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Ooka Mudflow Deposit Kato and Akahane, 1986

• Type locality: Yonedawa - Lake Kogemiike, Ooka, Nagano city, Nagano prefecture
• Coherent formation
• middle Pleistocene

• Sedimentary facies: Mudflow deposit
• Lithofacies: Gravels
• Lithofacies (Upper, Matrix): Mud
• Lithofacies (Lower, Matrix): Volcanic ash

• Thickness: 150 - 200 m
• Source: Hijiriyama Volcanics
• Upper limit: Unconformity (Omachi Tephra)
• Lower limit: Unconformity (Hijiriyama Volcanics, Joshita Member, Shinoyama Volcanics, Haibara Formation, Komiji Member, Nagaiwa Member, Kumeji Pyroclastic Member)

• Distribution: Yonedawa - Lake Kogemiike - Hijirigawa creek - Lake Ashinuma - Lake Ogemiike - Ogikubo - Amaike - Kurio - Takaichiba, Ooka, Nagano city, Nagano pref.

• Kato et al. (1989) Geology of the Omachi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 111p. (in Japanese with English abstract 7p.)
• Kato and Akahane (1986) Geology of the Nagano District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 120p. (in Japanese with English abstract 5p.)