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Yamagami Formation Masatani and Tamura, 1959

Invalid synonym: Sugaya Formation

• Type locality: Uda river, Yamakami, Soma city, Fukushima prefecture
• Coherent formation
• Middle Jurassic, Callovian

• Sedimentary facies: Shallow marine
• Lithofacies: Sandstone
• Lithofacies (Minor): Shale
• Sedimentary structures: Bioturbation
• Sedimentary structures (Upper): Cross-stratification

• Thickness: ca. 250 m
• Upper limit: Conformity (Tochikubo Formation)
• Lower limit: Bottom of calcareous limestone with bioturbation
• Lower limit: Confromity (Awazu Formation)

• Distribution: Yamakami - Awazu - Zenigamidaira, Soma city, Fukushima pref.
• Fossils (Bivalves): Fimbria somensis, Isotrigonia masatanii, Isognomon sp., Latitrigonia unicarinata, Liostrea sp., Lopha sp., Mesolinga masatanii, Myophorella sugayensis, Nipponitrigonia sagawai, Plagiostoma aff.subcardiiforme, Pronoella sugayensis, Scaphotrigonia somensis

• Taketani and Osozawa (2013) Jour. Geol. Soc. Japan, vol.119, Supplement, pp.68-81 DOI
• Yanagisawa et al. (1996) Geology of the Somanakamura District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 114p. (in Japanese with English abstract 9p.)
• Fujita et al. (1988) Geology of the Kakuda District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 99p. (in Japanese with English abstract 9p.)