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Shirahama Formation (Naruse et al., 1951) Kotake, 1988
- Type locality: Shiramazu, Chikura town - Otohama, Shirahama town, Minamiboso city, Chiba prefecture
- Coherent formation
- Trench fill sediments, Landward slope basin of trench
- late Pliocene (3.4 - 2.6 Ma, K-Ar)
- Correlation: Anno Formation
- Sedimentary facies: Marine
- Sedimentary facies: Turbidite, Debris flow deposit
- Lithofacies: Sandstone-dominant interbedded sandstone and mudstone
- Lithofacies (Minor): Conglomerate
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Chikura village - Shiramazu - Otohama - Cape Nojima - Kawashita, Minamiboso city, Chiba pref.; Mera fishing harbour, Tateyama city, Chiba pref.
- Fossils: Sharks (Teeth), Bivalves (Glycymeris yessoensis), Wood fragments, Foraminifera, Radiolarians, Diatoms, Calcareous nannofossils
- Tephra: SH
- Utagawa et al. (2017) Jour. Geol. Soc. Japan, vol.123, no.11, pp.969-976 DOI
- Okada et al. (2012) Jour. Geol. Soc. Japan, vol.118, no.2, pp.97-108 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.)