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Ya-4 Tephra Kurokawa et al., 1987
Abbr.: Ya-4
Invalid synonym: Y2
- Type locality: Yamada, Teradomari, Nagaoka city, Niigata prefecture
- Tephra
- Pliocene - Pleistocene
- Lithofacies: Vitreous volcanic ash
- Sedimentary structures: Graded bedding
- Ya Tephra
- [ Upper ]
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- Ya-6
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- Ya-5
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- Ya-4
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- Ya-3
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- Ya-2
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- Ya-1
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- [ Lower ]
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Yamada, Teradomari, Nagaoka city, Niigata pref.
- Kobayashi et al. (1995) Geology of the Kashiwazaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 102p. (in Japanese with English abstract 4p.)
- Kobayashi et al. (1993) Geology of the Izumozaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 91p. (in Japanese with English abstract 4p.)