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Hiruzenbara Formation

• Coherent formation
• Pleistocene
• Contemporaneous heterotopic facies: Somma

• Sedimentary facies: Lacustrine
• Lithofacies (Upper): Tuff breccia
• Lithofacies (Middle): Mudstone, Sandstone, Conglimerate, Volcanic ash
• Lithofacies (Middle, Minor): Lignite
• Lithofacies (Lower): Clay, Diatomite
• Lithofacies (Lower, Minor): Tuff, Volcanic conglomerate

• Thickness (Upper): ca. 80 m
• Thickness (Middle): 30 - 40 m
• Thickness (Lower): 100 m or thicker

• Distribution: Asahigawa river - Kawakami - Omori - Hanazono, Maniwa city, Okayama pref.
• Fossils: Fishes, Shellfishes
• Fossils (Plants): Carpinus sp., Cryptomeria sp., Fagus palaeocrenata, Quercus cfr. palaeocrispula
• Fossils (Diatoms): Cyclotella comta, Melosira granulata, Stephanodiscus niagarae, Stephanodiscus ostraea var. minutula

• Ota (1962) Yumoto, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 29p. (in Japanese with English abstract 3p.)
• Ota (1962) Akasaki & Daisen, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 37p. (in Japanese with English abstract 3p.)