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(1)‡science Reports. Geological. National. Yokohama. of the. University,. Studies. Petrographical. and. 8,. ⅠⅠ,No･. Sec･. 57. 1961】. the. on. Mountainland. Tanzawa. PartI By Keizo with. 6. MIEAMI. Zllu8tralions. Tables. 3. and. CoNTENTS Introduction. Acknowledgments. outlines. and. Geology. of. stratigrapby. Geomorphology. and. basic. Tanzawa. ∴. ‥. …. ‥. ‥. ‥. -. -. -. -57. ‥.. -. -. -58. -. Acknowledgments. and consists. mountainland. composition. ｡.. ‥‥………‥----------∴99. Introduction. The. ‥. Correlation.････.･･････････.･.･･･････････97. and Structure. Geologic. ‥. ‥--------------･----･-･59 Age. Geologic. …. is intruded. which. by. pyroclastic. a. of. large. a. complex. of. mass. chie且y. of. at. the. quartz-diorite. center.. This. complex,. scale. geosynclinal. latest. Oligocene. As by. compared. its. to. of the. complex. eastern. of. view,. reports.. 1948, region some. the. remain. of. unknown. the. has. above. us. large･. frJom. the. reg”n. is. rocks. of. massif. results. of which. section. feature. the. of. metamorphism a. of. Magna･. /Fossa. the. intense. the. in. uncommon. reglOn･. the. however,. volcanisms, In. complicate･. stratigraphically. studying. TanzaⅥ7a. by. and. addition,. ･causes of this mountainland Accordingly･ of this complex･. both. is characterized. excellent. an. interesting. duri.ng. llighly. been. of. period. complex. condition. writer. of the. of. pyroclastic. complex. the. rocks,. southeastern. products. of the. investigation. the. in the. occurring. unfavourable. geologlCal. since. furnishing. rocks,. surrounding. this. of. structure. the. of the. movement. crustal. graphically to. o壬pyroclastic. tuft series. green. other. the present. units,. accumulation. of. the. during. place. products. in age･. Miocene. geologic. tufE series. tlle development. The the. thick. green. LquartZ-diorite the. other. alteration. so-called. Also. middle. with. unusually. hydrother皿al the. the. the. 1S. series,. took. which. volcanisms to. Misaka. the. as. well-known. from have. on. and. the complex. the been. great. the. topo-. hindrance. the true. natures. petrographically･ distributed. volcano-stratigraphical published. make. in the point. as￣miscellaneous.

(2) 58. K.. The. main. the. and the. scope. tectonic. history. characteristics. by. the. same. The. Tokyo. many. to. the. Thanks the. KATSURA. Of the. due. represented. continued. Saburo. useful. and. encouragement. FtJJIMOTO,. Dr.. to. of Geology. Assistant. KANNO. criticisms. the. Of. with. regard. of. for. of the. =ATAI. deeply. Technology,. of. Mr･. to. and. chemical. indebted. Dr.. Dr.. to. Hitoshi. Takashi. fIAYASfII. KuRASAWA. Hajime. for. university,. Of the. Of the Geologi-. analyses.. writer'sfield for. is also. Tohoku. the. Of. work. Scienti丘c. defrayed. were. Research. by is. the grant. which. greatly. from. the. appreciated. writer.. Tanzawa. Tokyo･. by. down. slopes. and. Tbe. area. tainland, above. and. studied. by part. in the. most. and. the. of the of. its southeast. side. lies the. eastern. numerous. Oiso-hill,. side it is to. ranges. and. 1,000. (over. probably. mountainland･. The. along. rapids,. this. of. valleys,. engraved. gorges,. region. peaks. incised. are. the. of. eastern. southwest.. present. them. Kwanto. the. the. while,. On. lies in the of. from. southwest from. separated River;. which. deeply. and. development. common. to. consists. area. sides. beyond. writer. sharp. mountain. NE-SW･. or. the. are. Sagami-plain.. basin. volcanoes. sea-level) with steepest. of. 65km.,. about. Katura. the. the. Hakone. its main. situated. northeastern. towards. Geomorphology. and. is. course. the Hadano. with. Fuji. and. the. steeply. in contact. Geology. of. mountainland. Its northern. mountainland. EIW. his. lnstitute. Haruyoshi. and. writer. Education･. Expenditure. The. the. discussed. also. alterations. the. for their. Kotora. University. Outlines. the. Prof･. his gratitute. The. Japan,. of. costs. the. To. for. WATANABE,. Prof･. to. Tokyo. University. Goverment. Kagetaka. manuscrlpt･. cal Survery. by. the. petrograpby,. are. paper. work. are. reading. The. and. Of. of Education,. he expresses. present. Tokyo. this. SEIBATA. suggestions･. GoRAI･. institute･. Hidekata. University. valuable. Masao. same. activities. the stratigraphy, In. complex･. volcanic. Prof･. thanks. writer. Profs･. this. of. the. of. is to describe. paper. complex.. Mineralogy, and. this. of. MIEAMI. in height. m.. representing. the falls-all. and. trend. valleys. faults,. many. moun-. resulting large. in. number. The main. eastern part. dissected and. rivers. the. present. by ridge cross. margin belt. a. with the. marginal. a. of of few. ridge part. the. surveyed. lowland peaks nearly. trending aligned at. is divided. area,. NW･SE, in NWISE. right angles, into. several. is separated. wbicb. consists. of. direction･ runnlng. isolated. E-W,. a. from moderately. Many and. blocks.. the. as. valleys a. result,.

(3) Geological. bulk. The. Misaka. the. of. together. series, the. presents. throughout. tainland.. It ranges. small. dykes also on. associated the. rocks. A. margin. of the. Kobotoke. region. of the. adjacent saka. by. series. With. (1888), T.. MuRAEAMI. The. (1932).. to. regard. rocks,. Tbe. the. make 1. Table. series up. the. there. bulk. of. calculated. from. individual. of succession:-. ratios. fossils,. the. columnar. stratigraphic. their in. slate. the. area)･ crops. out ex-. southeastern. throughout. the. is separated. from. to. the. northern Mi-. the. soutbeast･. researches. HoNAqA. (1924). lithologlCal. and. of. T･. and little. are. B･. of. SuzuEI. MITSUCEI be-. known of. similarity. the. rocks･. metamorpbic. conditions.. series,. devoted丘rstly. were. characters the. materials sections unit. by. phyllitic. association. petrographic. of the. metamorphic. mapped. however,. series,. therefore,. of this. and. developed. the. are. (1910), F. this. so-called. mountainland･. the. northwest. series,. of the. mass. phy. unfavourable. the. of. and. from. intrusive. an. rocks. distributed. results. (Geological map), Fig. 2 (Distribution 1 (Stratigraphic succession). Columnar. the quantitative. The. from. Miocene･. distinguished,. It represents. alteration. investigations,. writer's. moun-. compositions･. various. (outside. largely. ra. few. structure,. of this. are. mass. region･. KATO. is part. into. schistose. Stratig. hydrothermal. re-. widely. middle. of basic. eastern. series. same. trending. units. the. there. portion. the. widely. Misaka. topographically. present. which. the. the. mountainland,. line. stratigraphic. complicated. of. this. (1909), T.. of the intense. cause. the. Tanzawa. and. Tanzawa. whole to. region,. present. consisting. tectonic. a. present. from. series. Province,. Izu. Magna･. mostly. consisting. metamorphics. of. of. the. Oligocene. central. of the. schistoslty,. the. eastern. the. south. in. Fossa and. represents. These. complex. tension. of the. contact.. sedimentary. along. unit. the. to. series.. intrusion. of Nakagawa,. vicinity. latest. both. above. rocks. of. region. the. occupying. of the the. from. the. This. lacking. common. and. basic. all belonging. series. southeastern. present. boundary. massif. along. the. lava-flows,. with. western. some. converts. Fig.. 59. is largely. region. actions,. Yugashima. the in the. both. few. a. and. quartz-diorite. the. I. Part. Mountainland,. present. hydrothermal. with. in age. quartz-diorite.. and. by. tuffseries. green. distributes. of. in the. occurring. a鮎cted. Tanzawa. the. on. series.. This. are. rocks. intensely. pyroclastics. Studies. Petrograpbical. and. map. of. the. of. which. are. is described. pyroclastic. make shown below. are. up. in. are. rocks. in. shown each Fig.. in the. in. given. intrusives),. of minor. sections. which. to subdividing. and. Fig･. 3,. stratigraphic 4.. general. order.

(4) 60､. K. I.. Table. Stratigrapbic succession of the the Tanzawa皿Ountainland.. Group. Sub･ ;L.N.. MIKAMI eastern. region. of. FormationMember. (North)イー⊥･･････す(South). group. ■Sekir6zan conglomerate&sandstoJle. 亡 ⊂). ■= (勺. ≡ L∼. EL :⊃ (⊃. (⊃. h. b8. .iコ. 冒. .F2-3･. Nakatuky6tuff. l⊂) >-. ..出. d J三く勺. <. a. a. yunreltOge Nakatuky6. conglomerate&sandstone. 憶s?nuddsstt.onneelrl■. vo】canic･breccia FuflaZaWaforrrlation. Miyagaseformation. Otiaiformation 凸. コ O. J. Zikeformation. ト. bL ..【〕 ⊃ q). Ed >ヽぐq bL) コの. コ ∽. 亡 O. Osawatuff. ≡嘗 ∽L. OLe. Fud6ziridacite-tu庁]. 2080. Karasawatuff 亡. 0. `二: E勺d. Fl. >∈. dL● bJ)O. 1000. tt■J. rd. ?. Nunokawa. 亡t5 め. 【⊃. ∋ ⊂) ト. bD CL コ ⊂). ロコ. volcarlic･breccia. ヽ一. 亡弓. Minoge. ヒ∠. volcanic･breccia. .⊂) コ. I.om.. くβ. Ll. bO. l▼. ed 也. a (勺 N. 亡 cq. ≡ d >1. 守. C). lBodaivolcanic･brecc131. 吋'=. 喜∈. ト. 甘ondanituff.-----[ J. tD旨. Kuzuhavolcanic･breccia. 亡 (勺｢コ c: O. Mizunasivolcanic･breccia. ≡:. sio-izuvolcanic･breccial. d. き. 箪宕. Sjzyuhassetuff. 選書 E. CL コ 0. .コ0. 詮-. lKogusadairarK.g｡sad｡iratuffrdacite-tuff･. L.1. (∫). lKansltivolcanic･breccia. bo +⊃ コ V) U ,b: 也 (勺 bD l⊂). t一. 1= O. = (勺. ∈ L. 0. ･Yadorigituff. t･l.イ. d. a 也 ”. bD. ●こ 0 ーロ (勺. >. Yadorigi ･Kumakivolcanic･breccia volcanic'･breccia.

