- 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
- Od
- OD
- Oda
- Oda Andesite Member
- 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
- Odakara Granodiorite
- 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 Member
- Odake Pyroclastic Cone
- Odake Pyroclastic Rocks
- Odake Sheet
- Odamaki Formation
- Oda Mélange
- Odana Conglomerate
- Odana Lava
- Odana Pyroclastic Flow Deposit
- Odana volcano
- Odani Body
- Oda Pumice Flow Deposit
- 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
- Ok
- OK I
- Ok1
- OK II
- OK-2, Niigata pref.
- Ok2, Kanagawa pref.
- OK III
- Ok3
- Ok4
- OK-5
- Okabe Tuffaceous Sandstone
- Okaburi Formation
- Okachigawa Formation
- Okadashimo Formation
- Okada Tephra
- Okago Formation
- Okago Tuff
- Okamachi Formation
- Okama Lava
- Okamotsugawa Complex
- Okamura Formation
- Okamuri Formation
- Okanaka Tuff
- 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
- Oki Gneisses
- Oki Metamorphic Rocks
- 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
- Oki Tephra, Mie pref.
- Oki Tephra, Shimane pref.
- 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 Member
- Okudani Formation
- Okuda Shell Bed
- Okuda Tuff Bed
- Okueyama caldera
- Okueyama Volcanic Complex
- Okueyama Volcano-plutonic Complex
- Oku Formation
- Okugano Body
- Okugawachi Unit
- Okuhara Formation
- Okuhida Pyroclastic Flow Deposit
- Okuhinotsuchi Formation
- Okui Formation
- Okukano Felsic Intrusive Rocks
- Okukawanami Formation
- Okukinu caldera
- Oku-kita Basalt
- Okukito Lava
- Oku-kurobe Granite
- Okumarusawa Granite
- Okumatashiro Granite
- Okumayama Granite
- Okumayama Granodiorite
- Okumine Body
- Okuminezawa Gravel Bed
- Okumino Acid Igneous Complex
- Okumiyayama Dacite
- Okumizuma Tuffaceous Sandstone
- 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
- Okura Pyroclastic Flow Deposits/li>
- 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
- Okutani Formation
- 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 Dorokoro Member
- Older Dune
- Older edifice, Oshima volcano
- Older Fan Deposits, Akita pref.
- Older Fan Deposit, Nagano pref.
- Older Fan Deposits, Aichi pref.
- Older Fan Deposits, Izumo
- Older Haruna Volcanic Dykes
- Older Haruna Volcanic Fan Deposits
- Older Haruna Volcanic Products
- Older Haruna volcano
- Older Higher Terrace Deposits, Tsu
- Older Humic Soil
- Older Inbi stage intrusive rocks
- Older Josho Lake Deposit
- Older Kitadake Volcano
- Older Lower Terrace Deposits, Tsu
- Older Middle Terrace Deposits, Tsu
- 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 Shinodayama Gravel Bed
- 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 Talus Deposits, Tsuge
- Older Terrace Deposits, Nagaragawa river
- Older Terrace Deposit, Taira
- Older Volcanic Fan Deposit, Daisen volcano
- Older Volcanic Fan Deposit, Nekoma volcano
- Older volcano, Daisen 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 Lava, Minami-Hakkoda volcanoes
- Old Tephra Group
- Old volcanoes, Hachijojima volcano
- 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
- Osatsu Complex
- Osatsu Tephra
- Osawa Conglomerate
- 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
- Oshida Conglomerate Member
- 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
- Otaniike Tephra
- 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
- Otoda 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
- Otonashigawamuro Formation
- 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, Ibaraki pref.
- Otsu Formation, Shimane pref.
- Otsujishinden Tephra
- Otsuka Formation, Miyagi pref.
- Otsuka Formation, Kanagawa pref.
- Otsukamiya Granite
- Otsukata Tuffaceous Sandstone
- Otsukigawa Mudflow Deposit
- Otsuku Member
- Otsu Member
- Otsunagi mass
- Otsutsumi Formation