- Ya
- Ya-1
- Ya-2
- Ya-3
- Ya-4
- Ya-5
- Ya-6
- Yabakei Pyroclastic Flow Deposit
- Yabashira Volcanic Rocks
- Yabashira volcanoes
- Yabashirayama volcanic body
- Yabashirazawa Lavas
- Yabayashi Gravel Formation
- Yabe Formation, Kanagawa pref.
- Yabe Formation, Aichi Formation
- Yabe Group
- Yabitsudake Lavas
- Yabitsuzawa Lavas
- Yabu Formation
- Yabuhara Complex
- Yabuhara Formation
- Yabuta Formation
- Yabuta Siltstone Member
- Yabuzuka Formation
- Yabuzuka Terrace Deposit
- Yachidaira Lake Deposit
- Yachi Formation
- Yachiho Formation
- Yachiho-kogen Lavas
- Yachiho Mudflow Deposit
- Yadagawa Formation
- Yadagawa Group
- Yadani Formation
- Yada Sandstone Member
- Yada Terrace Gravels
- Yadawara Conglomerate Member
- Yadorigizawa Formation
- Yae Formation
- Yaemonzawa Lava
- Yaeyama Basalt I
- Yaeyama Basalt II
- Yaeyama Coal-bearing Beds
- Yaeyama Group
- Yaeyama Lava I
- Yaeyama Lava II
- Yaeyama Lava III
- Yaeyama Member
- Yagami Formation
- Yagane Formation
- Yagen Formation
- Yagigahana Formation
- Yagigahana Lava Member
- Yagii Formation
- Yagisawa mudstone
- Yagisawa Mudstone Member
- Yagisawatoge Formation
- Yagisawa Tuff Member
- Yagi Tephra
- Yagiyama Formation, Osaki city
- Yagiyama Formation, Sendai city
- Yago Formation
- Yagori Volcaniclastics
- Yagoto Formation
- Yaguki Granodiorite
- Yaguki Limestone
- Yaguki Metamorphic Rocks
- Yaguradake Quartz Diorite
- Yagyu Granite
- Yahagi Formation
- Yahazudaira Lava
- Yahazudake Mudstone and Sandstone Member
- Yahazugasen Lava
- Yaita Tephra
- Yajiro Complex
- Yajishita Rhyolites
- Yakebe Pumice
- Yakedake Dome Lava
- Yakedake volcano
- Yakedake volcano group
- Yakeishidake volcano
- Yakeiwadani Granodiorite
- Yakeo I Tephra
- Yakeo II Tephra
- Yakeyama volcanic group
- Yakeyama volcano, Akita pref.
- Yakirizawa Lava
- Yakiyama Lava
- Yakumo volcanic rock
- Yakuno Central Subzone
- Yakuno central zone
- Yakuno Complex
- Yakuno Group
- Yakuno Intrusive Rocks
- Yakuno northern zone
- Yakuno North Subzone
- Yakuno Ophiolite
- Yakuno Rocks
- Yakuno southern zone
- Yakuno South Subzone
- Yakuoji Formation
- Yakuoji Mudstone and Sandstone Member
- Yakuoji Siltstone and Sandstone Member
- Yakura Formation
- Yakushidake cauldron
- Yakushidake Lava
- Yakushidake Rhyolites
- Yakushidakeshita Lava
- Yakushidake Volcanic Rocks
- Yakushi Formation
- Yakushigawa Formation
- Yakushima Granite
- Yakushimidaira Dacite
- Yakushisan Andesites
- Yakushiyama Basalts
- Yakushizawamigimata Conglomerate Member
- Yamabe Group
- Yamada Formation, Hyogo pref.
- Yamada Formation, Miyagi pref.
- Yamada Formation, Tokyo
- Yamadagaya Formation
- Yamada Granodiorite
- Yamadanaka Tuff
- Yamadano Formation
- Yamada Sandstone and Conglomerate Facies
- Yamada Sandstone and Conglomerate Member
- Yamada Tephra
- Yamada type, Miyako Granite
- Yamadori Formation
- Yamaga Complex
- Yamagami Formation, Fukushima pref.