(5) Geological. Studies. Petrograpbical. and. the. on. Mountainland,. Tanzawa. I. 61. reglOn. re-. Part. '. I. The. Tanzawa the bulk. presents. These. 4.. 1ng. Columnar. and. rocks. section ratios. Kumaki. 2.. Yadorigi Yadorigi. 4.. Kansiti. of pyroclas-. QriglnS･ from. basalt. to. dacite,. and. 21. 河野. 亡十. F:. 20. 打. t< Ol. ” -i. トtI. 9). O ∼. i. 冒. P. volcanic･breccia. 19. ”. 管ロ. Dq ∼ ⊂I. 18. S. tuft. ■⊂l. 管 I,聖賢 P. 5. 6.. Kogusadaira. 7.. Sip:yuhasse. 8.. Mizunasi. 10.. series. P. Tanzawa. volcanic･breccia Kogusadaira tuft. 9.. thick. very. this. of. 宅. ma-. volcanic･breccia. 3.. a. in composition. range. groups.. 1.. is. and. accessory. and. part. southwestern. series,. show-. of the. the. comprlSlng. Aikawa. Misaka. essential. pyroclastic. quantitative. terials. of. the. occupying. of the. largely. tic rocks. Fig.. group. Group. Tanzawa. dacite. 汗絹印. tu庁. E:. tuft. Siomizu. 幹てロ. G. くっー Oq. volcanic-breccia. ll.. Bodai. 12.. Hondani. 13.. Nunokawa. N. rb芹 (p. t<. volcanic-breccia. Kuzuha. P. 【丘. ∈: Oq ?. volcanic-breccia. p. rt崇. a). rl. O ∈: て5. volcanic-breccia. ■■十■. 1T. 8g.曹. 16. E5. tuft. Pq. 1S. P. volcanic-. breccia 14. Minoge. 15. Karasawa. ? Ej. volcanic-breccia. N. ”. 16. 蔓童. ト〕 C). Fud6ziri. 17. Osawa. 18. Nakatuky6. i. tuft. t< P. ロ買. 冒 P. (柁. (β. 1乏. F; ⊂〉 F ”. G. tuff. l⊂!. 叫トづ 0 G PC. volcanic-. ロ]. ぎを. Nakatuky6. and. and. 8. sandstone. 7. conglomerate. A.. and sandstone Lava一且ow. B.. Basaltic. C.. 欝トう Oq ?. to. andesitic. voト. g. 6. 好一. 誉還. 5. 弓. a. ∽. to. andesitic. (杓 P■づ ⊂) ∈. to. andesitic. fine-tuff. coarse-and. l-1. O トづ. Dacitic. F. Black. G. Sandy. tuff. shale tuffand. sandstone. H.. Conglomerate. <. 3. p P一 Cl トi. 2. 邑嘗ロ. E.. 4. tフ`. l⊂!. Basaltic. ?. G. lapilli-tuff D.. 冒首. g監. (⊃l. breccia. Basaltic. 9. P. Sekir6zan. canic. ロ. conglomerate Itid6 mud-. sandstone,. stone 21.. 1(). 賢壷● 弓. tuft. Zytlnreit6ge. ll. 0. breccia. 20.. 13. p. ”. dacite-tuff. 19.. 14･. 弓. 1. ?. and. mudstone. 10. 20. 30. 40. 50. 60. 70. 80. 90. 1009't'. tuffaceous E. F. G. Ⅰi.

(6) 62. K.. are. commonly dykes. small. basalt. of. of basalt,. are. From. also. be. diabase. superposed. these. and. subgroups,. conformably,. each. of. the. view,. in Table. shown them. of. of. lava-凸ows. rocks.. points as. number. few. a. and. pyroclastic. palaeontological. three. A. alterations.. hornblende-andesite,. with. into. hydrothermal. and. associated. divided. are. groups. intense. the. lithological. the. can. group. by. affected. MIKAMI. 1.. present. These. grading. upwards. the. thickness. sub･. into. the. one.. succeeding The. base. of this. is nowhere. group. observed,. and. exceeds. 10,000m. The. present. Aonobara･Susugaya. the. named that. these A.. Te･gatake. total. locality. TyPe dorigi-zawa,. the. ed with. The. :. however,. later.. mentioned. the. of. present. of. dykes. divided. It is. of basic its. and. into. superposed. in the. and. region.. quartz-diorite. be. can. conformably. eastern. numerous. with. subgroup. the. around. mass. 3,400m.. formation. of Yadorigi･. crops. out. It also. for-. one. two. the. upon. north.. the. along. is typically. the. and. This. :. character. thin. (Figs.. zontally. and. This. to. river-side. developed. Ya･. the. of. the. along. upper. of the Kumaki-zawa,. river-course. layers 3. and. from. rocks. Geographical present. around. All. 4).. its. resulting without. east. is widely. large. to. andesite,. of these. rocks. in the. are. in. gradually. extension,. is. different. some. into. injected. of this. convertion. intercalat-. in grain･size. varied. breccias. volcanic. is occasionally. and. tuffs. well-bedded. massive. passes. always. northern. of. lapilli-one. coarse-tuffor. one. mainly. both. the by. hori･ hori･. other.. quartz-diorite. formation. into. various. schistosity.. distribution. region the. and in. consists. lapilli-tufE) and. basalt. dacitic. of. vertically,. its apophyses,. formation tuff, and. coarse-. formation,. bornfelsic. west. It is clear,. Formation. in composition. ranging. the. west. large. a. each. exceeds. Kurokura-gawa. (includingfiine-. and. line. tectonic. a. quartz-diorite.. Lithic. Eons. as. associated. by this. I,. thickness. north. of the. reaches. rocks. intruded. in Table. Yadorigi･zawa. 1). by. group. later･. distributed. widely. Lithologically,. shown. The. described. as. quartz-diorite,. pyroclastic. It is also. as. other.. of. of the. intrusives.. mations,. Aikawa. the. conformable,. is. subgroup. of basic. compositions. minor. line,. originally. borders. complex. from. SubgrotIP. T6gatake. southeastern a. were. groups. Tbe. is separated. group. mass. :. This. formation. distributed of the. over. quartz-diorite,. the. occupying the. from. area. and. so. far. western. north as. can. part to. of. southbe. lob-.

(7) Geological. it represents. Served･. it is intruded as. far. into. grades. Sizyubasse-gawa. uniformity,. the. Yadorigi-zawa,. one,. it strikes. to. the. they The. are. close. strata. of. to. Along mation. the. :. description Ktlmaki. present. belonging. The. NE-SW faults,. the. to. formation. NE-SW. and. it is. sometimes. Probably. axis. of the. with dipping. of the. over-. complicated forms.. Yadorigi-zawa formed. was. in. quartz-diorite.. Eurokura-gawa,. of the. high. even. folding. this. northern with. so. of. E-W. southern. the. idealized. in the river-bed. in. the. trend. in somewhat. map. valley. dislocations. structure. rather. eastwards.. compared. the. and. geological. invasion. 2,000. to. by. a. the. along. dislocations,. these. westwards a. has. steeply. area. caused. of. numerons. present. river-course. the. thickness. for-. the. of. m.. formation,. present. into. subdivided. so. with the. exceeds. Division. are. the. folded. result. dips. and. in the. faults. having. in the. shown. by. Adjacent. faults. relation. a. structure. are. gently. the. of. formation. present. trend. disturbed. is deviated. southeast.. These. turned･ that. As. of this formation a. nearly is much. where. producing. angle. 63. to extend. volcanic-breccia. the. in N-S. it is cut. directions･. extension. I. northwest,. seems. (outside. Kansiti. distribution,. of the. however,. NE-SW. and. half. northern. This. it. southwest,. Yamakita-mati. overlying. In the. group･. in the. Part. formation.. structure;. uniform. the. Mountainland,. Tanzawa. while. Nakagawa,. of. Tanzawa. the. on. of the. part mass,. above. vicinity. It. In the. the. the. Studies. basal. the. by. the. as. region)･ the. be. Petrographical. and. three. lying. members. is given. its lithic character,. to. according conformably. one. can. (Table 1) ;. another. below:-. Volcanic-breccia locality. TyPe kura-gawa. and. It is typically. developed. along. Kumaki-zawa,. both. the. All. rocks. :. the. near. the river-sides border. eastern. of the Kuro･ of the. quartz･. diorite. Lithic entirely. are. It consists volcanic Rarely,. a. above. by. structure. quartz-diorite,. of. volcanic. breccias. the皿OSt. alternation. to. the. present. their. although. are. member. lithic. original. of. containing. typical. basic. blocks. are. fine-. and. is limited. to. various. basic. of. ejecta lapillis of. basalt.. is associated. with. and. coarse-tuft. breccias. Its distribution. and many. the. which. volcanic. Kurokura-gawa. detailed. of. :. belonging. preserved.. mainly. thin. Distribution. turbed. well. rocks,. of the. by. metamorphosed. characters. the. :. character. Kumaki-zawa.. the. faults. from. of this. place. member.. As to. On. place, the. and. the. strike. dip. and. it is di氏cult whole,. junction. the. near. however,. to. are. make it. seems. of. the. much. dis-. clear. the. to trend.

