• O1, Omatsuzawa Formation
• O1, Toyama pref.
• O1, Ishikawa pref.
• O1, Chiba pref.
• O2, Miyagi pref.
• O₂, Toyama pref.
• O2, Chiba pref.
• O3, Chiba pref.
• O3, Ishikawa pref.
• O4
• O4.5
• O5
• O6, Miyagi pref.
• O6, Chiba pref.
• O7
• O8, Miyagi pref.
• O8, Chiba pref.
• O10
• O11
• O12
• O13
• O14
• O15
• O16
• O18
• O18L
• O19
• O21
• O22
• O24
• O26
• O27
• O28
• O29
• O30
• O31

• OA
• Oamamiyama Group
• Oamamiyama Volcanics
• Oana, Miyakejima volcano
• Oana Unit
• Oanayama Conglomerate Member
• Oanayama Member
• Oanayama Sandstone and Conglomerate Member
• Oarai Formation
• Oarasawa Formation
• Oashi Formation
• Oa Unit

• OB
• Ob1
• Ob2
• Ob4a
• Ob4b-1
• Ob4b-6
• Ob4c
• Ob5.6
• Ob5.7
• Ob5a
• Ob5aU3
• Ob5c
• Ob6a
• Obadaingawa Complex
• Obadaingawa Formation
• Oba Gravel
• Obama Formation
• Obanashi Complex
• Obaradai Loam
• Obaradai Pumice
• Obaradai Sand and Gravel Formation
• Obaradai Terrace Deposit
• Obara Granite
• Obara Tonalite
• Obasute Mudflow Deposit
• Obata Formation
• Obatake Formation
• Obatake Granodiorite
• Obayashi Formation
• Obg
• Obiki Unit
• Obirakiyama Pyroclastic Rocks
• Obirakiyama Rhyolite Member
• Obirakiyama Tuff
• Obisagawa Member
• Oboke nappe
• Oboke Unit
• Oboke Unit, after Aoki, 2019
• Obonai Body
• Obonai Formation
• Obonai Granodiorite
• Obonai Pluton
• Obonai Pyroclastic Flow Deposit
• Oboradani Formation
• Obora Formation
• Obora Pumice Flow Deposit
• Obp
• Obr-Bnd1
• Obukadake Lava
• Obukadake volcano
• Obuke Tephra
• Ob Unit
• Obusuma Group

• Occhizawa Formation
• Ocg
• Ochiai Conglomerate Formation
• Ochiai Formation, Iwate pref.
• Ochiai Formation, Kanagawa pref.
• Ochiaigawa Shell Bed
• Ochiai Granite
• Ochiai Granodiorite
• Ochiai Lake Deposit
• Ochiai Sandstone Conglomerate Member
• Ochi Formation
• Ochigawa Formation
• Ochi Group
• Ochii Gravel Bed
• Oc Unit

• Od
• OD
• Oda
• Oda Formation
• Odagoe Formation
• Odai caldera
• Odaino Pyroclastic Flow Deposit
• Odaira Formation, Iwate pref., Carboniferous
• Odaira Formation, Iwate pref., Pliocene
• Odaira Formation, Yamagata pref.
• Odaira Group
• Odairakita Lava
• Odaira Lava
• Odaira Pyroclastic Flow Deposit
• Odaira Welded Tuff
• Odakakogen Sandstone Member
• Odake 1st-stage Lava
• Odake 2nd-stage Lava
• Odake 3rd-stage Lava
• Odakegawa Lavas
• Odake Lava, Hakkoda volcano
• Odake Lava, Akita-Komagatake volcano
• Odake Lava, Yatsugatake volcano
• Odake Pyroclastic Cone
• Odake Pyroclastic Rocks
• Odake Sheet
• Odamaki Formation
• Oda Mélange
• Odana Conglomerate
• Odana Lava
• Odana Pyroclastic Flow Deposit
• Odana volcano
• Oda Pyroclastic Flow Deposit
• Odogamori Dacite
• Odoji Formation
• Odokorogawa Formation
• Odoriba Formation
• Odorigawa Formation, Metamorphic rock
• Odorigawa Formation, Rhyolite
• Odorigawa Rhyolites
• Odori Pyroclastic Flow Deposit
• Odori Tephra
• Odose Formation
• Odoshimazawa Pyroclastic Flow Deposit
• Odp

