The tephra and peat beds distributed at Tokotan and Honbekkai in the eastern margin of the Konsen Plateau, Eastern Hokkaido, were investigated by tephra stratigraphy, pollen analysis, and
14C datings. The peat layers of Tokotan Loc. 1 were estimated to date from the late stage of the Last Glacial Age. Four pollen zones were discriminated there. The lowest zone, TK-I, about 36, 000y. B. P., is characterized by high pollen percentages of
Picea coexisting with
Larix and
Abies. Zone TK-II is characterized by high
Larix, Betula, Alnus, and herbs. Zone TK-III, a little older than 32, 000y. B. P. in age, is dominated by
Picea. The uppermost zone, TK-IV, is estimated at about 32, 000y. B. P. based on the existence of Nl-a and Spfa-l, and it has high percentages of
Larix, Picea and herbs. During the formation of these 4 zones, there could be subarctic forests (zones TK-I and TK-III) and subarctic open forests (zones TK-II and TK-IV) dominated by larch and/or spruce on bogs. Generally, the climatic conditions of zones TK-I-IV was colder and drier than at present, especially in zone TK-II, and less so in zone TK-III.
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