(8) 64. K.. NW-SE. dip. and The. the. eastwards.. member. grades. present. belonging. coarse-tuft. river,-sides. it is. steeply. cut. to. of. from. the. H6kisugi-zawa. the. to. is best. change. seen. In the. from. running. the. fine-tuffand. upper. is. extension. junction. the. of the. Kayanoki-. of the. course. along. northwest,. its southeastern. while. fault. a. the. the Kumaki-zawa.. quartz-diorite, by. of basic. alternation and. and. Yadorigituff. and. thin. a. Yadorigituff,. the. by. the. Kurokura-gawa. into. the Kurokura-gawa. obliquely. separated. MIKAMI. dana-no-sawa. The. Yadorigi. Yadorigi･zawa, Liihic breccia,. The. and. yellowish. tion.. Quartz,. tion, either. the. Yadorigi-zawa. the. map,. basic丘ne-. dark. green,. or. these. owe. and. along. kinds. of metamorphic. bably. the. are. and. massive. the. a. grey,. All. the. being. or. amygdules,. breccias is. alterathe altera-. of. impregnated. are. common-. hydrotbermal products. commonest. of blocks. matrix. intense. to. origin. block. 1api11i and. of these. the. lapilli-. and. amount. small. while. volcanic. coarse･. of the coarse-ash,. coarse-tu乱. crops. repeatedly. (from. the. out. throughout. the. along. Yal-Valley. the. less than. belonging. member from. of the. course. upper. rocks. trending. transforms. quartz-diorite. of this. structure. not. of. to. river-sides Ya6-One. the. of On. 1).. exposed. faults. their. its tributaries. and. member. many. to. of. acidic丘ne･,. it contains. yellowish. member. of. by. river-side. matrix.. intrusion. The. to. up. places,. calcite. in veins. This. :. Fig.. is made. of. the. and. Disiribution. The. breccia. made. occurring. the. along. consists. of basic. some. prehnite. member. layers. In. green;. breccias. present. thin. andesite.. ly of. the. The. volcanic. of purple,. typically. Yadorigi.. character:. lapillis, both. mostly. Kurokura-gawa,. of the. river-course. occurs. member. of. intercalating. of basalt and. This. :. north. (Fig. 4).. tufE. the. Volcanic･breccia. locality. TyPe. 350 m.along. over. localities.. type. of the. one. is. thickness. to. the. is much. northeast. to. the. rocks. of. Yadorigi-zawa. the. present. into. various. actinolite-greenschist-facies.. disturbed,. being. southwest.. The. partly. overturned is pro･. thickness. 550m.. YadorigiTⅥ.ぽ TyPe zawa.. It also Lithic. and. locality. :. type. is developed. character. coarse-tufE. The. with. : an. This. locality along member. occasional. the. is along upper. consists intercalation. the course. chiefly. of the. river-side of the. Kurokura-gawa.. of alternations. of volcanic. Yadorigi-. breccia,. offine-tuff and,. 1apilli-.

(9) Geological. and. tuff. These. sandy. eJeCta. in. ranglng. yellowish. green. directly also. mixed. alternations, grey. colour A. bed. is composed. with. a. and true. structural. disturbance,. distributed. diorite.. In a. verts. the. the. over. into. member. 350m. in the. Sizyuhasse-gawa. 2). locality. TyPe. Nisihadano-mati･. It is. the. of. upper. reaches. Lithic. character. to. those. of. basaltic. occurrence a. also. from. ones. are. always. and. its. continuing This. same. The. The or. riverThis basalts. it impossible. bydrothermal to discrimi-. bulk. the. to. of the southeast. invasion. various. the. around. is. quartz･. the quartz-diorite. of. metamorpbic the. formation. present. con-. belonging. rocks. The. amphibolite-one.. to. total. locality.. is typically. exposed. Futamata-goya developed. to. the. northwest. the. along. the river-course. along. 6kura,. of. of Kansiti-zawa,. gorge. river.. lithofacies formation, and. formation. of the. the. excepting. 3. coarse-tuff(Figs.. black. shale from. transition. coarse･grained. is found the. are. relative. 4).. and. the. among. to. rocks. similar. predominence An. occasional. pyroclastic. to the. sediments. pyroclastic. ssentially. rocks. pyroclastics,. acidic. and. fine-grained. or. gradual.. Geographical of the. well. tuffand. layer･ basic. area. also. the. :. of sandy thin. -as. the. daciticfine-. to. the. varlegated. make. the. type. from. Yadorigi-zawa. of the. somewhat. however,. or. formation. Sizyuhasse-gawa. the. greenish. Formation This. :. above. Sizyuhasse-gawa.. Strong. actinolite-greenschist-facies. thickness. or. north. this. is about. patch.. the. along. andesite.. from. area. eX亡ension,. of. ,mudstones. between. basic. formlng. member. its northⅥ7eStern. part. either. of. This. :. of. lying. lava一点ow(?).. of this. nature. strongly. characteristic. of the. grey,. of. of. angular. is exposed. lava(?). stream. dark. green,. facies(?). Distribution widely. dark. uppear. marginal. cbilled. alteration. the. a. kinds. others.. brecciated. of. intercalated.. 65. strata. chert-like or. I. breccias. the. pebble. display. from. few. a. from. accidental. are. and. comprise. coloured,. commonly. them. layer. of. an. tuffare. They. Mizuhi-no-sawa,. layer. the. and. layer･. thick. somewhat. as. coarse-. distinguishes. which. of the. nate. these. thin. a. brown. breccias. daciticfine･ as. Reddish. of various. basalt,. to. they. ejecta,. up. made. andesite. the. Part. Mountainland,. andesiticfine-tuffderived. them.. of. with. Ocassionally,. from. Besides. each. Tanzawa. the. on. rock畠are mostly. compositiわns. coloured,. under. Studies. pyroclastic. hydrothermally.. affected. are. Petrographical. and. distribution. present. environs further formation,. reglOn. in. :. is. the. north. beyond. this. This. formation. distributed to. the. over. vicinity. the. occupying the. from. area. of Yadorigi. steep. Mt.. in the. mountain Tanzawa southwest,. region.. in its northern. extension,. strikes. nearly. N-S,. and. dips.

(10) K.. 66. moderately to. by. faults. caused. faults. is shifted. being. the. the. even. fold. gentle. NE-SW. with. northern. in the. direction. As. an. the. of. a. result,. NW-SE.. of. Further formation. is. E-W. of. axis. pitching. wings. varies. both. of. side. one.. dislocations. with. upper. numerous. southern. by. inclination. of. by. cut. the present. fold. the. along. gorge. caused. anticlinal. it. formed. was. The. found. is also. axis. Possibly. formation.. preceding. the. faults. angle. the. and. Kansiti-zawa. an. area. is. begins. structure. or. with much,. overturned.. formation.. this. The. east.. sometimes A. of. to. angle. in. resulting. the. trend,. trend. this. formation. with. by. west∇ards. directions,. high. NE-SW. the. of. in. the. compared. course. deviated. NE-SW. disturbed. its general. changes. however,. south,. Here. dislocatio皿in. a. lower. in the. gradually. the. highly. westwards,. formation. south,. to. Sizyuhasse-gawa.. the. of. this. NE-SW,. towards. change. course. Traced. eastwards.. MIKAMI. total. in. the. in intimate. southern. relations. is estimated. thickness. extension. that. with. of. 1,loom.. in. the. formation. can. be. at. locality.. type. Diuision. From. :. into. subdivided. four. relations. graphic. lithologlCal. the. (Table. members. four. the. among. the. view-point,. below,. described. 1), as. are. present. alw`ays. both. gradual,. the. and. strati-. horizontally. and. vertically. Volcanic-breccia. Kansiti. locality. TyPe zawa,. Lithic breccia lateral. of the. of andesite. breccias. of. although. their proportion. breccia.. Sometimes. in. the. Globigerina commonly All 1ets and. sp. and. formation. 'can. seen. yellowish. be. lower. the. junction. Kansitithe. of. 'are. This. to. different. The. affected. and/or. the. 丘eld. as. -a. some. good. these of the. of. ejecta, volcanic found. are. which. volcanic. ･few. contain breccia. is. composition.. hydrothermal. the. representing. A. mudstones. basic. Jquartz. observed. lapillis and. with. horizons. The. 4).. andesite.. of the. matrix. by. in. mixed. chert-like. intensely. member. traced. also. coarse･tuffof. prehnite. the. Yadorigituff,. remains.. volcanic. subangular. of. are. coloured, the. massive. is frequently. of. dominance. according. in. of. lapilli-tuft. green. of calcite, :. at. chiefly. essentially. fine-tuft. brown. foraminifera. rocks. amygdules. Distribution. as. or. of green of these. varies. reddish. manner. same. just. the. lapilli-tuff(Figs.3 and to. the. with. dacitic. to. andesitic. breccia. is composed. basalt. and. consists. offine-tuffand. volcanic. breccia. volcanic. along. situated. member. alternations. transition. The blocks. thin. Futamata-goya. ∼This. character:. with. developed. Sizyuhasse-gawa.. the. and. is well. member. the. of. northeast. Kansiti-zawa. This. :. in abundance.. occur. basal marker.. Vein-. actions.. part. of. the. Besides. ､present the. type.

(11) Geological. locality,. the. Ho上-,. river-beds. the. tI6kisugi-zawa, (2) the branch. of the. Kogane-zawa,. the. Nabewari-zawa,. beds. (5) the. the. (8) the. .gawa,. The. trend. general. Fossils. In. :. the. Sh5-Valley,. and. Ya8-Valley, an. and. the. total. thin. sections,. an. to. is abont. fossils. that. 170m.. river. Sizyuhasse-. the. in the. from. collected. same. of. the. Yado-. the. of. the. river-. Sizyuhasse-. the. of. of. corresponds. thickness the. branch. western. (6). (7) the. tributary. eastern. of the. Kansiti-zawa,. of. branches. the. of. course. upper. Futamata-goya,. of the. of. 6gane-zawa,. cours･e. upper. gorge. 67. tributaries. of the. the. of. of the. this member. of. of the. I. southwest): (1). eastern. 乍ourse. river-bed. Part. to. north. the. river-bed. south. Yal｡-Valley,. (from. middle. course. the. of. (9) the. formation,. ーgaWa. (4). Sh3-,. river-bed. and. Tigi-zawa,. (3.)the. Sizyuhas･se-gawa,. Mountainland,. Ho3-Valley, of the. upper-most. Shュ-, Sh2-,. follows. and. river,. Tanzawa. the. on. as. river-beds. same. of the. of. Ho∑-,. H6kisugi-zawa,. of the. river-side. are. exposures. principal. 1be. a. Studies. Petrographical. and. locality.. type. present. member. vare:. Globigerina. 2;. and. from. collected. chertllike. buried. mudstone. in. breccia.. -volcanic. foraminifera.. Minor. Kogusadaira. reaches. 1; ditto.. Lithic. character. types. this. of. The. :. forming. ･composition, dark monly. an. :ノAndesiticfinemember,. or. green. associated These. Kansiti-zawa.. most. pyroclastic to. predominant. lapilli-tufts. with. du.e. green,. yellowish. the. the. same. are. com-. of. rocks. intense. their. lower. the. along. of the. coarse-tuffare. strata.. well-bedded. observed. branch. eastern. and. are. and. are. outcrops. representative. Kogusadaira-no-sawa,. the. of. Loc.. Tuff. locality. TyPe. rock. 1. Loc.. sp.. bydrothermal. alterations. Distribution 二Kansiti ･a. volcanic-breccia. narrow. to. that. in. the. This. :. area,. of the. to. Kogusadaira. the. of the. Futamata-goya,. east. above-mentioned. dacite-tuffis. total. from. distributed. its general. and The. member.. facies. transitional. trend. within. corresponds. is about. thickness. the. 250m.. locality.. type. Kogusadaira. TyPe. representing. a. member. I)acite･tu征. locality:. The. type. is in the. river-bed. the. of. middle. course. of. the. Kogusadaira-no-sawa. Lithic. :. character. It consists. largely. of thin alterations. intercalations with subordinate of .and coarse-tuff The dacitic coarse-tuft into tufE. grades partly composition.. All. of. the. above. dacitic. pyroclastics. of daciticfine-tuff. andesiticfine･ a are. lapilli-tuft commonly. and. coarse-. the. of. greenish. same or.