• Oeyama Mass
• Oeyama Ophiolite

• OFN1
• OFN2
• OFN3
• Ofuchi Formation
• Ofudo ignimbrite
• Ofudo Pumice Tuff
• Ofuji Lava
• Ofuku Member
• Ofuna Formation
• Ofuna Mudstone Formation
• Ofunato Group
• Ofunato Subbelt

• Og-3
• Oga
• Ogahana Lava
• Ogamata Formation
• Ogamata Unit
• Ogamo Rhyolite
• Ogane Formation
• Ogane Mudstone
• Oganomachi Formation
• Oganomachi Group
• Ogano Terrace Deposit
• Oga pmt
• Oga Pumice Tuff
• Ogarasu type
• Ogasa Group
• Ogasayama Gravel
• Ogata Basalt Member
• Ogato Lava
• Ogawa Formation, Togakushi, Nagano pref.
• Ogawa Formation, Iiyama, Nagano pref.
• Ogawamachi Group
• Ogawame Agglomerate Member
• Ogawa Tephra
• Ogawa Tuff
• Ogawauchi Tuffaceous Sandstone Member
• Ogawazawa Formation
• Ogaya Formation, Niigata pref.
• Ogaya Formation, Gifu pref.
• Ogayu Body
• Ogigakura Tuff
• Ogikubo Formation
• Ogikubo Sandy Mudstone Member
• Ogikubo Tuff
• Ogino Formation
• Oginohama Formation
• Oginohama Group
• Oginosen Volcanic Rocks
• Ogi Quartz Diorite
• Ogitazawa Andesite
• Ogochi Group
• Ogo Formation
• Ogo Pumice Flow Deposit
• Ogoto Clays Member
• Ogoto-Ogi
• Ogoto Sands Member
• Ogp-b
• Oguchigawa-Kumanogawa Plutonic Rock
• Ogume Sandstone Member
• Oguni Andesite
• Oguni Formation, Yamagata pref.
• Oguni Formation, Niigata pref.
• Oguni Lacustrine Formation
• Oguninuma caldera
• Oguradani Clayslate Member
• Oguradani Formation
• Oguradani Granite
• Ogura Formation
• Ogura Welded Tuff Member
• Ogurayama Group
• Ogurogawa Formation
• Ogusuyama Tephra
• Ogy

• Oh1
• Oh2
• Oh3
• Oh3-1
• Oh3-2
• Oh4
• Oh5
• Oh6
• Oh7
• Oh1
• Oh1
• Oh1
• Oh1
• Oh1
• Oh1
• Oh1
• Oh1
• Oh16A
• Oh16B
• Oh17
• Oh18
• Oh9
• Ohachidaira Caldera Eruption Deposit
• Ohachimori Amphibolites
• Ohagi Gravel Bed
• Ohama Formation
• Ohama volcano
• Ohami Terrace Deposit
• Ohanabeyama Lava
• Ohanayama Andesites
• Ohara Complex
• Oharadani Welded Tuff
• Ohara Formation
• Oharakokushoku Lava
• Ohara Lava
• Ohara Lava I
• Ohara Lava II
• Oharano Formation
• Ohara Pyroclastic Flow Deposit
• Ohara Pyroclastic Flow Deposit I
• Ohara Pyroclastic Flow Deposit II
• O'hara Tonalite
• Ohashi Formation
• Ohata Formation
• Ohatagawa Green Tuff Member
• Ohatayama Lavas
• Ohatayama Pyroclastic Rocks
• Ohayama Formation
• Ohbandai volcano
• Ohchi Formation
• Ohgi Body
• Ohgi Granodiorite
• Ohgi Tonalite
• Ohibara-type Granites
• Ohira I Tephra
• Ohira II Tephra
• Ohira Formation
• Ohirayama Formation
• Ohirayama Unit
• Ohirota Tuffaceous Mudstone
• Ohisagawa Granodiorite
• Ohisawa Formation
• Ohito Andesites
• Ohno Formation
• Ohno Volcanic Rocks
• Ohodake Andesites
• Ohodake Formation
• Ohori Formation
• Ohorigawa Terrace Deposits
• Ohta Mass
• Ohtaniike Formation
• Ohta Tephra
• Ohyamashimo Formation
• Ohzone Formation

