The Vegetational History during the Last Glacial Period from Yanohara Bog, Fukushima Prefecture, Northeastern Part of Japan

This paper describes the palynological study of a core from Yanohara Bog, Fukushima Prefecture, northeastern Japan. Four marker tephras laid down during the Last Glacial Period are recognized in the core: Pm-1, Aso-4, DKP, and AT.The pollen diagram obtained is divided into five pollen zones. The ages of the boundaries between the pollen zones are calculated from the depositional rate of the marker tephra. YH-I (about 8-5.7m.y.B.P.) corresponds to the early Last Glacial Age. Both YH-IIa (about 5.7-5.0m.y.B.P.) and YH-IV(2.6-1.4m.y.B.P.) correspond to cold stages. YH-V corresponds the Holocene.It is clear that there were two cold stages and one relatively warm stage during the Last Glacial Period. From pollen analytical data, it is found that the earlier cold stage(YH-IIa) was colder to than the later stage(YH-IV).