(12) K.. 68. in colour,. grey. purplish lowish. The. of. Yadorigi,. and. beyond.. kisugi-zawa.. The its. locality,. their. member. general. trend. member. found. nearly. coincides 125. sp.. greenish. characters. pale. yel-. from. the. the. with. vIClnlty. Of. lapilli-tufF. and. H6-. and. northern. extension_. stratigraphic. positions.. and. Kansiti. that. the. Kansiti-zawa. the. the. on. to. coarse-. represent. conformably. attains. in light. volcanic-breccia, latter.. of the. In. its type･. in thickness.. m.. some. and. foraminifera,. minor. grey,fine-tuft. dacite. of. in thin. located. in the. sections, locali-. type. (Loc. 3). Sizyuhasse. Tuff. locality. TyPe. This. :. Lithic. the. Thin. of. layers the. dacite-tuff,. their. above 3. the. with lying. basalts,. or. pebble. rocks. or. foraminiferan Distribution. The. under. each. in the. :. formation.. reddish former. Palaeozoic. system. present. member. formation, Total. thickness. and. and :. or. coloured dacite-tuff,y. its structure. derived. appearance,. slightly from. com-. an. mixed_. the. strata. the. resembling contains. occupying nearly. commonly basic. coarse-tuffand are. the latter, closely in. variegated is. coarse-tuffof basic. by. marked. somewhat. mudstone probably. are. rocks. green. distributes. 600m.. grey. rocks. same. colored. brown was. of them,. the. of. yellowish. cases.. The. brown,. green. of. in many. of the Sizyuhasse･gawa the. of. pyroclastic. reddish matrix. different.. layer.. basic. yellowish. patch. remains. in the. breccia. a. thin. in. and. Kogusadaira. the. the. intercalated. greenish. of. from. encountered.. ocassionally. or. that. well-bedded. transition. proportions. grey. a. the. while. breccias.. found. as. purplish,. green. conformably. cherty. dark. of. above. in various. of. is often. tu庁are. sandy. river-coursesi. (Fig. 1).. up. gradual. composition. Sometimes. found. Ocassionally,. accidental. and. them. breccias. by. position.. The. same. rocks. 4).. among. abundancy. characterized. breccia. and. is made. member. l､ithologicallyresembles. of the. and. this. the. along. Mizunasi-gawa. of the. and. of. exposed. composition.. pyroclastic. which. andesites. basic. volcanic. intercalated. Most. bulk. lapilli-tuft of the. (Figs.. horizons. is also. The. coarse-tuffof. coarse-tuffto. between. Kansiti-zawa,. character:. fine-tuft and. is typically. member. Sizyuhasse-gawa,. of the. of. of. traced. gorge. of. distinctly. be. dacitic. of courses. upper. petrographic rests. Globigerina. :. the. alternations. from. the. alternations. along. present. Fossils. ty. mostly. can. member. Kansiti-zawa. the. of. Thin. These. of this member. are. pyroclastics. this. of. course. intermittently. out. part. main. lower. the. river-side. and. andesitic. green.. Distribution:. crop. the. while. MIEAMI. a. the greater. corresponds. few. part to. that.

(13) Geological. Petrographical. and. Fossils:. In. thin. Studies. the. on. Tanzawa. Globigerina. sections,. is. sp.. Part. Mountainland,. found. in. I. 69. following. the. localities: Loc.. 4.. bluish. a. The. green. Loc.. andesitic The. 5.. a. Ditto.;. far. northwest. 6kura,. of. found. in. in. andesitic. mudstone. chert-looking. from. cherty. the. central. .血orizon. dykes. and. of this. subgroup,. found. mudstone. superposed. Nil. andesitic. 丘ne･. associated. basic. compositions.. into one. 3,900. formations. two. the. upon. as. The. the. which. total. Hondani-gawa. 1). locality. TyPe. breccia. in. present. descriptions. 1,. Table. thickness. subeach. of this subformations. of these. Lithic. Formation The. :. fine-tuff,. ら(including between. these. and. are. sandstone. are. and. the. massive. lateral. gradual.. intercalated. and. Thin. between. vertical layers. the. lone. being. and. the. the other. northwestern the. exposures. southern of the. formation. area. of. the. caused. by. the. is roughly shifted. block. of. above. by. block. the. transitions dacite-tuff. alternations,. intensely. divided of. I. tuffs. breccia. volcanic. in their upper horizons. All of these rocks _particularly ￣hydrothermally. _ later, distribution : As will be described GeograPhical formation. river-. of well-stratified. alternations. are. ･shifting of the Karasawa-gawa distribution area of the present. the. along. Siomizu-gawa.. by. always. also. developed. lapilli-tuft) and. composition,. pyroclastics. tuffaceous. also. coarse-tuff,. basaltic. to. andesitic. and. is well. of the. It is characterized. :. character. formation. present. liondani-gawa,. of the. The. middle. of volcanic. shown. The. other.. in the north.. m.. by. position,. nu-. with. In the. intercalations. thick. north. below:-. glVen. ･course. rocks,. stratigraphic. conformably about. pyroclastic of. wide一. in the. south.. basin. is. reglOn. in the. two. are. present. Nakatu-gawa. of the. Hadano. the. of. there. subdivided. attains. drainage. lava一旦ows. same. of the. part. of basic. few. a. the. be. can. group. border. accumulation. occupylng. .almost. from也e. area. northern. thick. a. :merous. and. a. occupylng. in the. the. as. It is. Df. from. gathered. subgroup. 二lydistributed. are. Sizyuhasse-gawa,. of the. Oyama白ubgroup. This. group. from. collected. gravel.. B｡. .as. Kansiti-zawa;. of. patch.. .力ne-tuffas Loc. 6. as. gorge. coarse-tuff.. collected a. the. of. river-side. sihadano-mati;. tuft. course. upper. the. altered. westward. movement,. into above. two. the parts:. formation,. one.. formation. distributed. in the. northwestern. area. are.

(14) 70. K.. best. seen. the. along. The. Two. are. T血e. and. folded. gently. formation. of this. Along the. total. Diuision be subdivided are. transitional. The. upper. locality. course. of. variegated. the. of. the. with. in small A. structure. area.. type. the. of. localities,.. the. formation. present. can. inter-relations.. stratigraphic. below:-. developed. the. along. of the･. river-bed. this. basalt. and. consists. These. andesite. their. with. hydrothermal. member. actions. pyroclastic. rocks. a. excess. ∇itb. common. slight. matrix. which. of massive･. of. of. coarse-tuft,. into. them. convert. are. some-. varies of. and. rocks.. mehlber. main. linking. ridge. in different. Kyuha-zawa,. Mt.. to. north. Tanzawa. south. with. Mt.. the. along. T6gatake,.. localities. branch. one. breccias. characterized. andesitewith. the. of by. the Hondani-gawa, lapillis and. dominance. lapilli-tuft of the Sometimes. from. extends. blocks,. latter.. of the. same. composition. the lapilli-tuft contains. it consists,. gravels. each. Thick are. com->. alter-. associated. of granophyre･. amounts.. quite. Xl-Valley,. to the. m.. given. lapilli-tu乱. together. coarse-tuffand. above. of. present. oメfthe. volcanic basalt. blocks. or. The. gorge. massive. nations. are. locality,. subordinate. by. its lithofacies. of. structure. direction,. rocks. :. mid-slope. posed. the. in NE-SW. vertically.. is well. type. the. e]ecta,. affected. Distribution. In. In. with. these. and. strongly. and. 1,700. 1), whose. members. member. :. lapillis. of. eastern. one. of view,. and. Here,. of the･. Siomizu-gawa.. character. composed. what. The. the. breccia. basalt,. of these. :. of. Lithic volcanic. laterally. river-bed. river-･. Volcanic･breccia. TyPe. are. both. descriptions. Siomizu. (Table. members. the. northwestern. is about. lithological point. the. into丘古e. always. formation. of this. From. :. in the. along. contrast. striking. the. out. along. running. Hondani-gawa,. of the. river-course. thickness. presentir)i. a. andalong･. westwards. crops. also. faults. in NE･SW. trending. HadanoISi.. by. is distributed. which. the. disturbed axis,. and. Minoge,. near. N-S. with. southern. its branches,. of Kaname-gawa. area. eas､tern_. and. Mizunasi-gawa,. is shifted. als(>. E.. to. nearly. the. of. formation in the. is much. faults. many. and. its northern. dip. and. reaches. present. and. formation. this. upper. distributed. I(uzuha-gawa. course. upper. of the. part. formation. of. of. a. the. by. Hondani-gawa,. and. N-S. trend. disturbed. in. exposed. lines. Mizunasl-gaWa. ill general,. lines. Siomizu-gawa,. the. of the. of. strata,. dislocation. direction. beds. river-sides. courses. upper. bra‡1Ches･. these. the. along. MIEAMI. breccia. similarvolcanic directly. south. of. the. is also Kyuha-zawa,. exposed and. along. the upper. is associated. course. with. of thick.