• Oidani Formation
• Oidawara Formation
• Oidegawa Formation
• Oido Formation
• Oido Sandstone Member
• Oido Tuffaceous Sandstone Member
• Oi Formation, Fukui pref.
• Oi Formation, Chiba pref.
• Oi Formation, Mie pref.
• Oigatani Chert-Limestone
• Oigawa Group
• Oigawa Sheet
• Oinokura Lava
• Oinosaka Complex
• Oirase Dacite
• Oirase Formation
• Oirasegawa Pyroclastic Rocks
• Oirase scoria cone
• Oiri Lava
• Oiriyama Lava
• Oiriyamasancho Lava
• Oirizawa Lava
• Oishi Dacite Member
• Oishi Formation, Iwate pref.
• Oishi Formation, Gifu pref.
• Oishi Formation, Wakayama pref.
• Oishigawa Formation
• Oishigawa-futamata Lavas
• Oishigawa Lavas
• Oishigawa Pyroclastic Flow
• Oishigawa Scoria
• Oishigawa Volcanic Rocks
• Oishikawa Sandstone Member
• Oishi Lava
• Oiso volcano
• Oitsukkkui Formation
• Oitsurushiyama Granite
• Oiwa Formation
• Oiwake Formation
• Oiwake Pyroclastic Flow Deposit
• Oiwa Lapilli Tuff Member
• Oiwa Tuff
• Oiwa Tuff Member
• Oizumi Formation

• Oji Formation
• Ojigahata Formation
• Ojigokudani Tuff 1
• Ojigokudani Tuff 2
• Ojika Group
• Ojika Mass
• Ojima Conglomerate and Sandstone Formation
• Ojima Formation, Miyagi pref.
• Ojima Formation, Kagoshima pref.
• Ojirakawa Formation
• Ojirogawa Body
• Ojirogawa Mudflow Deposit
• Ojiroyama Lava
• Ojiya Terrace Deposit
• Ojo Formation
• Ojoin Formation
• Ojoji Tuff Bed
• Ojo Tuff Breccia

