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Ry Tephra Niigata Volcanic Ash Group, 1983

Abbr.: Ry

• Type locality: Tagawa river, Tokamachi city, Niigata prefecture
• Tephra
• Pleistocene

• Lithofacies: Rhyolite gravel-bearing volcanic ash, Volcanic sands, Pumice

• Host: Uonuma Formation
• Thickness: ca. 8 m

• Distribution: Tagawa river - Shimooita river - Sarashi river, 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.)