(15) Geological. layers. to. of basaltic. The upper. of. basic. breccia,. volcanic. fine-tuft. dacite.. of. of this. It. I. Part. Mountainland,. in. traced. the. Here. it consists. largely. and. coarse-tuft. with. 1apilli-tuft, is intruded. also. be. can. member. Obake-zawa･. of the. course. Tanzawa. the. on. 71. lapilli-tuff･. andesitic. extension. southern. the. Sttldies. Petrographical. and. by. few. a. area. of alternations layers. thin. dykes. along. of. of. micro-uralite-. gabbro. The. present. wards,. forms. member. The. thickness. 450. to. attains. dip. locally. are. locality.. of. the. gorge. 0n. the. map),. dipping. and by. disturbed. type. in the. m.. N-S. trending. monocline. and. strike. althoughits. a. east-. faults･. m?ny. Mi五廿n串帽i Volcanic･breccia locality. TyPe. river-bed. sinkaya-no-sawa,. name,. of. The. :. M5. marked. (another. Karahigo-zawa. of. of the. one. branches. eastern. Mizunasl-gaWa.. the. Lithic type. of this. Massive. :. character. interbedded. member,. is the. breccia. volcanic. thin. with. predominqnt. rock. of basic血e-tuft. and. most. alternations. coarse-tuff. The. and. augite-basalt. coarse-tuft,. densely. are. or. each. composed. into. of in. packed. sporadically. frequently. grades. and. blocks,. lapillis and. of. up. which. -andesite,. of green. matrix. is made. breccia. volcanic. lapilli-tuffof. the. its. same. composition. All. of the. dules丘11ed the. with. coarse-. are. quartz. In. addition,. mudstone. are. often. green. yellowish displays been. a. from. The. representing course. (the Ml-Valley),. an. following. Genzire'-zawa river-course. of the. the. :. the upper. the. ∼present. coloured,. Distribution. from. clastic. grains. amyg-. and. developed. commonly. in. the. lying. throughout. eastern. branch. (the M7-Valley). from to. of Mizunasi-ga甲a,. (3) the. of. the. commonly. north mouth the. Genzir6-zawa,. same. to. these. of. river･ south:. of. the. M91Va11ey,. (4). the. grains. of. have. tuff･. the. with. afore-mentioned. formation,. extends. of the Higo-no-sawa. to the river-bed. the. (2). mudstone. Hondani-gawa. of the. part. of the Mizunasi-gawa. river-beds. Mizunasi-gawa,. together. chert-looking. of. each. under. and. mostly. Some. conformably. basalt. of. fine-tuffis. the. and. colour･. member,. basal. The. composition･ brown. present. gravels. amounts･. small. reddish strata. breccias. abundant. of血e-tu任and. andesitic. characteristic. derived. member,. lapilli-tuffcomprise. and. andesite.. the. or. calcite. prehnite,. Veinlets. hydrothermally･. affected. rocks. The. in. highly. are. rocks. It. can. (1) from. be well the. mouth. Oki･no-genzir6-zawa the To-zawa. northeastern. observed of the along branch. (the M8-Valley),.

(16) 72. K.. Higo-no-sawa.. (5) the. and. At. the丘rst. interbedded. locality,. of basaltic. to. coarse-tuft. is also. dacitic. to. bed. breccia. blocks. of. breccias. usually. The. and. most. the river-bed. the. the. large. and. must. have. fold. In. the. deviates. ､Kuztlha. few. a. the. river･. mingled. with. in. are. in composition. is that. been. from. torn. gravels. in small. of quartz-porphyry. in. exposed. to cobble-sized. pebble-. of. amounts.. derivatives. some. of. Near. breccia. coloured. 監30o,and Bodai. is about. gentle. the. east.. 700m.. to. and The. 40m.. located. It. in. consists. ejecta. of. course. middle. this. a. of. and. in. the. this. of. to to. bed. thin. the. east. or. of. grey. coarse-. The the. of course. middle at. of. layer.. horizon. 皿iddle. dip. member. reddish,. a. is limited. layer. massive. purplish,. horizons. various. its distribution of. the. of. proportions,. intercalated. strata. in. angles. about. in thickness.. Volcanic･br占ccia locality. TyPe Lithic. Volcanic. towards. angles. present a. Hadano-si.. in varying. lenticularly. formation,. attain. Fall. pyroclastic■. intercalated. also is. Sakadati､ of Bodai,. basalts. Kuzuha-由wa･. the. the in. res山ting. member. through. way. faults,. these. NE-SW,. of this. Distribution:. and. and. is. member. Hondani-gawa. the. including. andesites. lapilli-tuft. present. by. with血oderate. thickness. northwest. character. volcanic. to. their. cut. Volcanic-breccia. kuzuha-gawa, Lithic. And. NW-SE. pitching. the. have. to. observed direction･. from. axis. locality,. locality:. TyPe. breccia. the. with. type. are. in NEISW. rocks. gradually. anticlinal. of. granophyre. of faults. number. pyroclastic. member. or. of. rim. exposed. andesite. It contains. gravels. grey. yellowish. breccia. mostly. amounts.. breccia. volcanic. gravels. altered. coarse-tuft,. are. quartz-diorite. A. the. two. the丘rst. These. of volcanic. in small. Higo-no-sawa･. of the. an. dacitic. of. fine- to. green. of. hornblende-bearing. andesite. hornblende-quartz-diorite, Possibly. kind. of. interesting. by. coated. In this. blocks. and. lapilli･tuff, all being. rocks.. gravels basalt･. breccia,. volcanic. intercalation. pyroclastic. few. a. of. and. occasional. these. with. andesite. and. of basalt. An. mainly. coarse-. offine-,. contains. of. in widtb･. M9-Valley,. consists. composition.. associated. composition,. centimeters. member. alternations. andesitic. volcanic. in addition. this. thin. with. The. MIKA班I. :. The. The. :. character. with. river-bed. in. its. matrix. the. upper. of. of. basic. coarse･tuff,. of the. course. is characterized. member intercalations. occasional. breccla,. of. by fine･. comprises. the and. Kuzaha-gawa. massive. volcanic. coarse-tuft. abundant. blocks. The of.

(17) Geological. a few -basalt, and lapilli-tuffor tuff-breccia. into. All. of these is commonly. matrix are. pyroclastic. mostly. tlnged dark. with. Distribution Bodai,. Kuzaha-gawa a. along. lapilli-tuft The. the. extellSi()n. to. basaltic The. N-S. present. 150m.. found. and. Lithic. of. the. It also､ crops massive. coarse-tuff,. is separated. which Daigatake. massive. disturbed. locality.. The. present. and. from. the. with. the main. river-course. of the B2-llValley, breccia. volcanic all. of. where. with. composed. of. sub･. andesitic. by N-S. with. faults. The. axis.. NE-SW. in. running. thickness. or. to. attains. coarse-tuff,. of basalt. pyroclastic. or. to. Distribution as. are. the. Hadano-si, river-beds. B4-Valley),. and of and. It also. the. along. crops. out. along. Besides. follows Kl-Valley,. (from. (2) the. its branches. river-beds. the. abundant. between. coarse-. the above features,. lithological. as. such. dacitic. grey,. of. river-sides. N4-,. N5-,. and. Fits. branches. N6-,. Kaname-gawa. of. Nuno-kawa. the. N3-,. of the. exposures. essential. south): (1) the. river-sides. (the. Kuzuha-gawa,. (4) the. to. north. rocks. are. tufE･. locality,. type. the. in their. pyroclast′ics,. of. intercalated. are. sandstone. (Fig. 3), this. 1. all comprising. laysers. thin. Sizyuhasse. the. pyroclastic. breccia,. volcanic. No.. sections. of various. Sometimes. of these of. columnar. alternations. of. tufEaceous. of. those. the. in the. shown. andesite.. All. :. developed. typically. Obake-zawa.. the. and. lapilli-tuft, and. and. rocks.. similar. As. mostly. lapilli-tuffs,. is. member. Siomizu-gawa. :. fine-tuft,. and. of. where. fine-tuff,. lapilli-tuft,. and. type. character consists. zawa. of. folded. gently. the. of. member. member. Bodai-Pass. in the river-bed. consist. coarse-. Hondani-gawa. of the. river-side. very. north. Tt1ff. river-sides. and. upper. and. rocks.. course. B2-Valley).. with. Mt.. out. is much. member. locality:. TyPe. ejecta. the. mountain-foot. and. the. member,. ]olnnlng. to. of. in the. Hondani. the. calcite. composition.. directions,. about. line. a. intercalations. ordinate. to.. associated. of this. (Fig. 1), crops is. Bodai. be. to. prehnite,. the. along. the ejecta. throughout. the. Bl-. their. colors, while Also. in. (the. often. proportions.. along. Kuzuha-gawa. the. from. green. grey.. observed. 73. hydrothermally;. impregnated. are. branches. extension. fault. a. well. found. in various. southern. by. part. are. path. is. breccia. volcanic. or. I. composition. affected. distributes. member. mountain. or. Part. hornblende-andesite,. same. yellowish. purple,. veins,. its eastern. and. or. reddish and. This. :. its exposures. and. out. green,. the. of. Mountainland,. of. intensely. dark. with. in amygdules. occur. quartz. breccias. are. rocks. Tanzawa. the. on. and. augite-andesite gradillg. Studies. Petrograpbical. and. and. the. near. this. Kyuha1 Moroto,. N7-Valley), (3). the. B2-,. and. (the tBl-, near. of. Minoge,. B3-, and. its.

(18) 74. K.. branches Tbe in. quantitative. and. pyroclastic.. rocks. The. member. general. trend. thickness the. is about. in the northern. predominant, the. of. in. localities, in. while,. same. localities. these the. composition. the. the. one,. southern. exceed. vary. lapilli-tuffof. kinds. other. of. nearly. I,,200. m.. bulk. the. constitutes. to. corresponds the. along. the Hondani-gawa. of. that. river-course. latter.. the. of. formation, The. total. the Siomizu-gawa,. of. one. of. localities.. type. Fossils are. most. found. rocks. in amount.. present. its. Thus. ratios.. fine-tuft. coarse-tuft. Kn4-Valley)... and. pyroclastic. is the. composition. and. Kn皇-, Kn31,. above-mentioned. their. basic. Knl-,. (the. MIEAMI. Under. :. the. fossils. the. microscope,. found. in the. present. member. followsニ. as. Locality. Fossils. Nos. 7. Mother. Localities. Globigerina sp., foraminifers Minor. River-side Kyuha-zawa. A. breecia reddish coloured in tu庁found andesitic丘ne. the. of. desitic Ditto. River･side. of. the. of. the. A. Globigerina. River_side Kuzuha. sp.. of. River-side Eondani-gawa. Ditto. the. of. coarse-. andesitic. crystal･. a also and mudstone lapilli-tuff.. andesitic ll. in andesitic. green,. tuffaceous. mud-. cbert-looking. found. fine-tuff,. ･gawa. gravel found. Light yellowish andesitic tal_vitric fine_tuft.. near. of an_. coarse-tuff.. patch. stone tuff Dark. M9-Valley 9 10. Rocks. of in. crys-. Hondani-. the. bridge. Kara組Wa･gaWa. 2). locality. TyPe. Lithic. rocks. by. horizons terized. by. the. tween. this. the. occurrences. formation. mainly. the. along. basaltic. to. of. river-. is. thick. somewhat. nature. of dacitic from. predominance. lava-且ow. of. pyroclastic. eJeCta. Oyama. the. rocks. is. a. layers.. (Figs.. the. present. found. in. This basic. and. and. sediments. distinctive. feature. of. 3 and. 4)_. ones,. is. one. the is. rock. to the. subgroup. kinds. various. compositions. formation,. of mixed-tuffwhich as. transitional. above. consists. Hondani-gawa. mingling. relative. the. developed. typically. formation. intimate. the. the. is. of andesitic. with. frequent. of. dicating Also. largely. compared. marked. formation. This. character:. pyroclastic As. This. :. Nakatu-gawa.. of the. course. Formation. upper. characIn-. strongly Susugaya. one.. be-. intercalated of this. formation.. (Fig. 4). Geographical extending. from. distribution the. :. river-course. This of. formation the. is. Nakatu-gawa. distributed. over. to. southern. the. the. area. part. of.

