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Show Jt()(' l\.\' ~IOtJN'I'Aii'f , C'ENEHY. t It Occu11i R an :u·pa abont l 00 m ih·R in l!·n~t h and 50 in t>ltR . . f f ht'('<Ldth. Nt>ar Jn.tilude 4·Ht0 ancl longiluck 102° tlte lin • o' ra ·tnn1 RPl'liH:l to hnH' partially dit•d out toward the south and R< nttltt>a t, and lo havP madt> a gmdnal tlt>Xttre around to tltu wt•Ht, tltP wholt> t·atw ' soon l osing its graniloi<l chat·adPr and l>N:oming pntit·ply <·ompos('d ol' lli (H'P modern t'I'Upti Vl' I'Ocks. Tit • t•rupti Vl' ]lOrtion eonlintll'S Wl' ·hvanl nnlil it j oin th> Wind Rin•r· mngl', nPar tltl' sou r·<·t•s .o f' \\ intl Hin•t·. A t the t<Oullwrn !'11<1 of' llw Big Hom l\1 on ntatns w • can tm 'P a sin "'!!' low anti -clinal aeross tho pmiril' l'Ollll!'('ting t hPHl' tn01111tain · will, thP Laramie mngt• ul tll t' ]~Pd Buttt•!-i, on thP NorLh PlaLtt•. \\' L' l'artht•r know, hy tlu• position of t ltP HP(li tnent:ll'y 1w<1s nphmv( d al ong th(• III O tllltain ~>, that Llwst• 111011n1aim; n.l::;o f'onn a t'Ol llt('e( ion with thl' Wind River rangt> by the gradual II ·xure wt•slwanl of' th • Pruptin:) ro\'ks. Tht> ·entral portion of' tlu•.·p nwuntains is al so ·ompo,;ed of' grrtllilt• aml granitoid l'lH'ks, with tiH' Sllll1P Sl'ril'H Of f'o •::; iJif<.' I'011S l'onua.tion ·. in ·linin <> at rariouH angl(•s front t•ach ::;itlt• of' tlte uxi · of' p]•ration, a' is se'll around thP Bla('k llill ,.; and along thP Lmamit• lll onnlnins. 'om<' of 1111' mon· lofty pt·akH an· f'rotn 8,000 to J2,000 l't>l't above llll' S<•a, an<l are corPrNI with l ll'I'}Wtun.l HJlO\\'. \\'p t it ink that tltl' ~·v idL' Il C! i ' quilt• ('OIH'fm;in• that, liJl (O tht• tint (' of tht• lli'GlltllUlation ot' a htl'f!;l' portion or UH· LigJti( t> 'l't·rtiary bt•<ls, all t lte '(' l'ot·ntations, front the 'ilurian Lo th t> trur Lignit(• ,.;lmla, itwlu si v<', wPr · in a horizontal position, PXIPrHling rontiJtUously ov(•r Lht• wl10l arl'a ocntpi('(l by till' mouutaim;; hnt af\ t hPy '''l'n' HI owly l'l <' l':ttl' 1, th<• l'l'nlml portions wPrl' J't•m ovt•tl l1y tit' t•rosin• al'lion of' wa.lt•t·. 'l'h t' t•ruplivP vorLion which unit 'l:i Uti' Big lfom l':lllg(' witlt liH· \\' intl H.ir l'r ]IJountainH is I'Xct• dingly pirtnn•sqw·, presentilll-( tl11• appl'al'an<"t' of a ''onnP<·tetl eries of btvaltic com•s, hut i ::; so t·uggl'tl and inaccL'::>s ihl t·, ih:tl OVl'll the lJt'l'Severing tl'a})lJl'l'S ltal'l' lll'\' Pl' bt•t•lf a bit• [O }Wllt•trate il i 11 thL•it· It u nti ng cxplorn.tiont>. . Lik' the Bla ·k Hills, lhP Hig Hom rangP doPR nol givP ri e to any tntpot'lant sub-hy hogntpltieal bn.sin . '!'Itt> largpsl stn•am in this n·gion, and one which gives mune lo th<' mounlaittH, ri .l'H in Llw \iVind Hivt'l' t·;tngt•, pas e tltrourrh the Bi~r Hom Mount.."l.ins, aud unit1• · with tit Y •llow 'ton about 70 mill' to tlt1• JH>rtlnnml. BPf'ot·t• J't•acltiJlg tlw mon~tains it tak ,,· tht> name of \Vintl H.irpt·, and a::;sunti'S tit· mU1ll:' of Btg ll01·n after em,,. in "' front tlwm. Thi rangl', howevN, constitute· 0 E ClltA !'Ill(' A L. quite an irnportant fh•cl 'l' to th Yell owHtonn. Powtl r Rivpr·, wl1ielt riHo in tltir; rang • by nuntOI'OliS bmnt'ht>s, drains a la.J'O'C at·ea, mo.