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Nishihiro Formation

• Coherent formation
• Yuasa - Aridagawa basin
• Early Cretaceous, Aptian

• Sedimentary facies: Brackish, Fluvial
• Sedimentary facies (Upper, Minor): Shallow marine
• Sedimentary facies: Braided river
• Sedimentary facies (Upper, Minor): Estuary, Seashore
• Depth of water: Shallow marine
• Lithofacies (Top): Shale
• Lithofacies (Upper): Sandstone
• Lithofacies (Upper, Minor): Shale, Conglomerate
• Lithofacies (Middle): Shale
• Lithofacies (Middle, Minor): Coal, Sandstone
• Lithofacies (Lower): Sandstone
• Lithofacies (Lower, Minor): Shale, Conglomerate
• Lithofacies (Basal): Conglomerate
• Sedimentary structures: Trough cross-stratification, Planar cross-stratification, Parallel foliation, Ripple foliation
• Paleocurrent: North to South

• Thickness: 400 - 500 m
• Thickness (Top): ca. 20 m
• Thickness (Upper): ca. 150 m
• Thickness (Middle): 100 - 150 m
• Thickness (Lower): 100 - 150 m
• Thickness (Basal): ca. 30 m
• Lower limit: Disconformity (Arida Formation), Unconformity (Kurosegawa Belt, Northern Chichibu Belt)

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

• Distribution: Cape Babe, Nishihiro, Hirogawa city, Arida county, Wakayama pref.; Shiraki - Oura seashore, Yamamoto, Hirogawa city, Arida county, Wakayama pref.
• Fossils (Shellfishes): Astarte cf. subsenecta, Bakevellia pseudorostrata, Bakevellia? cf. shinanoensis, Exogyra sp., Mellania cancellata, Natica (Amauropsis) sanchuensis, Polymesoda (Isodomella) shiroiensis, Polymesoda (Isodomella) shiroiensis var. alata, Trigonia hokkaidoana, Trigonia kikuchiana, Trigonia pocilliformis, Vanikora japonica
• Fossils (Plants): Milssonia schaumburgensis, Plillophyllum pecten, Sphenopteris? sp.
• Fossils (Tree trunks): Cyathocaulis naktonensis, Podocarpioxylon worburnense, Tempshya sp.

• Yao (2012) Jour. Geol. Soc. Japan, vol.118, Supplement, pp.90-106 DOI
• Kase and Maejima (2010) Jour. Geol. Soc. Japan, vol.116, no.5, pp.287-290 DOI
• Hirayama and Tanaka (1956) Kainan, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 62p. (in Japanese with English abstract 12p.)