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Nishiyama Formation Omura, 1927

• Type locality (Old): Wada, Nishiyama town, Kashiwazaki city, Niigata prefecture
• Type locality (New): Jorakuji, Izumozaki city, Santo county, Niigata prefecture
• Coherent formation
• early Pliocene - early Pleistocene (4.7 - 2.3 Ma, FT)
• Contemporaneous heterotopic facies: Hachikokusan Formation
• Contemporaneous heterotopic facies (partly): Uonuma Formation
• Correlation: Taira Formation, Suyoshi Formation, Takegahana Formation, Tamugigawa Formation, Higashigawa Formation, Asojima Formation, Kurohime Formation, Nishiyama Formation
• Correlation (Upper): Tanihama Formation, Minagawa Formation, Hachioji Formation, Seguchi Formation
• Correlation (Middle): Nadachi Formation, Yoneyama Formation, Suganuma Formation
• Correlation (Lower): upper Kawazume Formation, Kakuma Formation, Hododaira Formation, Kawaguchi Formation, Nigoriike Formation

• Sedimentary facies: Marine
• Sedimentary facies: Continental slope
• Sedimentary facies (Hamatsuda facies): Outer fan of a submarine fan
• Sedimentary facies: Hemipelagic
• Water temperature: Warm ocean current and cold ocean current became dominant alternately.
• Depth of water: Upper bathyal
• Lithofacies: Mudstone
• Lithofacies (Hamatsuda facies): Mudstone-dominant interbedded sandstone and mudstone

• Thickness: ca. 350 - 650 m
• Upper limit: Boundary between the massive mudstone and the overlying sandy mudstone
• Upper limit: Conformity and unconformity (Haizume Formation)
• Lower limit: Boundary between the sandstone-dominant interbedded sandstone/mudstone and the overlying massive mudstone
• Lower limit: Transitional (Shiiya Formation)

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

• Distribution: Wada - Otsu - Nagamine - Hamatsuda, Nishiyama town, Kashiwazaki city, Niigata pref.; Shiiya, Kashiwazaki city, Niigata pref.; Yamada - Chuei tunnel - Ochimizu river - Shido bridge - Gomoto river - Natsuto - Tozaki, Teradomari, Nagaoka city, Niigata pref.; Kutsuta - Inohana - Jorakuji - Aida - Tanaka, Izumozaki city, Santo county, Niigata pref.; Magiyama - Kugami, Tsubame city, Niigata pref.; Saigenji, Kariwa city, Kariwa county, Niigata pref.
• Fossils: Diatoms, Sponges (Makiyama Chitanii)
• Fossils (Bivalves): Palliolum peckhami
• Fossils (Foraminifera): Angulogerina sp., Bathysiphon sp., Bolivinita quadrilatera, Bulimina nipponica, Cassidulina norcrossi, Cassidulina yabei, Chilostomella cf. oolina, Cibicides pseudoungerianus, Cibicides cf. refulgens, Cibicides ungerianus, Cribroelphidium yabei, Cribrostomoides cf. evoluta, Cribrostomoides cf. subglobosum, Cyclammina japonica, Cyclammina pusilla, Dentalina setanaensis, Epistominella pulchella, Globigerina bulloides, Globigerina incompta, Globigerina pachyderma, Globigerina quinqueloba, Globigerinoides ruber, Globobulimina auriculata, Globocassidullina subglobosa, Globoquadrina asanoi, Globoquadrina kagaensis, Globorotalia inflata, Globorotalia inflata praeinflata, Goesella schencki, Hanzawaia nipponica, Islandiella japonica, Martinottiella communis, Melonis nikobarensis, Melonis pompilioides, Miliammina echigoensis, Neogloboquadrina himiensis, Neogloboquadrina pachyderma, Oridorsalis umbonatus, Praeglobobulimina aurikulata, Pullenia apertula, Quinqueloculina vulgaris, Reophax sp., Saccammina sp., Trifarina kokozuraensis, Trochammina sp., Uvigerina akitaensis, Uvigerina nitidula, Valvulineria sadonica
• Fossils (Radiolarians): Spireuma? circularis, Spongodiscus spp., Stylatractus yatsuoensis, Thecosphaera japonica, Thecosphaera tochigiensis
• Fossils (Calcareous nannofossils): Braarudosphaera bigelowi, Calcidiscus leptoporus, Coccolithus pelagicus, Coccolithus streckeri, Crenalithus doronicoides, Dictyococcites sp., Discolithna cf. japonica, Gephyrocapsa aperta, Gephyrocapsa caribbeanica, Gephyrocapsa oceanica, Gephyrocapsa sinuosa, Helicosphaera carteri, Helicosphaera sellii, Pseudoemiliania lacunosa
• Fossils (Pollen): Alnus sp., Fagus sp., Pterocarya sp., Quercus sp., Taxodiaceae, Zelkova sp.
• Tephra: Ya, Znp, Ywg, Sdp, Ykp, Gos, Hap, Jwg, Tsp, Ngm, Fup, Chw, Sig, Srt-SK100, Jp, Jsg, Tzw, Arg, Ocg, Ths, Om-SK110

• Tanabe (2015) Jour. Geol. Soc. Japan, vol.121, no.9, pp.311-323, DOI
• Takano (2011) Jour. Geol. Soc. Japan, vol.117, no.4, pp.238-258 DOI
• Kobayashi et al. (2010) Jour. Geol. Soc. Japan, vol.116, no.11, pp.XVII-XVIII
• Kobayashi et al. (2002) Geology of the Sanjo District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 98p. (in Japanese with English abstract 4p.)
• Kobayashi et al. (1995) Geology of the Kashiwazaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 102p. (in Japanese with English abstract 4p.)
• Kobayashi et al. (1993) Geology of the Izumozaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 91p. (in Japanese with English abstract 4p.)