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Negishi Formation (Koike et al., 1985) Kurihara et al., 2003

Invalid synonym: Negishi Sandstone Member (Iwadono Formation, Tokigawa Group), lower Shogunzawa Mudstone Member

• Type locality: Mae river, Negishi, Ranzan city, Saitama prefecture
• Coherent formation
• middle Miocene

• Sedimentary facies: Marine, Continental shelf margin, Very slow deposition rate
• Lithofacies: Massive medium to coarse-grained silty sandsotne, Glauconite-bearing, Calcareous
• Sedimentary structures: Cross-stratification

• Thickness: 15 - 30 m
• Upper limit: Conformity (Shogunzawa Formation)
• Upper limit: Top of the I-3 Tuff Bed (around 12.7 Ma)
• Lower limit: Conformity (Godo Formation)
• Lower limit: Lithofacies boundary (around 15.0 Ma)

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

• Distribution: Rokujizo, Ogose city, Saitama pref.; Hinohara - Negishi, Ranzan city, Saitama pref.; Sue, Hatoyama city, Saitama pref.; Godo - Kuzubukuro, Higashimatsuyama city, Saitama pref.
• Fossils: Bivalves, Gastropods, Scaphopods, Crustaceans, Echinoids, Brachiopods, Sharks (Vertebra), Plants (Leaves), Solitary corals, Solitary corals, Siliceous sponges, Forams, Ostracods, Calcareous nannofossils, Rosselia isp.
• Tephra: I-O, I-1, (I-2), I-3

• Takahashi and Yanagisawa (2004) Jour. Geol. Soc. Japan, vol.122, no.12, pp.625-635.
• Kurihara et al. (2003) Jour. Geol. Soc. Japan, vol.109, no.4, pp.215-233.
• Koike et al. (1985) Jour. Geol. Soc. Japan, vol.91, no.10, pp.665-677.