北部フォッサ・マグナ地域の軟体動物群の時代的変遷について

概要

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1. Judging from the historical change of the Molluscan Fauna, in the lowest Moriya Formation the mixed Fauna of both Oligocene and Miocene is seen，but in the each Formation of Uchimura, B essho, Aoki and Ogawa only the complete Miocene type remains and sometimes the old type is observedas relic. In the Shigarami Formation the special Fauna is made of the mixture of both Miocene and Pliocene type. 2. Judging from the Molluscan Fauna， in the early Miocene the sea of the Northern Fossa Magna had the elements of the bay and was shallow, but in the Middle Miocene it became the open sea， and the depth of it increased. From the end of the Middle Miocene it showed a tendency to rise， especially in the Central Uplift Zone the rising quantity was very large. And in the upper Miocene it was separated into east and west side. The west side sea was divided into several sedimentary basins，b ecame the sea of shallow Shigarami and showed gradually a tendency to change into the land.
信州大学教養部の論文
1973-03-15