• Ok
• OK I
• Ok1
• OK II
• OK-2, Niigata pref.
• Ok2, Kanagawa pref.
• OK III
• Ok3
• Ok4
• OK-5
• Okaburi Formation
• Okachigawa Formation
• Okadashimo Formation
• Okada Tephra
• Okago Formation
• Okago Tuff
• Okamachi Formation
• Okama Lava
• Okamotsugawa Complex
• Okamura Formation
• Okamuri Formation
• Okanaro Group
• Okata volcano
• Okata Basalts
• Okawa Formation
• Okawajiri Lava
• Okawara Alternation Member
• Okawaratoge Pyroclastics
• Okaya Gravels Member
• Okayatani Granodiorite Porphyry
• Okayazawa Mass
• Okazaki Formation
• Okazaki Group
• O-kb1
• O-kb2
• Okemi Tephra
• Okenuma Unit
• Okiagedaira Lavas
• Okimura Formation
• Okinajima Debris Avalanche Deposit
• Okinajima mud flow deposit
• Okinajima volcanic mudflow deposit
• Okinazawa Basalt Member
• Okine Member
• Okinoshima Body
• Okinoshima Sandy Siltstone Member
• Okinoshima Welded Tuff
• Okirai Granodiorite
• Okitsu Mélange
• Okiura Basalt Member
• Okiura caldera
• Okiura Dacite
• Okkai Tephra
• Okkoto Lava
• Okogawazawa Debris Flow Deposit
• Okogawazawa Formation
• Okogawazawa Lavas
• Okozuritani Granodiorite Porphyry
• Oksco
• Okubo I Tephra
• Okubo II Tephra
• Okubo Body
• Okubo Formation, Fukushima pref.
• Okubo Formation, Nagano pref.
• Okubo Lava
• Okubo mass
• Okubo Mudstone and Sandstone Member
• Okubo Mudstone Member
• Okuboyama type
• Okuda Formation
• Okudake Lava
• Okuda Tuff Bed
• Okueyama caldera
• Okueyama Volcanic Complex
• Okueyama Volcano-plutonic Complex
• Oku Formation
• Okugawachi Unit
• Okuhara Formation
• Okuhida Pyroclastic Flow Deposit
• Okuhinotsuchi Formation
• Okui Formation
• Okukano Felsic Intrusive Rocks
• Okukawanami Formation
• Okukinu caldera
• Okukito Lava
• Oku-kurobe Granite
• Okumarusawa Granite
• Okumatashiro Granite
• Okumayama Granite
• Okumayama Granodiorite
• Okumine Body
• Okuminezawa Gravel Bed
• Okumino Acid Igneous Complex
• Okumiyayama Dacite
• Okumyogata Formation
• Oku-Niikappu Body
• Okuniikappu Complex
• Okunikko Rhyolites
• Okunoin volcano
• Okunosawa Formation
• Okunugi Formation
• Okura Andesite Member
• Okura Formation, Niigata pref.
• Okura Formation, Nagano pref.
• Okuramata Formation
• Okurayama Quartz Diorite
• Okuro Lava
• Okuromoriyama Body
• Okusakainosawa Sandstone and Mudstone Member
• Okusayama Mass
• Okuse ignimbrite
• Okuse Pyroclastic Flow Deposit
• Okushibetsu Plutonic Complex
• Okushiga Lake Deposit
• Okushimayama Welded Tuff
• Okusoechi Lava
• Okusoechi Pyroclastic Flow Deposit
• Okutadami Green Tuff Formation
• Okutamadani Complex
• Okuteineyama Lava
• Okutone Granite
• Okutone Group
• Okuwabara Formation
• Okuwa Debris Avalanche Deposit
• Okuwa Formation
• Okuwa Sandstone Member
• Okuwahara Sandstone Member
• Okuwa Mudflow Deposit
• Okuyamada Formation
• Okuyama Debris Avalanche Deposits
• Okuyama Formation
• Okuyama Member, Yamanashi pref.
• Okuyama Member, Toyama pref.
• Okuyama Pyroclastic Flow Deposit
• Okuzu Formation
• Okuzumi Formation
• Okuzure Conglomerate
• Okuzure Formation, Chiba pref.
• Okuzure Formation, Shizuoka pref.
• Okuzure Group

