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Arida Formation

• Coherent formation
• Yuasa - Aridagawa basin
• Early Cretaceous, Barremian (Bivalves)
• Correlation (Limestone): Torinosu Group

• Sedimentary facies (Upper): Marine
• Sedimentary facies (Middle): Marine
• Sedimentary facies (Lower): Terrestrial
• Sedimentary facies (Middle): Fan delta slople
• Sedimentary facies (Lower): Alluvial fan
• Depth of water: Shoreface - Inner shelf
• Lithofacies (Upper): Mudstone
• Lithofacies (Upper, Minor): Limestone
• Lithofacies (Middle): Sandstone
• Lithofacies (Lower): Conglomerate
• Lithofacies (Lower, Minor): Sandstone, Coal
• Paleocurrent: North to South

• Thickness (North): ca. 150 - 250 m
• Thickness (South): ca. 300 m
• Thickness (Upper): 100 - 200 m
• Thickness (Middle): ca. 20 - 70 m
• Thickness (Lower): 30 - 100 m
• Upper limit: Disconformity (Nishihiro Formation, Izeki Formation)
• Lower limit: Conformity (Yuasa Formation, Kitadani Formation), Unconformity (Kurosegawa Belt, Northern Chichibu Belt)

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

• Distribution: Takda, Arida city, Wakayama pref.; Yuasa city - Nishihiro, Hirogawa city, Arida county, Wakayama pref.
• Fossils: Brachopods
• Fossils (Ammonoids): Australiceras aff. argus, Barremites cf. pseudodifficile, Crioceratites (Paracrioceras) asiaticum, Cymatoceras aff. neokomiense, Hamulina sp., Heteroceras aff. astieri, Pseudocrioceras? cf. stentor, Pseudohaploceras japonicum, Shasticrioceras nipponicum, Shasticrioceras cf. poniente, Silesites sp., Toxoceras? sp.
• Fossils (Echinoids): Enallaster cf. böhmi, Enallaster cf. nexilis, Enallaster cf. obliquatus, Enallaster yuasensis, Toxaster sp., Washitaster barremicus, Washitaster macroholucus
• Fossils (Bivalves): Asaphis sp., Astarte aff. subsenecta, Bakevellia haradae, Bakevellia pseudorostrata, Cerithium (Circocerithium) aff. reticulatum, Cerithium sanchuensis, Chlamys sp., Cucullaea acuticarinata, Cucullaea cf. ezoensis, Exogyra sp., Gervillia forbesiana, Gervillia metaforbesiana, Goniomya sp., Grammatodon yokoyamai, Inoceramus sp., Lima cf. ishidoensis, Lucina (Myrtea) cf. ezoensis, Modiola? ishidoensis, Nuculana sanchuensis, Panopaea aff. gurgites, Pecten (Propeamusium) var. yubariensis, Pentacrinus sp., Pinna sp., Plicatula aff. sessilis, Portlandia sp., Spondylus sp., Trigonia hokkaidoana, Trigonia kikuchiana, Turbo sp., Yoldia sp.
• Fossils (Plants): Nageopsis sp., Onychiopsis elongata, Zamiophyllum buchianum
• Fossils (Limestone, Calcareous algae): Girvanella sp., Lithothamnium? sp., Pycnoporidium lobatum, Solenopora rothopletzi
• Fossils (Limestone, Corals): Chaetetopsis crinita, Cladocoropsis mirabilis, Dimorpharaea? sp., Spongiomorpha (Heptastylopsis) asiatica, Stylina higoensis, Thamnasteria yuraensis
• Fossils (Limestone, Stromatoporoids): Stromatopora (Parastromatopora) japonica, Stromatopora (Parastromatopora) kiiensis, Stromatopora (Parastromatopora) memoria-naumanni, Stromatopora (Parastromatopora) mitodaensis

• 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
• Terabe and Matsuoka (2009) Jour. Geol. Soc. Japan, vol.115, no.3, pp.130-140 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.)