- Yamagami Formation, Gifu pref.
- Yamagami Metamorphic Rocks
- Yamagasu Group
- Yamagata Muddy Sandstone Member
- Yamaguchi caldera
- Yamaguchi cauldron
- Yamaguchi Formation
- Yamaguchi Gravel Bed
- Yamaguchi Pumice Tuff
- Yamaguchi Tuff
- Yamaho Mudstone and Tuff Member
- Yamairagawa Formation
- Yamairi Formation
- Yamajari Formation
- Yamakuwayama Lava
- Yamamawari Formation
- Yamami Formation
- Yamami Siltstone Member
- Yamamio explosion crater
- Yamamiya Pumice Fall Deposit
- Yamamoto Formation, Niigata pref.
- Yamamoto Formation, Tochigi pref.
- Yamamotoyama Loam
- Yamanaka Formation
- Yamanaka Gravels Member
- Yamanaka Granite
- Yamanaka Granodiorite
- Yamanashi Gravel Bed
- Yamanishi Formation
- Yamanoi Formation
- Yamanoisshiki Member
- Yamanokami Gabbros
- Yamanokuchigawa Welded Tuff
- Yamanouchi Formation, Nakagawa Group
- Yamanouchi Formation, Mizunami Group
- Yamanouchi Member
- Yamasa Granite
- Yamasaki Formation, Hyogo pref.
- Yamasaki Formation, Nara pref., Pleistocene
- Yamasaki Formation, Nara pref., Cretaceous
- Yamase-domari Lavas
- Yamashiro Granite
- Yamashita Alternation Member
- Yamashita Formation, Miyagi pref.
- Yamashita Formation, Osaka pref.
- Yamasuge Limestone Member
- Yama Tephra
- Yamatogawa Sandstone Member
- Yamato Group
- Yamato Pyroclastic Flow Deposit
- Yamatsuda Formation
- Yamauchi Formation
- Yamauchi Member
- Yamaya Formation, Akita pref.
- Yamaya Formation, Iwate pref.
- Yamaya Formation, Yamagata pref.
- Yamaya Formation, Niigata pref.
- Yamaya Granite
- Yamayakawa Formation
- Yamayatoge Body
- Yamazaki Calcareous Sandstone Member
- Yamazaki Conglomerate Member
- Yamazaki Debris Avalanche Deposit
- Yamazaki Formation
- Yamazaki Gravel Bed
- Yamazumori Lava
- Yambarazaka Alternation Member
- Yamizo Group
- Yamuke Formation
- Yanabe Terrace Deposits
- Yanagida Formation
- Yanagi Formation
- Yanagisawa Formation, Iwate pref.
- Yanagisawa Formation, Niigata pref.
- Yanagisawa Formation, Nagano pref.
- Yanagisawa Mudflow Deposit
- Yanagisawa Pumice Deposit, Iwate pref.
- Yanagisawa Tuff, Miyagi pref.
