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Higashinagata Formation Nakao et al., 1986

• Type locality: Idenoo, Tateyama city, Chiba prefecture
• Coherent formation
• Landward slope basin of trench
• middle Pleistocene (0.78 - ? Ma)
• Correlation: Hongo Formation, Kokumoto Formation, Ichijiku Formation, Chonan Formation, Kasamori Formation

• Sedimentary facies: Marine
• Lithofacies: Siltstone-dominant interbedded sandstone and tuffaceous siltstone
• Sedimentary structures: Slump structures

• Thickness: 400 - 500 m
• Upper limit: Interfingered (Takigawa Formation)
• Lower limit: Unconformity (Kamo Formation)

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

• Distribution: Idenoo - Nishinagata - Sano - Komoguchi - Ina - Nanjo, Tateyama city, Chiba pref.
• Fossils: Shellfishes, Radiolarians, Diatoms, Calcareous nannofossils
• Fossils (Foraminifera): Gephyrocapsa caribbeanica, Gephyrocapsa oceanica, Gephyrocapsa parallela, Groborotalia truncatulinoides, Pulleniatina obliquiloqulata
• Tephra: IH, CR, BZ

• Utagawa et al. (2017) Jour. Geol. Soc. Japan, vol.123, no.11, pp.969-976 DOI
• Kawakami and Shishikura (2006) Geology of the Tateyama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 82p. (in Japanese with English abstract 5p.)
• Suzuki et al. (1990) Geology of the Nago District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 48p. (in Japanese with English abstract 3p.)