• C1, Tanohata Granite
• C1, Tephra
• C2, Tanohata Granite
• C3, Tanohata Granite
• C4, Tanohata Granite
• C5, Tanohata Granite

• CA4
• CA5
• Caldera-collapse breccia
• Caldera forming stage, Mashu volcano
• Caldera-forming volcanic rocks, Aso volcano
• Caldera stage, Iizuna volcano
• Caldera stage, Kurohime volcano
• C Alternation of Sandstone and Mudstone Member

• Cbg

• CC5
• CCP5
• C crater, Miyakejima volcano

• Cdn50

• Central cone building stage, Mashu volcano
• Central cone, Higashiyama volcano
• Central cone, Iwakisan volcano
• Central cone, Miyakejima volcano
• Central cone, Tashirodake volcano
• Central cone stage, Kurohime volcano
• Central dikes
• Central part (Hida Belt)

• CGS 1 Tephra
• CGS 2 Tephra
• CGS 3 Tephra
• CGS 4 Tephra
• CGS 5 Tephra
• CGS 6 Tephra

• Ch
• Ch1
• Ch2
• Ch3

• Ch-a
• Ch-a1
• Ch-a2
• Chanai Tephra Formation
• Chashikotsunai Formation
• Chausudake Lava
• Chausudake volcano
• Chausuyama Gravels Member
• Chausuyama Member
• Chausuyama Lava, Utsukushigahara volcano
• Chausuyama Lava, Yatsugatake volcano
• Chausuyama Welded Tuff Member
• Chaya Formation
• Chayagahara Mudstone Member
• Chayagaoka Andesite
• Chayaike Volcanic Rocks
• Chayano Tuff
• Chayanoue Formation
• Chaya Sandstone and Mudstone Member

• Ch-b
• Ch-b1
• Ch-b2

• Ch-c

• Ch-d
• Ch-d4

• Chepotsunai Formation

• Chiba Terrace Deposit
• Chichibu Belt
• Chichibumachi Formation
• Chichibumachi Group
• Chichibu Quartz Diorite
• Chichibu Tonalite
• Chichibu-yama ejecta-bed
• Chichibuyama Pyroclastic Deposits
• Chigase Formation
• Chigaya Formation
• Chihara Formation
• Chiisagata Formation
• Chikarao Formation
• Chikko Formation
• Chikubetsu Formation
• Chikubushima Body
• Chikusa Formation
• Chinen Formation
• Chinen Sand
• Chinen Sandstone Member
• Chinnanzan Unit
• Chino Granodiorite
• Chinomigawa Formation
• Chiran Formation
• Chishaku Terrace Deposits
• Chitose Tuff
• Chiyoda Coal-bearing Member
• Chiyoda Formation
• Chiyoda Tuff
• Chiyosato-bokujo Lavas
• Chiyosato Lava

• Chj

• Choanji Formation
• Chofu Granite
• Chohanyama Lava
• Chojabaru Gravels
• Chojakubo Member
• Chojamori Rhyolite
• Chojanotebako Intrusive Rock
• Choja Terrace Deposit
• Chojayashiki Dacite
• Chojyagahara maar
• Chokai Unit
• Chokai volcano
• Chokan'yama stratovolcano
• Chokeiji Sand Member
• Chokuro Andesites
• Chokushizuka Gravel Bed
• Chomeiji Body
• Chomyoji I Tephra
• Chomyoji II Tephra
• Chonan Formation
• Chonomori Formation
• Chorakuji Basalt
• Chorakuji Sandstone and Conglomerate
• Choshigataki Lava
• Choshigataki Pyroclastic Flow Deposit
• Choshi Group
• Choshikei lava flow
• Choshitani Formation
• Chosugatamayama Lava
• Chosui Lava

• Chuki Complex
• Chuki Group
• Chuokako Lava, Mount Yokodake of Yatsugatake volcano
• Chuseri Pumice Unit
• Chushi Formation
• Chushin Group
• Chuzenji Quartz Porphyry
• Chuzenji-type Acidic Rocks

• Chw
• Chw-1
• Chw-2
• Chw-3
• Chw-4

• City museum Formation

• Ckz

• Climactic stage, Rishiri volcano

• C Member, Gumizaki Formation
• c Member, U-III Formation, Himenoura Group
• c Member, U-IV Formation, Himenoura Group

• Coastal Sand Dune I, Niigata Sand Dune
• Coastal Sand Dune I-1, Niigata Sand Dune
• Coastal Sand Dune I-2, Niigata Sand Dune
• Coastal Sand Dune I-3, Niigata Sand Dune
• Coastal Sand Dune I-4, Niigata Sand Dune
• Coastal Sand Dune II, Niigata Sand Dune
• Coastal Sand Dune III, Niigata Sand Dune
• Coastal Sand Dune III-1, Niigata Sand Dune
• Coastal Sand Dune III-2, Niigata Sand Dune
• Complex Ia
• Complex Ib
• Complex Ic
• Complex Id
• Complex III

• CP
• CP13
• CP14
• Cpl
• CPm

• Cr
• CR
• Crater lake deposit, Akita-Komagatake volcano
• Crystal ash

• Csn20

• C Tephra
• Ctg
• Ctwg

• Cu