- Yanaizu Pyroclastic Flow Deposit
- Yanajimayama Mass
- Yanashi Formation
- Yanba Formation
- Yaoromappugawa Formation
- Yaoroshi Tuff
- Yaotsu Granite
- Yarigatake Crystalline Schist
- Yarigatake Metamorphic Rocks
- Yarimi Tuff Member
- Yarimizu Tephra
- Yarisawa Breccia
- Yasemori Lava
- Yashigamine Volcanics
- Yashiki Conglomerate Member
- Yashiki Formation
- Yashiki Mudstone
- Yashimayama Andesite
- Yashio Formation
- Yashiozawakawa Formation
- Yashiro Conglomerate and Tuff Member
- Yashiroda Formation
- Yashiro Formation
- Yashirogawa Debris Avalanche Deposits
- Yashiro Tuff and Conglomerate Member
- Yasuda Formation
- Yasudate Loam
- Yasudate Terrace Deposit
- Yasugawa Group
- Yasugi Formation
- Yasu Granite
- Yasukajigamori Lava Dome
- Yasukawa Formation
- Yasumori Lava
- Yatagawa Granites
- Yatamaru Body
- Yatani Formation
- Yataro Formation
- Yatazodani Group
- Yatazodani Quartz Diorite
- Yateikurasawa Lavas
- Yatoko Lava
- Yatoko Member
- Yatomi Formation
- Yatsu Clay Member
- Yatsugamaruyama Formation
- Yatsugatake Mudflow Deposit
- Yatsugatake volcanoes
- Yatsuka Formation
- Yatsuo Granite
- Yatsuo Group
- Yatsuoyama Pyroclastics
- Yatsushiro Formation
- Yatsushiro Granite
- Yatsushiro Metamorphic Rocks
- Yatsuyama Formation
- Yawata Tephra
- Yazaki Tephra
- Yazu Formation
- Yobito Formation
- Yodate Lava
- Yodo Basalt Lava
- Yodoe Pumice
- Yogo Formation
- Yogosawa Conglomerate Member
- Yoka Formation
- Yokaichiba Formation
- Yokaichi Formation
- Yokaichi Gravels Member
- Yokatsu Formation
- Yokawa Formation
- Yokawa Granodiorite Porphyrite
- Yokawa Tuff
- Yokigaoka I Tephra
- Yokigaoka II Tephra
- Yokigaoka Clays Member
- Yokinzan Mélange
- Yokkaichiko Formation
- Yokoashiyama Lavas
- Yokobatake Alternation of Sandstone and Mudstone Member
- Yoko-dake Alternation of Shale and Sandstone
- Yokodake Basal Lava
- Yokodake Lava, Nagano pref.
- Yokodake Lavas, Aomori pref.
- Yokodake Volcanic Rocks
- Yokojuku Formation
- Yokokabe Formation
- Yokokawa Formation, Nagano pref., Mino Belt
- Yokokawa Formation, Nagano pref., Ryoke Belt
- Yokokawa Formation, Niigata pref.
- Yokokawagawa Metamorphic Rocks
- Yokokura Formation
- Yokokurayama Group
- Yokomagaura volcano
- Yokomuki caldera
- Yokomuki Formation
- Yokonagane Lava
- Yokone Formation
- Yokonetoge Formation
- Yokonuma Formation
- Yokoo Formation, Nagano pref.
- Yokoo Formation, Toyama pref.
- Yokooyama Trachyte
- Yokosawa Formation
- Yokosawa Sandstone and Mudstone Member
- Yokosuka Formation
- Yokosuka-L Tephra
- Yokosuka Tephra
- Yokosuka-U Tephra
- Yokota Formation
- Yokota Granite
- Yokota Granodiorite
- Yokota intrusion
- Yokota Volcano Group
- Yokoteyama Lava
- Yokoyakyo Lavas
- Yokoyama Dacite
- Yokoyama Formation
- Yokoyama Volcanic Rocks
- Yokoyugawa Lake Deposit
- Yokozawa Dacite
- Yokozumi Formation
- Yomiurishindo Andesite
- Yomurakawamuro Formation
- Yonabaru Formation
- Yonago Andesite
- Yonagokimyo Lavas
- Yonago Lavas
- Yonago Tuff Breccia
- Yonagu Formation
- Yonagu Unit
- Yonamine Formation
- Yonegamori Dacite
- Yonegamori Dacite Member
- Yonesato Formation
- Yoneyama Formation
- Yoneyama Tuff
- Yonezawa Lava
- Yono I Tephra
- Yono II Tephra
- Yono III Tephra
- Yono Member
- Yontan Limestone
- YoP-2
- Yoridaizawa Lava
- Yorihata Member
- Yorii Acidic Rocks
- Yorii Conglomerate Formation
- Yorii Formation
- Yorii. Plutonometamorphic Complex
- Yorii Quartz Porphyry
- Yorii Terrace Deposit
- Yorii Welded Tuff
- Yoro Formation
- Yoro Group
- Yoroibata Formation
- Yoroiiwa Lava and Dike
- Yoroiiwa Pyroclastic Flow Deposit
- Yoro Sand Member
- Yoro Tephra
- Yoro-U Tephra
- Yosa Group
- Yosa Terrace Deposits
- Yosawa Formation
- Yoshida Alternation Member
- Yoshida Andesite
- Yoshida Formation
- Yoshidagawa Andesites
- Yoshida Granodiorite
- Yoshida Plutonic Complex
- Yoshida Shell Bed, Arakawa Group
- Yoshida Shell Bed, Kagoshima pref.