(19) Geological. Petrograpbical. Studies. the. formation. and. Tanzawa. the. on. Mountainland,. Part. I. 75. 0yama-mati. At. type,. the. moderately. forming. eastwards,. this. structure. ing. NE-SW,. At. Fudakake. and. present. begins. dip. simple. into. change. tbe｢. and. towards. dips. to. the. the. by. a. faults. sometimes. formation. trend-. overturned･ NE-SW,. strikes to. contrast. sharp. dips. and. however,. numerous. east,. the present. presenting. northwest,. W,. 30o. Southwards,. direction. area. N. nearly. monocline.. N-S. is steep. ill its surrounding. and. steeply. to. a. strikes. the. above. structure.. To. Nunokawa. the. using. Fudoziri. the. and. the above. clarify. structural. its. volcanic-breccia, dacite-tufE-all. layers. associated be. to. proving. formation. the present. relations,. good. traced,. was. of blocky for. markers. lava,. the. pur-. pose.. These. clearly. caused. by. fatllt-block. results. most. and. along the. overttlrn. Of tO. dipplng Such best. was. strata,. in. The. the. also. NW with. northen. limit. from this. of. by. group. NW-SE. structure. takes. formation. found. in the NE. dips. at. side. keeping NE-SW. a. the trend,. striking. area. Fudakake. the. of. are. Karasawa-gawa･ line strikes. of the. side. from. angles. in the. north. southern. a. showing. axis,. just of the. course. middle. and. northern. 5o. 50o･. td. contrast. to. points. of view,. Also. that. it is in. found. side.. considering ern. SE,. to. the. which. TorioISan,. depressed,. and. Nuno-kawa,. distributed. formation. present. folded. the. present. the. of. along. the. to Mt･. in. distributed. of. of. angles･. of the. relations river-bed. and. generallyfrom. high. Mitumine. westwards. E-W,. and. kind. a. represents. NE-SW. Mt･. format.ion. res･ult that. at. northwest. lines,. from. shifted. the. area. above. the. lir]e running. present. with. structural. water-house. the. the. the. along. extensively. the. seen. gently. is the. line. this line. of. dislocation. important. the. that. prove. a. fault. lithological and. the. formation. be. to. seems. from. separated. from. line. a. along. assumed. structural. Koyasu,. the south-. Susugaya. the. Oyama-mati. to. subOtiai,. Hadano-si. Tbe in the. total vicinity. Division as. described. are. always. :. the. The. present. below. (Table. 2,200m.. to. in the. type. locality,. and. to. 900m･. formation. 1),. be. can. subdivided. the. stratigraphic. laterally. and. vertically･. both. and. into. relations. three among. members, the three. Volcanic･breccia. locality. Nakatu-gawa. attains. of Oyoma-mati.. gradual. Nunokawa. TyPe. thickness. :. 'The near. member the. entrance. is typically of the. developed Nuno-kawa.. along. the. river-bed. of.

(20) 76. K.. Lithic a. layer. thick. lava. are. and. also. The and. closely. phyre. of the. with. highly. monly. tlnged. with. mostly. with. purple,. of. calcite. and. fragments.. the. of. and. vertically,. porphyritic. In. base. and. blocks. are. amygdules the. rockboth. of rock-fragments. lapilli-tuff, both. or. found. the. purplish. basalt. of. as. en-. colourabout inclusion.. an. rocks.. whole. present. the. of. of yellowishfine-tuft,. kind. the. west. dark. of. breccia. this. throughout type,. the. in. 250m.. about. commonly. A. member. Hondani. river-bed. of. the. Nakatu-gawa. be. 930m.. N-S. nearly. strikes. and. the. alternations. its gradual. tuff, and. best. is. transition. Siomizu-bridge.. of the. north. lapilli- and. of. It is. in thickness. locality,. type. the. into. grades. the. Besides 1owlng. member to. to. estimated. this. of. belonging. in the. the. present. is. member. distributed. in the. foト. distributed. in. areas:. The. a) this. area. best. develops. breccia. are. composition A. few且ows. Nuno-kuwa. another. to. the. flow at. a. those. southern. of. blocky. point,. 350. fine-tuff, with. lava. Fudakake. the. similar of. associated. of blocky. near. very part. also. of. of. m.. south. volcanic. the. its entrance. locality. lapilli-tuff. or. the. where. type. the. of. of. is. basic. breccia. the. at. bottom. of the features. their petrographical. suggesting. that. identical along. they. represent. lava-凸ows.. afore-mentioned. petrographically from. that. occur. and. locality, of. Nuno-kawa,. coarse-tuff,. augite-basalt. type. extension lava. the. member. the. of with. water-house,. of the. present. course. identical. petrographically layers. The. lower. the. along. Thin. exposed.. of Fudakake:. area. northern. well. volcanic. occurs. matrix. the. com-. 50oE.. to. coarse-tuft. a. and. tuft-breccia. at. consist. augite-basalt.. develop. amygdules. The. are. and. is occasionally. Distribution:. seen. into. is. matrix. Veinlets. density. and. of basic. lapillis and. grey.. both. located. are. Karasawa-gawa,. across,. dips. in. grading. block-lava. of the. altered. Chlorite. of grano-. composition.. of the. 5cm.. of andesite. matrix the. the. while or. in the grain-size often. horizons.. breccias. common. actions;. brown,. common. very. of blocky. blocks. few. a. their. with. colors,. reddish. are. also vary. The月.ows. ed,. dark-green,. of. flows. in its upper. Also. hydrothermal. dark･green. or. prebnite. same. trance. green. They. horizontally. by. of. blocks.. together. affected. mostly. intercaration. Two. of lapillis and. former.. lapillis and. consists. occasional. layer,. same. largely. of the. breccias,. an. composition.. the. composed. these. volcanic. are. coarse-tuff,. are. locality,. type. with. same. with. dominance. mlngled. All. the. associated. the. with. are. breccias. volcanic. breccias. in the. member,. coarse-tuffof. volcanic. basalt. basic. of. alteredfine･. This. :. character. MIEAMI. with the. the. above. Nuno-kawa.. Also lava.

(21) Geological. Tbe. present. NE-SW. of. This. faults. by. mainly. basic. fine-, and. basalt few. of. steeply. The. western. in this. part. represents. exposed. in. branches. of the. bulk. of. the. type. locality.. this. southeast,. side. of. Mt.. Here, but. Angular lapillis. N6-. of. by. of of. the. fossils. a. mixture between. faults. of the. trending. distributed. member. its distribution,. breccia. the. from and. mudstone and. eastern. lapilli-tuft make. and. in composition. andesite. is well. and. N7-Valleys,. cherト1ooking. blocks. a. of S4-Valley.. numerous. and. differ. slightly. and-. Sometimes. tbese･ fragments.. present. of. volcanic. blocks and. augite-andesite. of. overturned.. The. extension. rock･. those. as. same. of the gorge. by. lapilli･,. the. of. intercalated. are. sometimes. gorges. west. consists of. coarse-tuff.. with. cut. 6yama:. southern. member,. with. member. the. member. the. of altered. bottom. is. to. Nuno-kawa.. the. in the. to the. features. almost. andesite. or. type. Of Fuda-. turned. coarse-tuffcharacterized. dips. of. are. mingled. basalt. this. bottom. the. acidic. in the. that. intercalations The. blocks. are. 77. faults. margln. present. of epidotized. exposed. the. the. breccia. matrix. tuft and, breccia. c). mixed. a. to. are. I. mentioned.. composition.. lapjllis and. area,. present. and. subordinate. volcanic. slightly. volcanic. the. NE-SW,. are. the. of dacitic. the. of. with. Part. numerous. northern. lava一点ows. area,. same. within. layers. grains. In. the. in the. this. breccia. by. corresponds. already. In. area:. Mountainland,. disturbed. as. spilitic augite-basalt. of. Thin. SW,. to. Abundant. embedded. blocks. strata. NEr. volcanic. locality. are. elastic. its associated. constituting. type. trend. and. coarse-tuffof. fragments. general. is disturbed. fault-block. of. is highly. however,. from. Tanzawa. the. on. area. its. member. runnlng. The. b). the. but. trend, the. where. Studies. in this. member. direction,. locality. kake,. Petrographical. and. in. basalt. those. up. of. fine-tufE. various. pro-. portions. Fossils as. :. In. thin. sections,. found. in the. present. member. are. follows:. Nos.. Locality. Fosssils. Localities. 12. Globigerina. sp.. 13. Globigerina foraminifers. sp.,. Minoge. TyPe En3-Valley, Lithic. Minor. Mother. Rocks. River_side of the Nuno_ kawa north of Fudaka_ ke water_house. Yellowish colored desiticfine_tuft. River_side. Matrix. of. the. Saka_. izawa-gawa. an-. of basaltic lapilli-tuff. Volcanic･breccia locality:. This. northwest character. of :. member Minoge,. is. typically. developed. in. the. bottom. of. similar. to. Hadano-si.. Lithologically,. the. present. member. is very.

