Western border of the Shizukuishi Basin, a part of Ou-Back-born Range, are composed of Neogene strata overlying on the Granitic Rocks. Stratigraphical sequence of Neogene strata in this area is as follows in descening order:
Both of the Hashiba Formation and the Yumoto Formation are considered to be nearly contemporaneous. Similarly the relation of the Yamatsuda Formation and Koshitomae Formation, and Osuke Formation are contemporaneous.