• Old dune, Shonai sand dunes
• Older Akakuradake Debris Avalanche Deposit
• Older Atosanupuri Volcano
• Older Debris Avalanche Deposits, Tateyama volcano
• Older Debris Flow Deposit
• Older Dune
• Older edifice, Oshima volcano
• Older Fan Deposits, Akita pref.
• Older Fan Deposit, Nagano pref.
• Older Fan Deposits, Aichi pref.
• Older Haruna Volcanic Dykes
• Older Haruna Volcanic Fan Deposits
• Older Haruna Volcanic Products
• Older Haruna volcano
• Older Humic Soil
• Older Inbi stage intrusive rocks
• Older Josho Lake Deposit
• Older Kitadake Volcano
• Older Minamidake Volcano
• Older Naeba volcanic products
• Older Obasute Mudflow Deposit
• Older Okemi Landslide Deposits
• Older Ontake Volcanic Rocks
• Older Oshima Group
• Older parasitic cone and crater, Miyakejima volcano
• Older period, Yatsugatake volcano
• Older Pyroclastic Flow Deposit, Iiji volcano
• Older ring dyke
• Older Ryoke Granitoids
• Older Sand Dune, Katamachi Sand Dune
• Older Sand Dune Deposits, Fukui
• Older Sand Dune Deposits, Kisakata
• Older Shigayama Volcanic Rocks
• Older stage, Norikura volcano
• Older stage, Shirouma-Oike volcano
• Older stage, Tokachidake volcano
• Older stage Hokusatsu Volcanic Rocks
• Older stage Nansatsu Volcanic Rocks
• Older Stratovolcano (Akagi volcano)
• Older Stratovolcano (Iwaki volcano)
• Older stratovolcano (Tashirodake volcano)
• Older Terrace Deposits, Nagaragawa river
• Older Terrace Deposit, Taira
• Older Volcanic Fan Deposit, Nekoma volcano
• Older Yakedake volcanoes
• Oldest Fan Deposits
• Oldest plutonometamorphic rocks
• Oldest stage Nansatsu Volcanic Rocks
• Old Fan Deposits
• Old Iwate volcano
• Old Somma Deposits, Hakone volcano
• Old stage, Daisen volcano
• Old stage Lava, Minami-Hakkoda volcanoes
• Old Tephra Group
• Old volcanoes, Hachijojima volcano

• OM1
• OM1-OK III
• Omachi APm
• Omachi Loam
• Omachi Sandstone
• Omachi Tephra
• Omae Unit
• Omaezaki Alternation
• Omaezaki Terrace Deposits
• Oma Formation, Aomori pref.
• Oma Formation, Shizuoka pref.
• Omagari carbonate islet
• Omagari Formation
• Omaki Diorite
• Omama Complex
• Omama Terrace Deposit
• Omanako volcano
• Omata Formation
• Omatagawa Mudstone Member
• Omata Pyroclastic Rocks
• Omatsukura Lava
• Omatsukura volcano
• Omatsuzawa Formation
• Ome Formation
• Omeshi Lava
• Omeshi volcano
• Omichidani Formation
• Omi Complex
• Omig
• Omigawa Formation
• Omigawa Unit
• Omi Granite
• Omika Formation
• Omi Limestone
• Omi Limestone Group
• Omi Metamorphic rocks
• Ominagawa Formation
• Omine Acidic Tuff Bed
• Omine Conglomerate
• Omine Debris Deposits
• Omine Formation, Nagano pref., Pliocene
• Omine Formation, Nagano pref., Pleistocene
• Omine Granitic Rocks
• Omine Granodiorite
• Omine Gravels
• Omine Lava
• Omine Mudstone Member
• Omine-Odai Acidic Igneous Rocks
• Omine-Odai Acidic Rocks
• Omine-Odai caldera
• Omine Pyroclastic Flow Deposit
• Omine Sandstone Shale Member
• Omine Welded Tuff Bed
• Omineyama Formation
• Omineyama Member
• Omi White Tuffs
• Omiya Formation
• Omma Formation
• Omma Sandstone Formation
• Omodani Formation
• Omodani Mass
• Omodani Rhyolites
• Omogawa Formation
• Omokawa Formation
• Omori Formation
• Omoriyama Andesite
• Omoriyama Formation
• Omorozawa Member
• Omotezawa Formation
• Omoto Formation
• Om-SK110
• Omt
• Omuro Lava

