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Genbi Formation Hayakawa et al., 1954

• Type locality: Genbi valley, Genbi town, Ichinoseki city, Iwate prefecture
• Volcanic rocks
• late Miocene (5.7 Ma)

• Lithofacies: Dacite welded tuff

• Thickness: 40 - 150 m
• Upper limit: Unconformity (Tatsunokuchi Formation)
• Lower limit: Conformity (Onomatsuzawa Formation), Unconformity (Tsukumo Sandstone Member)

------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown

• Distribution: Genbi valley, Genbi town, Ichinoseki city, Iwate pref.; Iwagasaki, Kurikoma, Kurikoma city, Miyagi pref.

• Tsuchiya et al. (1997) Geology of the Iwagasaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 96p. (in Japanese with English abstract 4p.)