Jo Formation

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Jo Formation

Coherent formation
Pliocene - Pleistocene

Sedimentary facies: Marine
Lithofacies: Sands, Mud, Gravels
Lithofacies (Lower, Minor): Pyroxene andesite volcanic breccia, Tuff

Thickness: ca. 3 - 200 m or thicker
Upper limit: Unconformity (Shimoomi Basalt)
Lower limit: Unconformity (Omi White Tuffs, Shimokamo Sandstone, Ishiki Formation)

Jo Group
[ Upper ]
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Shimoomi Basalt
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Asahidaki Basalt
~~~~~~~~~~~~~~
Ono Formation
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Jo Formation
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: Jo - Omikawa river, Nakaomi, Izu city, Shizuoka pref.; Ikadaba - Hinata - Umegi, Izu city, Shizuoka pref.; Shimoda - Suzaki, Shimoda city, Shizuoka pref.
Fossils, Shellfishes

Sumi (1958) Mikomotojima, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 33p. (in Japanese with English abstract 6p.)
Sawamura (1955) Shuzenji, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 47p. (in Japanese with English abstract 4p.)