- U1, Chiba pref.
- U-1, Toyama pref.
- U2A
- U2A'
- U2B
- U3A
- U3B
- U4
- U4.5
- U5
- U6A
- U6B
- U6C
- U6D
- U7
- U7.5
- U7.6B
- U8
- U9
- U9.2
- U10A
- U10B
- U11
- U12
- U-I Formation, Himenoura Group
- U-II Formation, Himenoura Group
- U-IIa Member, Himenoura Group
- U-IIb Member, Himenoura Group
- U-IIb1 Member, Himenoura Group
- U-IIb2 Member, Himenoura Group
- U-IIb3 Member, Himenoura Group
- U-III Formation, Himenoura Group
- U-IIIa Member, Himenoura Group
- U-IIIb Member, Himenoura Group
- U-IIIc Member, Himenoura Group
- U-IV Formation, Himenoura Group
- U-IVa Member, Himenoura Group
- U-IVb Member, Himenoura Group
- U-IVc Member, Himenoura Group
- Ua, Haborogawa Formation
- Ua, Kashima Formation
- Ua, Lower, Ontake volcano
- Ua, Upper, Ontake volcano
- Uf, Kashima Formation
- Uf, Ontake volcano
- Uh, Haborogawa Formation
- Uh, Kashima Formation
- Uh, Ontake volcano
- Unazawa Formation
- Unazawa Unit
- Unazuki Granite
- Unazuki Metamorphic Rocks
- Unazuki zone
- Unit 1, Aso-4 Pyroclastic Flow Deposits
- Unit 1, Daito Formation
- Unit 1, Kashima Formation
- Unit 1, Kourijima Formation
- Unit 1, Kuzu Complex
- Unit 1, Mugi Mélange
- Unit 1, Naha Formation
- Unit 1, Sannomatazawa Pumice Flow Deposit
- Unit 2, Aso-4 Pyroclastic Flow Deposits
- Unit 2, Daito Formation
- Unit 2, Kashima Formation
- Unit 2, Kourijima Formation
- Unit 2, Kuzu Complex
- Unit 2, Mugi Mélange
- Unit 2, Naha Formation
- Unit 2, Sannomatazawa Pumice Flow Deposit
- Unit 2a, Daito Formation
- Unit 2b, Daito Formation
- Unit 3, Aso-4 Pyroclastic Flow Deposits
- Unit 3, Daito Formation
- Unit 3, Kashima Formation
- Unit 3, Kourijima Formation
- Unit 3, Kuzu Complex
- Unit 3, Mugi Mélange
- Unit 3, Naha Formation
- Unit 4, Aso-4 Pyroclastic Flow Deposits
- Unit 4, Kourijima Formation
- Unit 4, Mugi Mélange
- Unit 4, Naha Formation
- Unit 5, Mugi Mélange
- Unit 6, Mugi Mélange
- Unit I, Kuga Group
- Unit I, Northern Chichibu Belt
- Unit I, Numazawa volcano
- Unit I, Southern Chichibu Belt
- Unit II, Kuga Group
- Unit II, Northern Chichibu Belt
- Unit II, Numazawa volcano
- Unit II, Southern Chichibu Belt
- Unit III, Kuga Group
- Unit III, Northern Chichibu Belt
- Unit III, Numazawa volcano
- Unit III, Southern Chichibu Belt
- Unit IV, Numazawa volcano
- Unit IV, Southern Chichibu Belt
- Unit V, Southern Chichibu Belt
- Unit A-1, northern Chichibu Belt
- Unit A, Tokachidake volcano
- Unit B-1, northern Chichibu Belt
- Unit B-2, northern Chichibu Belt
- Unit B-3, northern Chichibu Belt
- Unit B, Tokachidake volcano
- Unit C, Tokachidake volcano
- UNK-9
- UN-MD2
- Unohana Alternation of Sandstone and Shale
- Unokawa Complex
- Unokawa Formation
- Unoke Terrace Deposits
- Unoki Metamorphic Rock
- Unoki Terrace Deposit
- Unzen 1993 Lahar Deposit
- UP, Saitama pref.
- UP, Kanagawa pref.
- Upper Akakuzurezawa Lava
- Upper Akan Pumice Flow Deposit
- Upper Akazawagawa Lava
- Upper Basalt Lava Member
- Upper Eboshidake Lava
- Upper Fluvial Terrace Deposits, Minauchi
- Upper Formation, Maizuru Group
- Upper Formation, Mifune Group
- Upper Formation, Sasayama Group
- Upper Formation, Suzuka Group
- Upper granitoids, Hidaka Plutonic Rocks
- Upper Haborogawa Formation
- Upper Hijochi Formation
- Upper Himenoura Subgroup
- Upper Hiuchidake Lava
- Upper Igarashi Lava
- Upper, Ikeda Group
- Upper Kanamuro Conglomerate
- Upper Kanegasaki Terrace Deposit
- Upper Kanomatagawa Lava
- Upper Karitasan Lava
- Upper Lignite-bearing Member
- Upper Mashu-b Tephra Formaiton
- Upper Mashu Tephra Formation
- Upper Member, Bangamoriyama Formation
- Upper Member, Hashikadani Formation
- Upper Member, Hayaguchigawa Formation
- Upper Member, Kameyama Formation
- Upper Member, Kaneyama Formation
- Upper Member, Kodomari Formation
- Upper Member, Mitsuya Formation
- Upper metamorphics, Hidaka Metamorphic Rocks
- Upper Mitsumineyama Lava
- Upper Mizusawa Lava
- Upper Morita Pumice Tuff Member
- Uppermost, Ikeda Group
- Uppermost Fluvial Terrace Deposits, Minauchi
- Upper Most part, Osaka Group
- Uppermost part, Sekibutsu Tuff Member
- Upper Mudstone Member, Kawaruppu Formation
- Upper Myojin Lava
- Upper Nakashumbetsu Tephra Formation
- Upper Nanakura Tuff Member
- Upper Nasodani Lava
- Upper Nihonmatsu Tuff
- Upper Nojiriko Member
- Upper Odaino Lava
- Upper Ogahana Lava
- Upper Ogane Shell Bed
- Upper Otofuke Formation
- Upper Oya Formation
- Upper part, Akima Formation
- Upper part, Osaka Group
- Upper Pumice Tuff Member
- Upper pyroclastic flow deposit
- Upper part, Sekibutsu Tuff Member
- Upper Sandstone Unit
- Upper section, Mugi Mélange
- Upper Senjogahara Lava
- Upper sequence, Hidaka Metamorphic Rocks
- Upper sheet, Yakuno Ophiolite
- Upper Shibakura Lava
- Upper Shimotamatagawa Lava
- Upper Shingu Sandstone and Conglomerate Member
- Upper Taya Formation
- Upper Tephra
- Upper Teradomari Formation
- Upper Unit, Shiobara-Otawara Pyroclastic Flow Deposit
- Upper unit, Hata Formation
- Upper Wakamiya Formation
- Upper Washidake Lava
- Upper Yabitsugawa Lava
- Upper Yakeyama Lava
- Upper Yezo Group
- Upper Yuzawa Lava