[ Top ] [ Japanese ]

Todai Formation Ishii et al., 1953

Invalid synonym (Lower): Ogurogawa Formation

• Type locality: Todai, Hase, Ina city, Nagano prefecture
• Coherent formation
• Upper: Early Cretaceous, late Aptian
• Middle: Early Cretaceous, late Aptian
• Lower: Early Cretaceous, Hauterivian

• Sedimentary facies: Brackish - Shallow marine
• Sedimentary facies: Coast facing open sea
• Sedimentary facies (Upper): Shallow marine, Strong tidal current
• Sedimentary facies (Upper): Shallow marine
• Lithofacies: Sandstone, Mudstone, Conglomerate
• Lithofacies (Basal): Conglomerate

• Thickness: ca. 250 - 300 m
• Distribution (Width): ca. 500 m

• Distribution: Todai - Shobera, Hase, Ina city, Nagano pref.; Oguro river, Ina city, Nagano pref.; Ikenotaira, Takato, Ina city, Nagano pref.
• Fossils: Belemnoids, Echinoids, Plants, Trace fossils
• Fossils (Ammonoids): Diadochoceras nodosocostatiforme, Hypacanthoplites subcornuerianus, Pseudohaploceras
• Fossils (Shellfishes): Cassiope (Cassiopella) angusta, Costocyrena cf. peikangensis, Hayamina naumanni, Isodomella shiroiensis, Nipponitrigonia kikuchiana, Nipponitrigonia naumanni, Nipponitrigonia sakamotoensis, Pterotrigonia kotoi, Pterotrigonia pocilliformis, Tetoria sanchuensis

• Makimoto et al. (1996) Geology of the Takato District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 114p. (in Japanese with English abstract 6p.)
• Kawachi et al. (1983) Geology of the Ichinose District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 70p. (in Japanese with English abstract 6p.)