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Aimagawa Formation Akima Collaborative Research Group, 1975

• Type locality: Aima river, Kawasugawa river, Kurabuchi town, Takasaki city, Gunma prefecture
• Volcanic rocks
• Multiple stratovolcanoes
• Pliocene - early Pleistocene (4.45 - 1.79 Ma, K-Ar; 2.2 Ma, FT)
• Contemporaneous heterotopic facies: Akima Formation
• Intruded by: Andesite

• Sedimentary facies: Terrestrial
• Lithofacies: Tholeiite, Calc-alkaline
• Lithofacies: Pyroxene andesite lava, Volcanic breccia, Pyroclastic flow deposit
• Sedimentary structures (Pyroclastic flow deposit): Reversed graded bedding

• Source: Mount Tsunoochi, Mount Kennomine
• Thickness: 500 m or thicker
• Thickness (Lava): 20 - 40 m
• Upper limit: Unconformity (Older Haruna Volcanic Fan Deposit, Kanpo Volcanic Rocks, Jizotoge Formation)
• Lower limit: Angular unconformity (Itahana Formation)

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

• Distribution: Aima river, Kawasugawa river, Kurabuchi town, Takasaki city, Gunma pref.; Mount Takatoya, Matsuida town, Annaka city, Gunma pref.; Masuda river, Kamimasuda, Annaka city, Gunma pref.

• Geshi and Takeuchi (2012) Geology of the Haruna San District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 79p. (in Japanese with English abstract 3p.)