Bulletin of the Mizunami Fossil Museum

Bulletin of the Mizunami Fossil Museum No. 1

The stratigraphy of the Miocene Mizunami group has been studied and synthesized. Four divisions are recognized: the Toki lignite bearing, Hiramaki, Akeyo and Oidawara formations in ascending order. The fomer two formations were made under a fresh water environment and the latter two are made of marine sediments. The Akeyo formation consists of 4 members and five facies. The Oidawara has two members. Two disconfomities divide the group into three units–– the Toki lignite bearing the Hongo and the Akeyo, and the Oidawara.

Each formation and member is described in details and the geological structure is discussed. Structure contour map of the base surface of each formation and many geologic columnar sections are shown in the figures.