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Tokaishoku volcanic ash Niigata Volcanic Ash Group, 1983

• Type locality: Iriyama creek, Kawanishi, Tokamachi city, Niigata prefecture
• Tephra
• Pleistocene

• Lithofacies: Vitreous volcanic ash

• Host: Uonuma Formation
• Thickness: 60 - 80 cm

• Distribution: Iriyama creek, Kawanishi, Tokamachi city, Niigata pref.

• 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.)