·tly Li"'nite 'l't•t·tiat·y, aud }JOur n. cmtskl<"rabl <' volumt• or watt•t· into tlu• Ycll owl:!lono, n •at· l o n ~ itude 1051° and lat itntl• 4.01°. Tongu • River i · th <' next n!ost important Rlrt•am, whi<'h, th ough not draining o "'n•at a.n rtt'(':t as Powtll'r Ri ver, mpti s into LitH Ydlow -ton • a ntu ·h hu·~rpr volumP of waLPr. TJJC Mt•dit·in <' Bow and 'wedwatet· l\fonntains appear to lw of the sam ' ·h:uadt·t·, for lit • lll O::;t part· 1)ut on tit • ·a t sidt• of tlte 'w •etwaLt•1· H.ivnr, tltl' cv id l'll<'P of ign •ou · a('(ion is shown 011 a lat·rro scalP. '['ltt• anl' i ·n t vokanic ntall'l'ial would st·<· tn to hav<· h<•t•n d cvated to a gr·cat ht'ig lt t in l)nt a partially fluid COII(lilion, and th t•n to ltavt' ~r r·a<Luall y I'OOietl, aflh:li ng to a g t·<·aLcr ot· l eH · PXt(•nt the ro::;::;ilif<•t·ou stmta in contact. N<•ar tll<\,iundion of tit Popo Agi<' with \Yind Hi vo r, wl' <·omt• in full vi<"w of' tht• \\' ind Hivt• t· Mountain:;, wltit'lt f'ot·m lit <' dividing c·t"<'HI of tit • eontint•nt, the ·( reams 0 11 tltn orw sitk fl owi ng into tltP Atlantie, :wcl lltos on thl' olht• t· inlo t IH• Pac·i fi c. Tlti · mngl' i;; a.! so cont})(lR(•d, to a large l'X1C'Ilt, Of' I'('() aJI(J gray fpJcl ::;patltie crranif<•, with lite fo::;::;iJil'ct-oUH rot·k ::; in\'lining high upon iLs sid H. Afkt· pa;;Hing tit,. RO UI'Ct's of \VirHL H.ivl'r, tl1P mountain::; appP:u to lH• eonlpost•tl t• ntit·c> ly of' t•nrptiv' I'OCkH. EvPII nho Tht'('(' '!'don s, wlti c·h rai ::;o t.IH·it· Slllllllti t::; 11 ,000 ft•<•t :tbO I' I' lito OCt'an lt'Vl'l, :ll'(! fOI'IIII'd or Vl' l',Y ('0111pact basal fi t: I'<H'k. ']'It \\'a;;aleh and G t·r•en Hil'l' t' ntng<'H, w]t Pf't~ wo ohHt•t·v<·d tltt•nt, have tho samp ig tu•ouH origin, and tlt <• ntountains all a.long tht• HOIII'('(•s of till' di(l' rt'nL hmnciP of' the 'o lu111hia (•x hibi t tht'Hl' t·o ·k!-l in tl1l'il' rnll for<'<'. ln Pit·IT<'';; Hole .JaeJ · ·on' !:' lloll', and othl' t' valley· ::;ntTountlt•d by uphpaved ridgPS, tltp.· '• ancil'nt I'Ok:tnil' l'<ll'k sl'<'IH to hal'<' bt•Pn potll't'CL ovi'J' the country, and to havu ·oolt·d in layt•t·s, givitw lo l'a -t thkknp::;;;e of th • roeks lhe appl'amnc·t• of' st mti fit•d lwdR. 'l'hl' ntountain::; about. tit ' ·o ut·ct· of LltP Jvlissouri and Yell owstone Riven; aro of' •t·upt.iv ot·igin , and in Lhl' valll'y or tit(' Matli ~:;o n l'o l'l~ of t it ' Mi ·so uri are vt• rti eal walls of (.11 'Hl aneit>nL vo l<·ani · ro ·ks 1,000 to t ,GOO ~ -l't in it (• igltt, xltihitirw lht• appt•amnel' of :;tmtilit•<l tlt•positi:l, dipping at a. C'onsid •mble angl •. As w<• 11a H down the Madi ·on we lin<l ·ome bedH of' f'eld ·paLlti · rork , and mien. and ·lay ·Intt>::> 1 t•m•ath till' l' t'uptivo layN , dippitw at the sum angle. Af' •r pa inn' the divid 3 |