(22) 78. K.. just. mentioned. member,. interbedded. with. fine- and. the. The in the of. common. the. is always. two. of basic. the. volcanic. breccia.. the. common. development. Distribution. It. Minoge. Mt.. near. to. member in the. the. the. calcite. distributed Knl-. of. leading. road. in the. rocks, and. from. of Mi-. vicinity. Minoge. and,. chlorite.. Kn2-Valleys,. and. ln. especially. of the. of prebnite,. river-beds. on. oat. rocks,. decoloration. strong. amygdules. or. mountain. similar. outcrops. sidering. from. the. north. of. Fudakake. to. brown. coloured,. basalt. the found. also. in. petrograpbic to. seem. a. small. and. and. valley. represent. forming. the. part. Mt.. the. of. are. eJeCta. blocks. Quite. of Minoge.. eastern. in. observed. Sengen-yama.. northeast. the. is. nature-. subangular. view-points,. of. localities. horizons.. andesite,. of. stratigraphic a. proportion. containing. foot. southwestern. in these. petrological. stratigraphic. breccia. along. whose. although. volcanic. are. the. breccia. in different. and. foulld. member. of massive. reddish. breccias. locality,. localities. path. of this. volcanic. type. of the. exposures. purplish. feature. of massive. in different. canic. andesite lapilli-tuff. between. transition. in these. seen. is locally. lithologlCal. that. Small. the. and by. accompanied the. and. are. the. cause. of the. crops. also. predominance. similar. of. They. observed. common. varies. horizons,. basalt. of. Sankaku-yama.. The is the. being. coarse-tuff,. commonly. This. :. is well. and. breccia. volcanic. gradual.. Hydrothermalalterations. noge,. massive. breccias. abundant. in various. composition. of. coarse-tuff. comprises. matrix. same. largely. consistlng. breccia. volcanic. MIEAMI. Con-. all of extension. the. vol･. of. this. member. The. present rests. mation into. member conformably. Karasawa. the. its wings ness. Lithic. Ash. and. brownish different. while. forit grades. vertically. the. and. loom.. of inclination. angles. horizontal.. even. sometimes be. to. Karasawa-gawa. the. of. formation,. axis,. being. is estimated. The. in the. of. The. thick-. the. river-. locality.. type. is. member. developed. typically. along. Nakatu-gawa. In. character: thin. of. 25o,. and. N-S. nearly. to. part. Tu,ff. the. of. with 5o. locality:. TyPe. mostly. from. member. Karasawa. course. folded. raI】ge. this. of. horizontally. tuffboth. It is gently. basal. Hondani-gawa. the. on. alternations. lapilli making coloured, horizons.. andesite. dark. of the. up. Thus. type. the. locality,. fine-tuft. basalt, and. rocks. present. member. coarse-,. green,fine-,. pyroclastic and. the. are. although. coarse-tuffare. their. lapilli-tuff.. and. commonly. of purpli､sh. proportion. abundant. consists. in. varies the. upper. or. in.

(23) Geological horizon,. while. horizon.. Sometimes. is found. in. Petrographical. and. lapilli-tuff. the. or. rocks,. colour. of greenish. will. be. A. thin. zon,. described. lapillis and diorite,. blocks. the. The nant. type. rocks. It. tions.. of the. plane of. massive. and. the. b). of hornblende-quartzthese. have. whose. ejecta,. been. derived. of this. member. ､directly be. will. Besides. lower. of the. river-beds. (from. locality,. type. the. Krl-Valley. the. the. of the. course. to. Kr7-. the. often. is also. mudstone. or,. best. breccia. as. a. is the. into. conglometrate. be. propor-. bedding. the. ina. layer. thick. Karasawa-gawa. the. of. the. of. coarse-grained. to. found. junction. the. predomi-. in various. parallel. can. most. in the. breccia,. arranged. of which at. type. found. volcanic. patch. example exposed. mixed. grading. lapilli-tuffand. block,. the. the. Kr3-Valley. The. fault-block. coarse-. branches.. and. The. area:. in the. exposed its. and. fine-,. varlegated. a.reas:. branches. localities,. a. strata,. three. lapilli-tuft of. such as. hori-. map).. as. volcanic. is typically .gawa. celadonitization,. somewhat. distribution. in the. Cbert-like. occurs. mixed. upper-middle. with. mu･st. faulトblock:. eastern. these. composition.. pyroclastic. mixed. these. the. observed. mentioned in. that. of the. its. geological. above. or. Blocks. occasionally. following. area. and. rock. same. in the. is well. in the. valley. in the. and-basalt.. convenience,. northern. member. are. found. blackish,. purplish,. indicate. For. :. Karasawa-gawa. the. ash. by its peculiar. intense. the. the. mass.. described. a)) The present. across,. quartz-diorite. separately. of. is also. of augite･andesite. features. Distribution. to. latter. the. In these. with. lapilli-tufE of. lapil1. or. layer.. thin. mingled. from. its origin. breccia. volcanic. 7cm.. petrographical from. are. (coarse-tuffor. owes. essentially. about. dacite. mudstone. coarse-tuft. a. lower. later.. of. consisting. as. alternations. distinguished. which. dacitic. 79. I. the. brown-coloured. horizons,. dacite-tuffor. towards. amount. reddish. some. Part. Mountainland,. in. of. above. is clearly. blue. layer. In. proportions. former. the. and. patch. the of. various. type), as. between breccias. lapilli in. a. lapilli-tuft.. or. 1i･tuff is intercalated pyroclastic. or. Tanzawa. the. on. increase. to. tends. breccia. a. coarse-. Studies. river-beds ロere,. lapilli-tuff, and. present. of the. it consists is. distributed. member. course. mainly. of. of the. middle. interbedded. thick. a. thin. with. in this. area. Karasawaof. alternation. layers. of. volcanic. breccia. The breccia. lapilli-tuffis of. the. almost. cbert-looking. of. the. mixed is. mudstone. type.. The. frequent in. common. the. occurrence. above. of. pyroclastic. rocks. The river-bed. southwestern of the. Nuno-kawa. extension from. of. this. Fudakake. member to. the. is. well. northern. developed margin. in the of Moro-.

(24) 80. to,. K.. the. and. also. In. these. desitic. localities,. of basic. located. tic coarse-tuft. well. The. in. and. layer. light. contain reddish Tbe. present. the. along mainly tufE,. right. member. also. of. type. mixed. the. and. layers. are. of. tuft,. Mt.. being. black. between. these. valley. it consists lapilli-. coarse-tuff,. as. basaltic. to. lapilli-tuff. or. pyroclastic. or. Oyama-. incised. Here,. andesitic. shale,. commonly. to purplish. deeply. such. thin. a. of the. Oyama.. rocks, all. rocks. Mt... of. with. riber-beds. of the. of. pyroclasic. sandstone,. intercalated. also. path. sandy. the. bottom. member. coarse-tuft. in addition. sp_ are. northeast. pyroclastic. along. in the. ascending. of various. breccia,. These. is exposed. especially. side. and. basal-. of. Globigerina. of this. strata. andesitic丘ne-tuff,. of andesite.. Thin. positions,. of. breccias. of alternations volcanic. horizons.. beds. yield. Karasawa･gawa,. the. of. The. :. an-. of. intercalations. Thin. shale.. Nuno-kawa. of the. we11･bededfine-. some. its beanches,. and. of. breccias. green. coloured. gawa. largely. consist. lapilli-tuffin. of. the. alternations. occasional. and. fault-block. course. upper. well-bedded. sandstone. junction. of. of. lapilli-tuffwith. and. the. area. the. mostly. tufEaceous. at. southern. exposed. Oyama,. coarse-. breccia,. volcanic. of Zigoku-zawa.. gorge. it consists. basalticfine-,. to. c). of the. river-bed. MIKAM:I. com-. the. of. in different. rocks. borizons. Tbick gawa,. the the. strata. north. rocks, They. is 1,000m. Fossils. Locality. makes. it di氏cult. :. nearly in the. In thin. Nos. 14. various. Strong. constitutes. trend. the. the. to. bulk. to. type. sections,. Junction. Globigerina Orubulina. of the. sp., sp.. of. of the. nature. present. member.. formation,. latter.. in the. the. of. and. The. total. Minor. Nuno-. SakaizaFudakake. southwest. of M7-Val of. are. member I. the. River-side ley, Mt.. 17. of the. Localities. sp.. sp.,. the. of. alternation true. Karasawa･gawa. that. wa-gawa,. 16. lapilli-tuft. of. bydrothermal. the fossils found. Ditto. Globige'rina foraminifers. layer. Hinata-. of the. and thick-. locality.. Fossils Globigerina. thin. horizon. of the. corresponds. river-bed. understand. upper. kawa. 15. a. borizons.. represent. the. along with. probably. member. exposed. associated. however,. its general ness. in. type. The. lapilli-tu任are. Oyama-mati,. of. mixed. strata.. of. Mother Altered. follows:. as. Rocks. basa】tic. coarse-tu庁 Dark. green. andesitic. crystal-vitricfine-tuff. Oyama Nizyu-no-. Near. the. taki,. Oyama･mati. Tuffaceous andesitic lapilli-tu牙. mudstone, and. coarse.. Tuffaceous. Ditto. andesitic. and. mudstone, andesitic. coarse-tuff. 18. Globigerina. sp.. Below. the. Oyama-hati. Fud6-d6,. Andesitic fine -tuft. crystal-vitric.

(25) Geological. Locality. Petrographical. and. Ditto. Minor. foraminifers. i. Naof the Miyagase. River_side. Part. Mountainland,. Localities. katu-gawa, 20. Tanzawa. the. on. I. Fossils. Nos･【 19. Studies. Mother. I. 81. Rocks. Altered. andesitic coarse-tuff Dark. Ditto. green. andesitic. 丘ne-tuff Globigerina. 21. River･side. sp.. Kr8-. the. of. Dark. 22. Ditto. River-side. Kr7-. of the. Black. Susugaya. of this. region. in the The. From. are. The. by. is extensively. distributed. from. the. the. Otiai,. of. total. 6sawa. the. two. the. general. SE,. and. the. the. western. in the In the. present. sediments.. the. three､formaThese. three. into the upper. one.. north.. area. developed. along. thick. accumulation. This. :. part. the. hilly. land. is intermediately of Susllgaya. closely. and. westward. northeastern. hilly. formation. seems. the. to. of. exhibit. are. cut. the a. is NW-. part. faults. which. dislocation,. Hadano. basin, fold. and. it is disturbed. by. formation.. area. Susugaya. eastern. of this. synclinal. the. over. (Fig. 1).. altbougb. afore-mentioned. shifting land. basin. northeast,. relation. vertically.. including. in the. ■the strata the. and. of. hori･ dacite-. stratigraphical. region Hadano. lower. the. the. in. base. Fud∂ziri. is distributed. distributed. to. to. the. of. Where. in relation. the. former,. at the. towards into. laterally. of the present. of the formation. trend. in amo■unt. formation. The. ones.. developing. (Table I), and. transitional. eastern. basic. mostly. both. a. of. be subdivided. can. tufE members. the. dip. typically. and. decreases. formation. is always. overturning the. into. in the. mostly. dowowards,. latter. southeastern. The. is. intermediate. to. distribution. from. formed. the. present. GeograPhical. been. normal. grading. 2,000m.. It consists. :. progressively. the. to. each. afore･mentioned. (Table I).. orde､r. formation. Division. and. while. the. extending. and. classi丘ed. another, over. the. southwest.. Nakatu-gawa.. increases. between. be. can. to be. present. in addition. formation,. 6sawa. The. :. character tuffs. tuffand. npon. is estimated. the. of. Thus. it. in the. from. D6si-gawa. the. of. basin. pyroclastics. in descending. one. drainage. the. parts. southwestern. Formation. river-course. general,. acidic. view. 6sawa. and. conformably. locality. acidic. of. and. distinguishable. of. point. thickness. Lithic. is clearly. eastern. Ⅲadano. of the. margin. predominance. Zike. superposed. zon.. eastern. lithological. the. TyPe. this. the. subgroup. Ⅰ) Osawa. of. occupying. present. subgroups■. tions. Subgroup. to. north. andesitic丘ne_. Subgroup. Susu甲ya. The. andesitic. tuff. valley. C.. green. 負ne-tuff. valley. on. with. in have. res山ting. the. other. the. axis. band′, of NE･.

