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Nishi Formation

• Coherent formation
• middle Pleistocene

• Lithofacies (Upper): Sands, Silt
• Lithofacies: Gravels
• Lithofacies (Minor): Pumiceous silt, Peat

• Thickness: 100 m or thicker
• Upper limit: Unconformity (Uenohara Formation, Nosegahara Formation)
• Lower limit: Unconformity (Uonuma Formation)

• Distribution: Omoigawa - Koguriyama - Hitomurao, Minamiuonuma city, Niigata pref.
• Fossils (Plants): Juglans sieboldiana var. sachalinensis

• 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.)