• Onabezawa Andesite Member
• Onagadani Pyroclastic Rocks
• Onagane Lava
• Onagata Subunit
• Onagawa Formation
• Onagi Welded Tuff
• Onagurayama Andesite
• Onamedake Lava
• Onamedake Pyroclastic Cone Deposit
• Onarisawa Formation
• Onawashiro Lava
• Onazaka Tuff Member
• Onbara Granite
• Onbasejima volcano
• Onbegawa Tephra
• Onbetsu Group
• On-Byk
• Onenai Formation
• Oneyama Lavas
• On-Fk
• Ongata Formation
• Ongata Tephra
• Onibushi Formation
• Onigajo Lava
• Onigatsuji Mudstone and Sandstone Member
• Onigatsura Volcanic Rocks
• Oniike Formation
• Onikobe caldera
• Onikobe-Ikezuki Tephra
• Onimaru Formation
• Onioshidashi Lava
• Onishibetsu Formation
• Onishi Conglomerate Member
• Onishi Formation
• Onita Formation
• Onitaro Metamorphic Rocks
• Oniu Formation
• Oniu Member
• Onizaki Formation
• Onizawa Stage
• Onizawa-Takayamazawa Pyroclastic Flow Deposit
• Onjuku Shell Bed
• On-Ki
• On-Kn
• On-Kr
• On-Kt
• Onma Formation
• Onma Sandstone Formation
• On-Mt
• Onnagawa Formation
• Onnaiwa Lava
• On-NG
• Ono caldera
• Onoda Formation, Miyagi pref.
• Onoda Formation, Aichi pref.
• Ono Formation, Iwata pref.
• Ono Formation, Fukushima pref.
• Ono Formation, Shizuoka pref.
• Ono Formation, Hyogo pref.
• On-Og
• Onogahara Formation
• Onogahara Group
• Onogawa Hard Shale Member
• Onogawa Formation
• Onogawa Group
• Onogi Formation
• Onomatsuzawa Formation
• Onomi Conglomerate Member
• On-Ot
• Ono Terrace Deposits
• Onozawa Gravel
• On-Pm1
• On-Pm1'
• On-Pm2
• On-Pm2'
• On-Pm3
• On-Pm3'
• On-Sk
• On-Sn
• On-Ss
• Ontake-Byakubi Tephra
• Ontake volcano
• Onuki Formation
• Onuma Formation
• On-Yn
• On-Ys
• Onzawa Facies

• Ooi 1
• Ooi 2
• Ooka Mudflow Deposit
• Oomigawa Formation

• OP
• OP1
• OP2
• Opirarukaomappu Body
• Oppara Formation
• Oppata Granite

• OR
• OR-1a
• OR-1b
• OR-2
• OR-3
• Orakumaigawa Formation
• Oriai Formation
• Oribeyama Formation
• Oridani Granodiorite Porphyry
• Orido Tuff Member
• Origamizawa Formation
• Orikabe-1a type
• Orikabe-1b type
• Orikabe-2 type
• Orikabe-3 type
• Orikabe Quartz Monzonite
• Orikabetoge Formation
• Orikabe type
• Orikabezawa Body
• Orikado Basalt and Mudstone Member
• Oritate Conglomerate
• Oritate-toge Conglomerate
• Orito Formation, Niigata pref.
• Orito Formation, Ishikawa pref.
• Orito Member
• Oritoyama Basalt
• Oritsuki Member
• Oritumedake Fan Deposit
• Oriwatari Formation
• Orobetsu Formation
• Oro Formation, Aichi pref.
• Oro Formation, Kyoto pref.
• Oro Formation, Shimane pref.
• Orojidani Formation
• Orose Formation
• Oroshi Tephra

