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Yashirogawa Debris Avalanche Deposits Hayatsu, 1985

Invalid synonym: Myoko Volcanic Mudflow Deposit II

• Type locality: Nisso-daisan power plant, Yashiro river, Nihongi, Myoko city, Niigata prefecture
• Volcanic rocks
• late Pleistocene (20 ka; 20,200 - 17,900 yBP, ¹⁴C)

• Lithofacies: Volcanic mudflow deposit
• Lithofacies: Pyroxene andesite breccia, Volcanic ash, Mud, Sands

• Source: Myoko volcano
• Thickness: Several - a few 10 m
• Distribution: ca. 50 km²
• Volume: ca. 0.5 km³
• Upper limit: Unconformity (Otagirigawa Pyroclastic Flow Deposit, Alluvial fan deposit)
• Lower limit: Unconformity (Shibuegawa Pyroclastic Flow Deposit)

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

• Distribution: Yashiro river - Bannai river - Higashinagamori - Sagawa - Shidairoku - Higashishi - Sanbongishinden - Shibue river - Katakai river, Myoko city, Niigata pref.

• Yanagisawa et al. (2000) Geology of the Iiyama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 144p. (in Japanese with English abstract 6p.)
• Akahane and Kato (1989) Geology of the Takada-Seibu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 89p. (in Japanese with English abstract 3p.)