part of the Upper Yasuda formation has no great difference from the Lower Yasuda formation, though the central part of the Upper Yasuda formation might intermingle some more fossil pollen of Tsuga diversifolia type among collection Tsuga than the Lower Yasuda formation did.
At the top of the Upper Yasuda formation, Alnus and Tsuga dominated, there were more Abies and Picea contained than at any other place, and Tsuga consisted of the fossil pollen of Tsuga diversifolia type.
2) The Lower Yasuda formation was classified into two parts, upper half and Lower half, because it may be noticed slight difference in the assemblage of pollens, but its boundary is not clear.
3) It was recognized that the paleoclimate in the process of the deposition of the Yasuda fo rmation was getting cooler with the change from the Lower to the Upper; it was warm in the Lower, slightly cool in the central part of the Upper and cool in the top of the Upper.
4) The Yasuda formation deposited in the inland bay in the process from transgression (the Lower Yasuda formation) to regression (the Upper Yasuda formation).
5) Old Sand-dune of Arahama Sand-dune was made up in the process of regression in getting colder in the climate after the age of the deposition of the Yasuda formation.
6) The Lower Yasuda formation may be correlated to the Iwano formation that produced Palaeoloxodon naumanii at the Yoneyama coast.
7) The Yasuda formation may be correlated to the Hirayama formation and the Haranomachi formation in the Takada plain, the Iwano formation at the Yoneyama coast, and the Kuninaka formation in the Kuninaka plain (Sado Island).