• OS
• Osadano Formation
• Osafuji Quartz Diorite
• Osagawa Formation
• Osagawa Lava
• Osaka Dacite
• Osakada Gravel
• Osakada Loam
• Osaka Group
• Osakamoto Formation
• Osaka Pyroclastic Rocks
• Osakatoge Complex
• Osakatoge Formation
• Osakawan Formation
• Osakihana Dacite
• Osaki volcano
• Osako Complex
• Osanai Member
• Osanai Tuff Member
• Osarubegawa Formation
• Osarugawa Tephra
• Osarushinai Formation
• Osarushinaigawa Formation
• Osato Group
• Osato Loam
• Osawa Formation, Akita pref.
• Osawa Formation, Miyagi pref.
• Osawa Formation, Yamagata pref.
• Osawa Formation, Sanjo city, Niigata pref.
• Osawa Formation, Uonuma hills, Niigata pref.
• Osawa Formation, Tochigi pref.
• Osawa Formation, Atsugi city, Kanagawa pref.
• Osawa Formation, Hayama city, Kanagawa pref.
• Osawagawa Formation
• Osawa Granite Porphyry
• Osawaguchi Tuff Member
• Osawa Lava Dome
• Osawano Terrace Deposits
• Osawa Pyroclastic Flow Deposit
• Osawa Terrace Deposit
• Osawatoge Formation
• Osawa Tuff
• Osawa type, Miyako Granite
• Osawa volcano
• Osawayama Body
• Osegawa Pyroclastic Flow Deposit
• Osenuma Lavas
• Osg
• Oshidashi Formation
• Oshidomari Formation
• Oshidomari Lava
• Oshidomari-pon'yama Lava Dome
• Oshika Gravel Bed
• Oshika Scoria Group
• Oshikiri Shell Bed
• Oshima Belt
• Oshima Formation, Miyagi pref.
• Oshima Formation, Fukui pref.
• Oshima Group
• Oshima-Kojima volcano
• Oshima Rhyolite
• Oshimatadani Unit
• Oshima Volcanic Rock Member
• Oshima volcano
• Oshimayama Subunit
• Oshimizu Formation
• Oshimojo Formation
• Oshinara Formation
• Oshinuma Formation
• Oshinuma Pumice Group
• Oshinuma Sand and Gravel Formation
• Oshio Formation
• Oshio Pyroclastic Flow Deposit, Chino, Nagano pref.
• Oshio Pyroclastic Flow Deposit, Omachi, Nagano pref.
• Oshi Pyroclastic Flow Deposit
• Oshirabetsu Body
• Oshirabetsu gabbroic complex
• Oshirabetsu gabbroic mass
• Oshirabetsu Plutonic Complex
• Oshirakawa Complex
• Oshirasawa Granite
• Oshiri Granite
• Oshiromori Lava
• Oshiromori Lava Domes
• Oshiromori Volcanic Products
• Oshiromoriyama Lavas
• Oshoro Formation
• Oshosan Lava
• Oshosan products
• Os-Nm
• Osobudani Conglomerate
• Osobudani Pumice Flow Deposit
• Osodani Formation
• Osoki Formation
• Osomaike Facies
• Osone Formation
• Osorezan volcano
• Osoushinai Formation
• Osozawa Formation
• Osozawa Sandstone Member
• Osr
• Os Tuff
• Osuga Tuff Member
• Osumi Granodiorite
• Osuzuyama caldera
• Osuzuyama Acidic Igneous Rocks

