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Furuto Formation (Collaborative Research Group on the Geology of the Shitada Hills, 1976) Kudo et al., 2011

Invalid synonym: Wanazu Formation, Hiu Formation, Kariwa Formation, Yashiroda Formation, Tsukayama Formation

• Type locality: Otogairi creek, Furuto, Sanjo city, Niigata prefecture
• Coherent formation
• Pliocene - Pleistocene (ca. 1.45 - 1 Ma)

• Sedimentary facies: Marine
• Sedimentary facies: Inner continental shelf, Shoreface
• Lithofacies: Sands
• Lithofacies (Minor): Gravels, Mud
• Sedimentary structures: Bioturbation, Parallel stratification, Trough cross-stratification, Planar cross-stratification, Hummocky cross-stratification, Swaley cross-stratification, Gravel dunes

• Thickness: ca. 30 - 200 m
• Upper limit: Unconformity (Uonuma Formation, Komagome Formation, Hirote Formation, Higher I Terrace Deposit, Higher II Terrace Deposit)
• Lower limit: Interfingered (Minagawa Formation), Transitional (Iwanosawa Formation), Unconformity (Nishitajiri Formation)

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

• Distribution: Otogairi creek, Furuto, Sanjo city, Niigata pref.; Shitada, Sanjo city, Niigata pref.; Chofukuji, Kamo city, Niigata pref.; Uonuma city, Niigata pref.
• Distribution (Wanazu Formation): Wanazu, Kawaguchi - Uono river - Yamakoshi, Nagaoka city, Niigata pref.
• Fossils: Shellfishes, Burrows
• Fossils (Wanazu Formation): Steller sea lion (Eumetopias ojiyaensis), Whales (Ribs)
• Fossils (Wanazu Formation, Shellfishes): Acila insignis, Anadara amicula, Anodontia stearnsiana, Antiplanes contraria, Callithaca adamsi, Clinocardium sp., Cryptonatica janthostomoides, Cryptonatica russa, Dosinia japonicum, Felaniella usta, Glycymeris yessoensis, Lucinoma actilineata, Lucinoma annulata, Macoma tokyoensis, Mercenaria stimpsoni, Mercenaria yokoyamai, Mizuhopecten sp., Myadora japonica, Mya japonica, Ophiodermella ogurana, Peronidia zyonoensis, Protothaca jedoensis, Pseudocardium sachalinensis, Saxidomus purpuratus, Siliqua alta, Solen striclus, Turritella saishuensis motidukii, Umbonium akitanum
• Fossils (Wanazu Formation, Foraminifera): Ammonia beccarii, Anomalina glabrata, Brizalina robusta, Cassidulina sublimbata, Cassidulina yabei, Cibicides cf. aknerianus, Cibicides lobatulus, Cibicides pseudoungerianus, Cibicides cf. refulgens, Elphidium crispum, Elphidium etigoense, Epistominella pulchella, Globigerina buloides, Globigerina pachyderma, Globigerina rubescens, Globocassidulina subglobosa, Globocassidulina subglobosa depressa, Guttulina sadoensis, Islandiella japonica, Lagena apiopleura, Oolina costata, Oolina melo, Polymorphia charlottensis, Pullenia apertula, Pyrgo spp., Quinqueloculina elongata, Quinqueloculina sawanensis, Quinqueloculina seminula, Quinqueloculina subarenaria, Sigmomorphina ozawai, Sigmomorphina semitecta, Trifarina hughesi, Uvigerina proboscidea, Valvulineria sadonica
• Tephra: Srt-SK100, Om-SK110
• Tephra (Wanazu Formation): Wz, Ko

• Kudo et al. (2011) Geology of the Kamo District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 162p. (in Japanese with English abstract 4p.)
• Takahashi et al. (2004) Geology of the Suhara District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 80p. (in Japanese with English abstract 4p.)
• Kobayashi et al. (1991) Geology of the Nagaoka District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 132p. (in Japanese with English abstract 6p.)
• Yanagisawa et al. (1986) Geology of the Ojiya District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 177p. (in Japanese with English abstract 6p.)
• Yanagisawa et al. (1985) Geology of the Tokamachi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 104p. (in Japanese with English abstract 6p.)