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Hagiu Formation (Yaguchi, 1989) Gunma Geological Map Compilation Committee, 1999

Invalid synonym: Oshinara Formation, Oto Formation, Aihara Formation, Wakasari Formation

• Type locality: Kurabuchi hot spring, Gonda, Kurabuchi town, Takasaki city, Gunma prefecture
• Coherent formation
• Lake-fill deposit located between Kanpo volcano and Haruna volcano
• Pleistocene (0.5 - 0.4 Ma)

• Sedimentary facies: Lacustrine
• Lithofacies: Tuffaceous silt
• Lithofacies (Minor): Tuffaceous sands, Gravels, Peat, Pyroclastic rocks
• Sedimentary structures: Parallel stratificaiton

• Thickness: 20 m or thinner
• Distribution (East-West): ca. 4 km
• Distribution (South- North): ca. 4 km
• Upper limit: Interfingered (Older Haruna Volcanic Fan Deposits)
• Lower limit: Unconformity (Kanpo Volcanic Rocks)

• Distribution: Kurabuchi hot spring, Gonda, Kurabuchi town, Takasaki city, Gunma pref.; Kenjo river - Hagius, Higashiagatsuma city, Agatsuma county, Gunma pref.
• Tephra: Crystal ash

• 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.)