• Ot
• Ot1
• Ot1 Unit
• OT10
• Ot2
• Ot2 Unit
• OT21
• OT3
• Ot3 Unit
• Ot4
• OT5
• Otadai Formation
• Ota Formation
• Otagawa Formation
• Otagiri Formation
• Otagirigawa Pyroclastic Flow Deposit
• Otagiri Granite
• Ota Group
• Otakidani Formation
• Otaki Dolerite
• Otaki Formation, Yamagata pref.
• Otaki Formation, Gifu pref.
• Otaki Group
• Otaki Lava
• Otaki Mudstone and Tuff Member
• Otakisawa Body
• Otakisha Lava
• Otakiyama Welded Tuff
• Otakizawa Formation, Aomori pref.
• Otakizawa Formation, Fukushima pref.
• Otakizawa Pumiceous Volcaniclastic Rocks
• Otama Formation
• Otanabe Formation
• Otana Body
• Otani Conglomerate Member
• Otani Formation, Fukushima pref.
• Otani Formation, Niigata pref.
• Otani Formation, Fukui pref.
• Otanigawa Formation, Upper
• Otanigawa Formation, Lower
• Otanigawa Tuff
• Otani Lavas
• Otani Tephra, Aichi pref.
• Otani Tephra, Shiga pref.
• Otaniyama Formation
• Otanoshike Formation
• Ota Pumiceous Volcaniclastic Rocks
• Otarionsen Formation
• Otaru Formation
• Otarunaigawa Formation
• Ota Tephra
• Ota Tuff Member
• Otawara Pyroclastic Flow Deposit
• Otawara Pyroclastic Flow Deposits
• Otbt
• Otchizawa Formation
• Otodani Gabbro
• Otoebetsugawa Formation
• Oto Formation, Fukushima pref.
• Oto Formation, Gunma pref.
• Otogai Tuff Breccia Member
• Otogawa Formation, Toyama pref.
• Otogawa Formation, Aichi pref.
• Otoge caldera, Yamagata pref. - Fukushima pref.
• Otoge caldera, Aichi pref.
• Otoge Cone Sheet
• Otoge Formation
• Otoge Tuff
• Otoge Volcanic Complex
• Otokogawa facies
• Otomari Tuff
• Otomiyama Formation
• Otonashigawa Belt
• Otonashigawa Group
• Otone Formation
• Otonoyama Formation
• Otori Formation, Iwate pref.
• Otori Formation, Fukushima pref.
• Otori Unit
• Otose Formation
• Otose Green Tuff Formation
• Otoyama Tuff Member
• Oto-zan lava flow
• Otozawa Terrace Deposits
• OtP
• Ot pfl
• Otsubo Formation
• Otsu channel
• Otsu Formation
• Otsujishinden Tephra
• Otsuka Formation, Miyagi pref.
• Otsuka Formation, Kanagawa pref.
• Otsukamiya Granite
• Otsukigawa Mudflow Deposit
• Otsu Member
• Otsunagi mass
• Otsutsumi Formation

• Oubayama Formation
• Ouchi Formation
• Oura Formation
• Oura Granite
• Oura Member, upper
• Oura Member, middle
• Oura Member, lower

• Owada Formation
• Owadasawa Lava
• Owa Hornblende-bearing Andesite Member
• Owandawan Conglomerate
• Owani Lacustrine Deposit
• Owarabi Debris Avalanche Deposit
• Owari Coal-bearing Facies
• Owarino I Terrace Deposit
• Owarino II Terrace Deposit
• Owasawagawa Formation
• Owasegawa Tuff
• Owase Group
• Owase-Shirahama Pyroclastic Rocks

• Oyabe Formation
• Oyabe Mudstone Formation
• Oyachi Body
• Oyachi Lava
• Oyachi Member
• Oyachi Tephra
• Oya Formation
• Oyakawa Sandstone and Conglomerate Formation
• Oyakejima Formation
• Oyakisuna Lava
• Oyakkotsu Lava Dome
• Oyama Andesite
• Oyamada Formation
• Oyamadan Granite
• Oyama Formation, Yamagata pref.
• Oyama Formation, Niigata pref.
• Oyama Formation, Kanagawa pref.
• Oyama Formation, Mie pref.
• Oyama Pyroclastic Rocks Member
• Oyama Subgroup
• Oyama Tuffaceous Sandstone Formation
• Oya Mudflow Deposit
• Oyana Formation
• Oyanagawa Formation
• Oyasawa Complex
• Oyashirazu Formation
• Oyatsu white pumice flow deposit
• Oya Volcanic Rocks
• Oyl
• Oyodo Member
• Oyori Mudstone
• Oyori Silt
• Oyp
• OyP
• OyP'
• Oyu Granite
• Oyu Welded Tuff Member

• Oz
• OZ
• Ozaki Formation
• Ozasa Formation
• Ozasa Nuees Ardentes
• Ozasu Tuff Member
• Ozawa Body
• Ozenji Formation
• Ozo Formation
• Ozohara Tephra
• Ozohara Tuff Bed
• Ozone Formation
• Ozono Unit
• Ozuchi Formation
• Ozuchi Tonalite
• Ozuki Tuff and Shale Member
• Ozumi I fossil bed
• Ozumi II fossil bed
• Ozumi Formation
• Ozu Unit I
• Ozu Unit II