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<br />0"', 7", <br />v " <br /> <br />granite predominalLng. In the grologK past. theo;e weh <br />ha~'e been sculpwred by ice Jnd W31er to produ.:e the <br />rugged peaks and steqHlded valley~ which (orm Ihe <br />alpine tupography seen today. ErnslOll Ie-nd!i to he ,low <br />in these areas and the mountain slreams do nOI generally <br />carry largi:' .l[lloads. <br />A [Jrgt' pUr1iUIl uf the '.lisSlluri BJ!iJll is composed tlf <br />plains and praIries. These area, are underlain by ..edi. <br />menial}' rock formations ..:omlslinj!: predOTll1ll3ntly of <br />clays. ~Jles. ,ills. s.Jnds. and sandstones. SUdl a/CilS <br />erode mud] more readily th;m 111(' older and more COil' <br />solidated HKks (J1 the mountaill\lU~ area.... Luge ~~.lluns <br />art' covered by recenl deposits of ull~'unrolidalcd ~daClal <br />Ill!. sand. gravel, silts. and days lefl hl'hind by the con. <br />tinental glaciers and the lon~.term eHe.:ls of wind and <br />water. <br />Most 01 lht' soils in the basin havl' developed undt'r a <br />grass co~'er \lajor ex.;eptions all' the soib of the muun. <br />tainous areas wherl' forests haw been the predominant <br />~'eg...tallon. O.......r lite b:J.SIn. m:J.ny kinds of suils ;m~ found <br />with wide v:J.rt:J.lioIlS in profile .:halad...rbtll's :J.nd use <br />capabill!les_ Zonal soils lKCUp)ing variuus palls of the <br />baslll llI.:lude: the BrunI/ern suils of eastern h:Jns;Js and <br />"ebrash. Illwa. MIS-SOUr!. \linm'sllla. :J.nd ...xlreml:' south. <br />eastern South O;Jkola; the Cherno/em soils In :J. lone <br />that exl...nds from e;Jstern Sorlh and Soulh D;Jkota <br />through central Sebrasb and h:Jl1sas: the Chestnut soil> <br />III northern Montana. western "IHtll <lnu Soulh Lhkuta <br />:J.nd \ebIJsb. and northweslern Kalls.as: the BlOwn SOLis <br />in eastern \lontana and Wyomlllg and nOrlhcas1ern <br />Colorado; thl' Si...rolern soils 11\ thl' intern1l.luntJin basin <br />and in the hIgh dry plateaus in northwestern Wyoming: <br />and th(" Pnd/olrc soils in the fl.rl'skd areas uf lhe Rod,~ <br />~llllllllaills III western ~Ionlalla and Colorado and lhe <br />Olark Pl,tteaus 1ll Mis.~Ollfi <br /> <br />Physical Divisions <br /> <br />Thlce distinguishable major phy~ical dlnmllls dt;!r~,- <br />teriLe the basin :is Jelill("al("d in fIgure -' TIll' Rlll'ky <br />~Iounlam System oc.:upies II per.:ent of the basin. the <br />Interior PlainS Sf:> per.:clIl, and the Interior Iltghl:l.llds <br />Ihree p("r.:en1. <br />The Rn.:k~ ~luuntain SyslCm ':(lTlSISIS of th... muun. <br />tainous areas that form the western boundary of the <br />watershed in ~h)ntana. Wyommg. and Colorado. ThIS <br />area is .;hJla~.lelj/("d b) alternaung promlllent muuntam <br />ranges. inlern10Unlalll basins. and relatively wide \'al1cys. <br />Elevatiuns range from ab\lUt ~.sOO feel to nll)re than <br />I~.OOO feel abo\t' S("a level. ~lin~lr tributaries hav.c slCep <br />gradtents. and channeb generally at... "V".shaped. The <br />streams commonly !low thwugh stt't'p .:anyuns befure <br />they rCJ.:h the llKlre l("veltop',)gTaphy 01 the plains where <br />slrean1gradicnlSles~n <br />Pllf!l\lnS of four provlll.:e~ of the Ro.:ky ~h)untJin <br />System are wnhlll lh(" baSlll. Th("~e provin..-es are the <br /> <br />Sorthern Ro.:ky \Il1ulltJins. \liddle Rl'ICky ~lounlaIllS. <br />Wyoming Ihsln. ~nd Southern Ro.:ky \Iountains. The <br />Wyoming Ba~l!1 province inlerruplS the .:ontiIlUil} of the <br />R,)(ky ~lountain System ThiS ba~in extends aaoss the <br />~lou!1lalll Syslem hetv,een the ~Ilddle Rocky \ll1ulltains <br />and South("rI\ Ro(ky ~hlunlalns prllvlll.:es. <br />In lhl' Wyomll1g Basin the Conlinental Divide has no <br />distm.::t wl1Ileaing crest. Here lies lhe Greal Divide Basin <br />from whlrh nu drainage rea.:hes lhe sea. 111(" term "Great <br />DIvide Baslll" is used d1lel1) in a hydrographk sense for <br />the alea of internal drainage of abuul ~.160 square miles <br />1Il ('xtent luble I J. The noor of the Wyoming Basin is <br />charJ,;[eristicall~ ~imilar to a plateau and is continuous <br />.....lth Ihe Great Plaim through broad of't'nings between <br />muuntJlll r.Jnge~. The ba~in mdudes extensive areas of <br />plaleau parks suppmtll1g mixed grasses and shrubs. This <br />basin IS used mainl} fl'r fall. winler. and ~prtng graling. <br />Three Ro~'ky ~"luntain proVlllC~'S indude cXlensi\'e <br />areJ~ of coniferous forests and 1Illermingkd mountain <br />palks suppl1rling mixed grass("s and shrubs. There are a <br />numhel uf lIllClIlWUlllaln vallcys belwet'1l the mountain <br />mass("s. TIlese area~:J.r(' used m.Jinl~ fur paling. but some <br />ha~'e heen de\'cloped mtll rl.-h farm lands. TIle Ro..:ky <br />~1,lUlllalll ponion of [h... basin is a primary snun.'c of <br />water for the Missourr River and mallY of 1IS tributaries. <br /> <br /> <br />-':/ <br /> <br />.11l' <br /> <br />~ <br /> <br />'" .~ <br />..... . <br />. .\,i;.-. <br />~~~~~ .- <br /> <br />- <br />.... .- <br /> <br />J.... <br />J" <br /> <br />Rocky \Iounl:lim <br /> <br />) <br />