Maekawa Formation

Type locality: Maekawa river, Oshu city, Iwate prefecture
Coherent formation
Miocene
Correlation: Onnagawa Formation

Sedimentary facies: Marine
Lithofacies: Sandy siltstone, Shale, Sandstone
Lithofacies (Minor): Tuff, Tuffaceous sandstone

Thickness: 400 - 450 m
Upper limit: Conformity (Orose Formation), Unconformity (Ichinonohara Tuff Member, Mizuyama Formation)
Lower limit: Transitional (Oidegawa Formation)

Maekawa Formation
[ Upper ]
--------------
Main part
'''''''/,,,,,,
Kosamuzawa Tuff Member
'''''''/,,,,,,
Main part
--------------
[ Lower ]

Mount Yakeishidake, Iwate pref.
[ Upper ]
~~~~~~~~~~~~~~
Mizuyama Formation
~~~~~~~~~~~~~~
Orose Formation
--------------
Maekawa Formation
--------------
Nishikozawa Formation
'''''''/,,,,,,
Oidegawa Formation
--------------
Oarasawa Formation
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: Maekawa river - Shitomae river - Orose - Isawa river, Oshu city, Iwate pref.; Iwai river, Matsurubedaira, Ichinoseki city, Iwate pref.; Onikabe creek - Kitamata river, Ichinoseki city, Iwate pref.
Fossils: Sponges (Makiyama chitanii), Foraminifera (Cyclammina japonica, Globoquadrina altispira altispila)
Fossils (Shellfishes): Calyptogena nipponica, Cerastoderma cf. shinjiense, Chlamys crassivenius, Chlamys kagamianus, Delectopecten sp., Lucinoma cf. acutrilineata, Patinopecten kimurai ugoensis

Kitamura (1965) Yakeishi-dake, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 40p. (in Japanese with English abstract 8p.)