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Kamiizumi Formation (Mitsuchi, 1937) Tokuhashi and Endo, 1984

Invalid synonym: bottom of Kamiiwahashi Formation, lower Miwa Formation

• Type locality: Kamiizumi - Kawaharai, Sodegaura city, Chiba prefecture
• Coherent formation
• Paleo-Tokyo bay fill deposit
• A cycle of marine transgression - marine regression
• Pleistocene (MIS 8 - 7.5)

• Sedimentary facies (Upper): Marine
• Sedimentary facies (Lower): Fluvial
• Sedimentary facies (East): Storm-dominated lower shorefac - inner shelf
• Sedimentary facies (East, Upper): Salt marsh, Inner bay
• Sedimentary facies (East, Lower): Fluvial channel, Flood plain
• Sedimentary facies (Center): River mouth of tidal river
• Sedimentary facies (West, Upper): Transgressive lag, Lower shoreface, Upper shoreface, Fore shore, Back shore, Marsh, Flood plain
• Sedimentary facies (West, Middle): Inner bay, Flood plain, Salt marsh, Gilbert-type coarse-grained delta
• Sedimentary facies (West, Lower): Fluvial channel, Flood plain
• Lithofacies (Northernmost): Mudstone
• Lithofacies (East, Upper): Mud, Sandy mud
• Lithofacies (East, Lower): Gravel, Gravel-bearing muddy sand
• Lithofacies (West, Upper): Sands, Mud
• Lithofacies (West, Middle): Sands, Muddy sands
• Lithofacies (West, Lower): Sands, Gravels, Mud
• Sedimentary structures: Upward fining, Reworked shell fossils
• Sedimentary structures (East): Hummocky cross-stratification, Wave dune
• Sedimentary structures (Center): Trough cross-stratification, Herringbone cross-stratification
• Sedimentary structures (Lower): Trough cross-stratification
• Sedimentary structures (Kimitsu city): Wave ripples, Graded bedding, Trough cross-stratification, Planar cross-stratification, Backset cross-stratification, Convolute lamination

• Thickness (Northernmost): 3 m or thicker
• Thickness: 2 - 50 m
• Thickness (Upper): 0.6 - 9.1 m
• Thickness (Middle): 1.9 - 7.1 m
• Thickness (Lower): 18.6 m
• Upper limit: Conformity or Unconformity (Kiyokawa Formation), Unconformity (Nukada Terrace Deposit, Namegata Member, Kenjaku Member, Joso Formation, Kioroshi Formation)
• Lower limit: Conformity or Unconformity (Yabu Formation), Unconformity (Oarai Formation, Taga Group)