(26) 82. K.. SW. direction,. 80o,. but. the. and. its detailed. angle. MIEAn4I. inclination. of. is not. structure. both. of. known. wings. because. from. varies. of the. 50o. to. of proper. absence. exposures. seen. in Fig.. zone. (the. Makime-Hirado. local. overturnlng. Of this. The. total. As fault. a. the. the. along. Ⅰ,the northwestern. thickness. in the. eastward. type. locality,. line),resulting. is cut. by. shifting. and. formation. in. 1,200m.. exceeds. river-course. formation. of this. extension. of the. Yude･gawa.. type. locality. the. 2,200m.. and. Fud6ziriDacite･tdr locality:. TyPe. is developed. It also. gawa.. Lithic. The. ternations. coarse-. offine-,. andesiticfine-to. bulk. the. commonly. of bluish common. Distribution. Oyama. This. :. The is best dip. in. a. gradual. lS. Steeply. Southwards, the. dip. and. in. part. Mt.. sporadically. scattered. ridge. directed. basalt. are. along. mingled. horizons.. 6sawa. Qf the. part runs. which. also. are. for: from. northwards. to. member and. here. Karasawa-gawa. the. the. formation. is nearly. trend. N 30o,W,. and. the. being. Monomi-Pass. Further. part. of≠this. of. this member. change. trending this. overturned. a. to. faults. numerous. the. of. begins. trend. member. to. N-S. direction. in. NE-SW. and. its strike･ into. turns. member at. south,. is shifted. direction,. the. southwestern. westwards. by. the. fault.. southern of. N40oW,. and. member. grades. 6sawa. tuft member. The. They. northeast.. by. Mitumine,. afore-mentioned. river-course. the. vicinity. direction,. The. of this. steeper. NEISW of. to. a. alternAtions.. celadonitization. regularly. basal. of. pyroclastics.. in different. the. along. area. or,. and. and. occupying. locality,. type. andesite. these. al-. layers. wide.. transition. however,. becomes the. lkm.. of. are. and. coarse-tuft,. localities. member in the. belt. in the. seen. breccias. in different. is distributed. nation. the. few. breccias. these. with. Mt.. A. rhythmic Thin. strong. of the dacitic. green. of. composition.. by. in colour,. green. largely. between. characterized. rock-fragments. of dark. matrix. strati丘cation.. dacite. bluish. or. Nakatu･. of the. river-bed. consists. intercalated. also. or. of the. member. lapilli-tuft of dacitic. and. of dacite-tuft. constitute. the. present. coarse-tuffare. Breccias. in their. The. :. character. the. Monomi-Pass.. the. near. is along. the. thickness. extension Yude-gawa. the dip. laterally. of. into the. near. the. Fud6ziri. near. 30o. nearly. to. the. Zy6hatugan-zi member. in the the. where. northeast.. alternations. present. is observed. It. seems. of andesitic temple, is 325m.. area. general likely. along trend that. the is this. tO. the. river-Side. of. tuffbelonglng. Takabeya-mura. along. the.

(27) Geological. Nakatu-gawa,. the. In thin. follows Locality. 800. and. Fossils: as. Petrograpbical. and. Studies. m.. fossils. the. sections,. Mountainland,. Part. 83. I. MonomトPass.. the. near. Tanzawa. the. on. found. in. the. present. are. member. :. Fossils. Nos.. 23. Minor. 24. Localities. foraminifers. Globigerina. katu･gawa,. Na_ of the Miyagase. River-side. of the. River-side. sp.. Mother. Rocks dacitic. Bluish grey fine_tuff. Kr5-. Ditto. Kr9-. Ditto. valley 25. Ditto. River-bed. the. of. valley. Osawa. Tuff locality. TyPe. Lithic ternation in or. of丘ne-tuff,. coarse-grained. dacitic. to. changed horizon. middle. of the. もreccias. are. blocky. the. to. similar. that. from. lava. of. (type Ve). andesite. breccia,. volcanic. Disiribution in the. and. an. these 血e-. in. and. breccia. or. of the while. in the. predominance. i□ the. lower-most. others. of. partly. formation,. underlying. its. breccias are. volcanic. occasional pyroclastic. The. dykes. basalt. of. (type e). These. member. as. of view,. locality,. the to. the. of. will. layer found. are. are. rocks be. present. intercalation. map,. Fig.. specially. described. later.. is distribut-. member. coarse-tuffwhich. are. (fromナthe largely. consists. andesitic. derived. the. along. Yl-Valley. riverto. the. 1).. pyroclasitic. included. are. observed. branches. member. of. are. exposures. western. present. andesitic. rocks. best. its. and. geological. part,. of dacitic. type. is embedded. few. a. also. the. part:. Yude-gawa. in the this. to. the above. areas:. eastern. of the. Y4-Valley. Besides. :. following. The. a). In. the. the. Two. between. breccias. al-. to andesitic. subangular. These. of the. each. dacitic. in colour,. found. of. thick. a. of. volcanic.breccia.. grey. composition,. horizon the upper present of the ･in from the petrological point noticeable. tions. river-side. of augite-dacite.. A. beds. from. of. greenish. dacite. In. differs. mainly. intercalated. commonly. sometimes. very one. layers also. almost. celadonite.. is. upper. is. there. dacite-tuft,. are. shale. tuft. 1t COnSists. thin. with. tuffor. rock-type. green. wholly. ed. the. along. lapilli-tuffranging. coarse-tuffand. of sandy. The. ･alternation.. of. developed. locality,. the･type. alld is associated. layers. three. bluish. In. character:. composition,. that. is typically. member. Nakatu-gawa.. the. of. This. :. rocks. from. grains,. of丘ne. lapilli-tu庁and. gravels. strata. lying. of. alter甲-. associated. volcanic. breccias. and the. of rbytbmic. with. breccia.. various. conformably. kinds. In of. under.

(28) K.. 84. Besides,. tuft.. each. in the. shale. the. The. b) ber. above. to. member. Oneyama,. kub｡. Zenba. is. feature. is the by. characterized. and/or dacite-tuff,. a. the. are. augite-dacite by. affected. iron. Besides fine- and. these. The. of Kuma-. and. K6ba一三an,. two. bluish. thin. a. dis-. colour. duel. of. spherulitic. They. highly￣. are. reddish. coloured,. breccia･. a. of dark. green. pyroclastic. above. whicll. clearly. green. Also. Itsp. augite-dacite. are. breccias. alternation. the. with. as. breccia. rocks. fragments･. them,. among. locality･. type. basalt, and,. last. found'. member. volcanic. of celadonitization･. associated. Mt.. and. valleys,.. vicinity. the. coloured. above. rocks,. pyroclostic. localities･. small. present. of. unusually. the. is found. coarse-tuffis. that. purplish. instead. oxidation,. the. the. of. of andesite,. their. with. mlngled. mndstone. cherト1ooking. from. proportions.. Sometimes,. celadonitization.. the. of. of lapi11i･tufE and. by. men--. of Ozakiyato. Zenba-Pass,. lithofacies. the. of fragments. others. present. Ⅲadano-si･. predominance. mixture. present. following. vicinity. (3). and. of the. The. river-beds. (4) the. and. different. quite. in various. from. tinguishable. town,. that. the. tuft. sandy. nature. the. the. Isehara-mati,. temple,. here. localities. these. in. (2). its surroundings,. noticed. in. (Ⅰ)in. :. of. basin:. exposed. southwest. sable. Hadano. of the. is separably. Mansy61Zi. and be. distinctive. to. land. Isehara･mati,. Gongenyama It must. are. hilly. to. in the. the transitional. formation.. part. northeast. of the. and. Mt.. in. in this. Hibita,. northwest. indicates. layer. thin. a. of. Zike. northeastern. from. occurrence. alternations. overlying. distributed. arranged. frequent. a. MIEA班I. andestic in. rocks. smau. amounts.. The. c). the. along the. following. along. the. mura,. (3). of the. D8si･gawa. terized. the. localities. :. alternations. dominant. The. mation. Fossils. :. total In. to. dacitic. of. of Hayado,. (4). Tukui-mati, and. (5)along. Åome-bridge. in the. in these green. localities. along. the. river-side二. the mountain. path. town･. cbarac-I. commonly. and-. coloured,丘ne-. Sandstone. composition.. (2),. Kiyokawa-. same. is. brownish. or. Miyagase,. Oi-sawa,. the. of. in. observed. and. are. shale. pro･. northwestwards･ trend. general. the. distributed. member. of andesitic. gressively. from. northwestwardsv is well. horizon. southwest. Tukui-mati,. Aonohara,. rhythmic. coarse-tuffs. Hirado,. the. present血ember. river･bed. Hayado-gawa,. Sagamiko-mati,. by. localities:. of. near. present. The. vicinity. in the. in the. (1) the. the. its upper. locality,. type. of. river-bed. tb Sinobara, The. from. strike. Tracing. part:. northeastern. of this. thin. thickness sections,. member is about minわr. nearly 850m.. with. coincides type. in the. foraminifers. are. that. the. of. for-. locality.. found. in the. followlng.