札幌市北方低地帯における沖積世の古気候変遷

概要

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Holocene in the lowland area of north of Sapporo, Hokkaido, is divided into 3 pollen assemblage zones.The earliest Picea-Betula-Myrica Zone (Ca. 7.000 yrs. B. P.) carries dominant Picea and Abies. The climate indicated by this pollen assemblage is considered to have been cooler than the present one. In contrast with the terrestrial condition shown by the assemblage, however, warm water molluscs lived in the sea. The age of the above assemblage may be near the time of the maximum "Holocene transgression".The overlying Quercus-Juglans Zone is dominated by the temperate broadleaved forest, which shows the climate warmer than the present one, and corresponds to the Climatic Optimum.The latest Quercus-Abies Zone becomes slightly cooler than the preceding zone, with the vegetation quite similar to that of the present.The above mentioned climatic change correlates well with the result of our pollen analysis at Yubetsu on the Okhotsk coast where the climate in 7, 000 yrs. B. P. was cooler than the present condition.
日本第四紀学会の論文