Sagashi Formation

Sagashi Formation (Naruse et al., 1951) Suzuki et al., 1990

Invalid synonym: Nakamihara Formation

Type locality: Yamana - Sagashi, Minamiboso city, Chiba prefecture
Coherent formation
Landward slope basin of trench
early - middle Pleistocene

Sedimentary facies: Shallow marine
Lithofacies: Conglomerate, Gravel-bearing mudstone, Gravel-bearing sandstone, Tuffaceous sandstone
Sedimentary structures: Cross stratification

Thickness: ca. 100 - 500 m
Lower limit: Conformity (Hongo Formation), Unconformity (Ishido Formation), Abut unconformity (Kagamigaura Formation)

Chikura Group (Northern part)
[ Upper ]
?--?--?--?--?-
Negata Formation
--------------
Sagashi Formation
?--?--?--?--?-
[ Lower ]

Chikura Group (Southern part)
[ Upper ]
?--?--?--?--?-
Hata Formation
-------'''/,,,
Mera Formation
--------------
Shiramazu Formation
--------------
Shirahama Formation
?--?--?--?--?-
[ Lower ]

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

Distribution: Yamana - Sagashi - Tanabe - Kutsumi - Inawara - Masakihara - Nakamihara - Negata - Kuroiwa - Maura - Mukaihata, Minamiboso city, Chiba pref.; Yokomakura - Kaminotani - Sanno - Maeda - Aiga - Takinotani, Tateyama city, Chiba pref.

Kawakami and Shishikura (2006) Geology of the Tateyama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 82p. (in Japanese with English abstract 5p.)
Suzuki et al. (1990) Geology of the Nago District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 48p. (in Japanese with English abstract 3p.)
Nakajima et al. (1981) Geology of the Kamogawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 107p. (in Japanese with English abstract 7p.)