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

• Distribution: Southern Kashima terrace, Southern Namegata terrace, Western Higashi-Ibaraki terrace, Kamiizumi terrace, Lake Hinuma, Ibaraki pref.
• Distribution: Kamiizumi - Kawaharai, Sodegaura city, Chiba pref.; Anegasaki, Ichihara city, Chiba pref.; Ogoyama, Kasama city, Ibaraki pref.; Kamihataki - Hiyamizu, Hokota city, Ibaraki pref.; Sonobe river - Takehara - Ogawa - Katori, Omitama city, Ibaraki pref.; Koise river, Ishioka city, Ibaraki pref.; Maeoba, Mito city, Ibaraki pref.; Onuki - Kamiyama - Matsukawa, Oarai city, Higashiibaraki county, Ibaraki pref.; Ichinosawa, Kamigama, Hokota city, Ibaraki pref.
• Fossils: Tree trunks
• Fossils (Upper): Plants (Trapa chinensis, Trapa macropoda), Plant roots, Burrows, Trace fossils (Macaronichnus segregatis)
• Fossils (Upper, Shellfishes): Anadara granosa, Arcuatula senhousia, Babyonia japonica, Batillaria zonaris, Callista chinensis, Cerithidea fluviatilis, Chlamys nipponinsis, Crassostrea gigas, Cylichnatys striata, Dosinia penicillata, Fabulina juvenilis, Fulvia mutica, Glycymeris yessoensis, Leptothyra amussitata, Lucina stearnsiana, Macoma tokyoensis, Mactra sulcataria, Mercenaria stimpsoni, Mitrella smithi, Moerella sp., Odostmia sp., Olivellafabula, Ostrea gigas, Paphia euglypta, Paratapes undulata, Patinopecten tokyoensis, Pecten albicans, Pillucina pisidium, Raeta pulchella, Ringicula doriaris, Ringicula yokoyamai, Saxidomus purpuratus, Siphonalia fusaides, Solemya pusilla, Spisula sachalinensis, Sunetta menstruaris, Tapes variegata var., Theora lubrica, Trapezium lyratum, Tritia festiva, Umbonium costatum
• Fossils (Lower , Shellfishes): Crassostrea gigas
• Fossils (Naka Terrace, Lower Miwa Formation, Diatoms): Achnanthes lanceolata, Actinocyclus ingens, Actinoptychus undulatus, Amphora ovalis, Caloneis bacillum, Cocconeis placentula, Cocconeis placendula var. euglypta, Coscinodiscus marginatus, Coscinodiscus lineatus, Coscinodiscus radiatus, Coscinodiscus nodulifer, Coscinodiscus wailesii, Cyclotella comta, Cyclotella hützingiana, Cymbella cymbiformis, Cymbella sinuata, Cymbella turgidula, Cymbella ventricosa, Denticula seminae, Diploneis ovalis, Epithemia turgida, Epithemia sorex, Epithemia zebra, Eunotia pectinalis, , Fragilaria harrissonii, Fragilaria verscens, Frutstulia rhomboides, Gomphonema acuminatum, Gomphonema acuminatum var. coronata, Gomphonema angustatum, Gomphonema intricatum, Gomphonema subtile, Gyrosigma distortum, Melosira disians, Melosira granulata, Melosira italica, Melosira sulcata, Navicula dicephala, Navicula halophila, Navicula lanceolata, Navicula mutica, Navicula perigrina, Navicula pupula, Navicula rediosa, Neidium iridis, Nitzschia sp., Pinnularia borealis, Pinnularia interrupta, Pinnularia molaris, Pinnularia viridis, Rhoicosphenia curvata, Rhopalodia gibba, Stephanodiscus nigagarae, Surirella sp., Synedra ulna, Tebellaria fenestrata, Thalassionema nitzschioides, Triceratium sp.
• Fossils (West): Plant roots
• Fossils (West, Shellfishes): Scapharca kagoshimensis
• Fossils (West, Diatoms): Achnanthidium spp., Aulacoseira spp., Cyclotella spp., Diadesmis spp., Diploneis smithii, Gomphonema spp., Luticola spp., Navicula sp., Paralia sp., Planothidium spp., Pseudopodosira kosugii, Thalassiosira spp., Tryblionella granulata
• Fossils (West, Pollen): Alnus sp., Cryptomeria sp., Fagus sp., Hemiptelea sp., Picea sp., Quercus sp., Staurosira spp., Ulmus sp., Zelkova sp.
• Fossils (Kisarazu city, Shellfishes): Batillaria cumingii, Batillaria multiformis, Crassostrea gigas, Glycymeris albolineata, Glycymeris yessoensis, Gomphina aequllatera, Mactra chinensis, Olivella fulgurata, Olivella japonica, Pecten albicans, Pseudocardium sachalinense, Ruditapes philippinarum, Siphonalia cassidariaeformis, Umbonium costatum
• Fossils (Kimitsu city, Diatoms): Achnanthes haukiana, Actinocyclus ingens, Actinoptychus senarius, Actinoptychus splendens, Amphora ovalis, Arachonoidiscus ehrenbergii, Campylodiscus spp., Cocconeis placentula, Cocconeis pseudomarginata, Coscinodiscus marginatus, Cyclotella stylorum, Cymbella minuta, Cymbella sinuata, Denticulopsis spp., Diploneis ovalis, Diploneis smithii, Epithemia adosta, Eunotia pectinalis var. minor, Eunotia pectinoalis var. undulata, Glyphodesmis williamsonii, Gomphonema scumiatum, Gomphonema truncatum, Grammatophora macilenta, Melosia ambigua, Melosia granulata, Melosira sulcata, Navicula radiosa, Navicula yarrensis, Nitzschia ampibia, Pinnularia viridis, Rhaphoneis hachiroensis, Rhaphoneis surirella, Rhopalodia gibba, Rhopalodia gibberula, Stauroneis phoenicenteron, Stephanopyxis spp., Synedra ulna, Tabellaria fenestrata, Thalassionema nitzschioides, Thalassiosira oestrupii
• Tephra: Ata-Th, OgP (Ogoyama Pumice Bed = Sugadaira-2 Pumice Bed), Uk (Ukishima Tephra), Km1, Km2, Km3, Km4, Km5, Km6, Km7, Km8, Km9

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