松前半島南部の中新世前 : 中期における気温変化  [in Japanese] Climatic change during early and middle Miogene in the southern part of the Matsumae Peninsula, Hokkaido  [in Japanese]

The lower half of the Neogene strata in Southwest Hokkaido is composed mainly of pyroclastic and volcanic rocks, which are poor in fossils. However, in the southern part of the Matsumae Peninsula, the Yoshioka and Kunnui Formations (early to middle Miocene) contain non-pyroclastic argillaceous sediments at many horizons, which contain fossil pollens. The records of fossil pollens indicate the following climatic change during the early and middle Miocene in Southwest Hokkaido. Fukuyama Formation (early Miocene): cool temperate; Yoshioka Formation (early Miocene): early stage - warm and warm temperate; Yoshioka Formation (early Miocene): middle and late stage - cool temperate, Kunnui Formation (early to middle Miocene): warm temperate - temperate.