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Yachiho Formation

• Coherent formation
• Pleistocene

• Lithofacies: Mudflow deposit (2 flow units)
• Lithofacies (along Chikuma river): Mud, Sands, Pumice, Scoria
• Sedimentary structures (Mud, Sands): Cross stratification

• Thickness (Mudflow deposit, A unit): 2 - 5 m
• Thickness (Pumice): 50 cm
• Thickness (Scoria): 10 cm
• Lower limit: Unconformity (Usonokuchi Formation)

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

• Distribution: Toyosato farm - Mizonohara - Shukudo - Fudeiwa, Komi city, Minamisaku county, Nagano pref.; Saguchi - Nakahata - Shimohata, Sakuho city, Minamisaku county, Nagano pref.

• Kawachi (1974) Geology of the Tateshinayama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 114p. (in Japanese with English abstract 5p.)