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Nakaumi Formation Mii, 1962

Invalid synonym: Nakanoumi Formation

• Type locality: Lake Nakaumi, Shimane prefecture - Tottori prefecture
• Coherent formation
• Holocene (10 - 3 yBP, ¹⁴C)
• Correlation: Yumigahama Sandbar

• Sedimentary facies (Upper): Marine, Brackish
• Sedimentary facies (Middle): Marine
• Sedimentary facies (Lower): Marine, Brackish
• Sedimentary facies: Lagoon
• Sedimentary facies (Minor): Alluvial fan near the river mouth, Delta
• Lithofacies (Upper): Clay, Silt
• Lithofacies (Upper, Minor): Sands, Gravels
• Lithofacies (Middle): Mud
• Lithofacies (Lower): Clay, Silt
• Lithofacies (Lower, Minor): Sands, Gravels

• Thickness: 50 - 60 m or thinner
• Lower limit: Conformity? (Yasugi Formation, Sakaiminato Formation), Unconformity (Sashimi Formation, Daikonjima Basalt, Eshima Basalt)

• Distribution: Lake Nakaumi - Lake Shinjiko, Shimane pref. - Tottori pref.; Daikon island - Eshima island, Yatsuka village, Matsue city, Shimane pref.; River mouth of Kandogawa river - river mouth of Hikawa river, Izumo city, Shimane pref.
• Fossils: Echinoids
• Fossils (Shellfishes): Anadara broughtonii, Anadara granosa?, Anadara subcrenata, Brachidontes senhausia, Cerithidea djadjariensis, Corbicula japonica, Dentalium hexagonum, Dosinia penicillata, Fulvia kungerfordi, Fulvia mutica, Fusinus perplexus, Lucina stearnsiana, Macoma incongrua, Nassarius eivescens, Paphia undulata, Pecten albicans, Polinices reiniana, Potamocorbula amurensis, Raeta pulchella, Tapes variegata, Theora lubrica, Trisidos tortuosa kiyonoi, Tritia festiva, Veremolpa micra

• Sawada et al. (2009) Jour. Geol. Soc. Japan, vol.115, Supplement, pp.51-70 DOI
• Kano et al. (1998) Geology of the Taisha District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 58p. (in Japanese with English abstract 3p.)
• Kano et al. (1994) Geology of the Matsue District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 126p. (in Japanese with English abstract 5p.)
• Kano et al. (1991) Geology of the Imaichi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 79p. (in Japanese with English abstract 5p.)
• Kano and Nakano (1985) Geology of the Mihonoseki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 28p. (in Japanese with English abstract 3p.)
• Kano and Yoshida (1985) Geology of the Sakaiminato District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 57p. (in Japanese with English abstract 5p.)