- Yoshifu Terrace Deposits
- Yoshigadaira Tuff
- Yoshigasawa Formation
- Yoshihama Formation
- Yoshihama type
- Yoshihara stage
- Yoshii Formation
- Yoshiigawa Formation
- Yoshiki Formation
- Yoshikura Mudstone Member
- Yoshimagawa Composite Mass
- Yoshimagawa mass
- Yoshimi Metamorphic Rocks
- Yoshimo Formation
- Yoshinaga Alternation Member
- Yoshinazawa Formation
- Yoshinodaira Mudflow Deposit
- Yoshino Formation
- Yoshino Granodiorite
- Yoshino Pumice Flow Deposit
- Yoshino Pyroclastic Flow Deposit
- Yoshinoya Formation
- Yoshinoyama Group
- Yoshinoyama zone
- Yoshinoya Member
- Yoshitsuki Formation
- Yoshiwa Group
- Yoshiwara Formation
- Yoshiwara Lava
- Yoshizu Formation
- Yot
- Yotei volcano
- Yotsudake Central Cone
- Yotsudake Lava
- Yotsudake volcano
- Yotsugoya Formation
- Yotsukura Formation
- Yotsuyaku Formation
- Yotsuzawa Formation
- Yotsuzawa Tuff
- Younger Atosanupuri Volcano
- Younger Central Cones, Hakone volcano
- Younger Debris Avalanche Deposits, Tateyama volcano
- Younger Debris Flow Deposit
- Younger Dorokoro Member
- Younger Dune I
- Younger Dune II
- Younger edifice, Oshima volcano
- Younger Fan Deposits, Akita pref.
- Younger Fan Deposit, Nagano pref.
- Younger Fan Deposits, Aichi pref.
- Younger Haruna Volcanic Fan Deposit
- Younger Haruna volcano
- Younger Higher Terrace Deposits, Tsu
- Younger Humic Soil
- Younger Inbi stage intrusive rocks
- Younger Ino Metamorphic Complex
- Younger Josho Lake Deposit
- Younger Kitadake Volcano
- Younger Loam
- Younger Lower Terrace Deposits, Tsu
- Younger Middle Terrace Deposits, Tsu
- Younger Minamidake Volcano
- Younger Obasute Mudflow Deposit
- Younger Okemi Landslide Deposits
- Younger Ontake Tephra Group, Lower
- Younger Ontake Tephra Group, Upper
- Younger Ontake Volcanic Rocks
- Younger Oshima Group
- Younger parasitic cone and crater, Miyakejima volcano
- Younger period, Yatsugatake volcano
- Younger Ring dyke
- Younger Ryoke Granitoids
- Younger Sand Dune, Katamachi Dand Dune
- Younger Sand Dune I, Arahama Sand Dune
- Younger Sand Dune II, Arahama Sand Dune
- Younger Sand Dune Deposits
- Younger sand gravel bed, Kanazawa
- Younger Shigayama Volcanic Rocks
- Younger Shinodayama Gravel Bed
- Younger stage, Shirouma-Oike volcano
- Younger stage 1, Tokachidake volcano
- Younger stage 2, Tokachidake volcano
- Younger stage Hokusatsu Volcanic Rocks
- Younger stage Nansatsu Volcanic Rocks
- Younger Stratovolcano (Akagi Volcano)
- Younger Talus Deposits, Tsuge
- Younger Terrace Deposits, Nagaragawa river
- Younger Terrace Deposit, Taira
- Younger volcanic-cone-building stage (Akagi Volcano)
- Younger Volcanic Fan Deposit, Nekoma volcano
- Younger volcano, Daisen volcano
- Younger Yakedake volcanoes
- Young Iwate volcano
- Youra Formation
- Youra Unit