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<br />Figure 2. let!: The WIllcox Playa. Arizona. was flooded to form this broad. shallow
<br />lake following extenSive rainfall In 1983 (phOlO by A Todd) In even welter times. the
<br />closed Willcox baSin was occupied by pluvial Lake Cochise. Right: In penOds of
<br />drought, eKlenSlve closed.basln Jakes quickly dry mto a sea of sail and sand, such as
<br />In lhls playa In Death Valley. California. 1972.
<br />
<br />inr('r,I(tlOns amlln.c pl.nes In rht: t;Hth's cruse.
<br />Opening. ur" the Gulf of Cddorni" \\".~ pHI of d11~
<br />teUOnl( r,lUt"rn InbnJ. e.ls{.tu-We~[ s[ft"h:hln.~ of [hI:"
<br />l~wJ surluc: In ,\[lO(el1e (........20 [() 5.0 mdllOn n:a.rs
<br />.\~ll) !factured an .lnCle11l .dmost.h:vd !I:rr..Lln lllrn
<br />nonnwes(.soutneas[.rrt:ndln.c mounUlns and p;H;!lId
<br />,-,tllen.
<br />Rjven wuh ].If~e entlug.n w.ltt'rsheJ~ ellt dt.ep
<br />cmyoos dH(lU~h rlsln).: plateaus ;\OJ moulluin
<br />r.IOl:ks, Others wert: Jlverrt,j ~y upbfun,e lllllunUlll
<br />r.lng('s. HU~t' Jakes. represented wdJY by dry pl.\~'.ls
<br />.lnJ .. few remnants ..u(h .IS Gre.1f S.llt Like, Wtrt
<br />(,lfmed In dused b;lSIllS. Their warer~ rOM' .-Ind fdl.
<br />IIJhn~ l(lUllWt,d by eplsodi( dryin.l', rdiJlin,c., ;\Od
<br />spdlill).: ()Ver rhelr rims r\l connelr With mher l;lkt's,
<br />flHrs, or rhe se.\ In Pbmt'ne .lnJ Plt'JS[{H:Clll;> (').0 [(l
<br />1'\.02.0 and after 1'\.o.?O mdlllln yeJ.f.. ;It:O, H:spc(tl\ely'l.
<br />mounf.lin FIJ(ler'i came ,Illd went on tht. hl,>::ht'SI
<br />peaks. rellt'dlnt: (older. ....t.t[t.r (OndltllJnS than today
<br />and ('orrespondln..: with .1Irernaung pulst's at
<br />(ontmenral ,cl.lu.umn III the north
<br />Plw,PlelStil(em: uplift Ilf the SIt:rr,1 ~t'\JJ.I Jnd
<br />Other mlluntJlll r.\nFes .If C.lhlorlll;l rt"sultnl In
<br />permalll.:m chm.ltl( ch.lnge when the\" rose high
<br />enouf:h to Illtcr..ept rhe e.lstwJ.fJ 110\\' of P.IClric
<br />moisture, \\',Her r";llbn,c. on their \\Tstern slure.. r.1n
<br />h,lck to tht. sca, ;lll.lunly Jr~' JJr p.lssed d(lwn~]opt.
<br />to the InbnJ bJSlns ,llld plateJus, Pt"rslstellt .lTll.llry
<br />\\;1., thus assured. Fn'll Jncr ((llllllrwlls \\Trt.
<br />Induced in the Sll[l(lr;ln Desert b~' hlrm;ICILln Ilf
<br />pt:'rm.lncm (dh I)! hJ.eh ;lrmlhpheflt prbSlif(', (.1UseJ
<br />r.y desCf:m III' hl.ch-.dnruJe .lIr ro rht:' c.Lfth.s SUrra(!.'
<br />
<br />Tht. dt.'s(enJJOF an [;Ilks hum,JJ[~. bec.IUSt' of IlS
<br />Ofl~ln ;I( cold, pnl.lr latitudes. so link W.Ht'r JS
<br />,n..liIJbJe to conden..!;' (0 prt'CJplt.ltwn. In addition, as
<br />happens to ;lIr 11owln,.: down ;\ mlluntaJO, de-..tcm
<br />fwm hJ~h .dtHuJ(, rt'sults In (omprt'sslllll.d he.lUnf:.
<br />Jnd rht, hot dr~. .Ilr rt"mo\'es e\'en mort" water from
<br />l.lnd surf.lct:s
<br />
<br />\Vatcr. Aquatic Habitats,
<br />and thc Impacts uf Humans
<br />
<br />[ssentlall\" the only w.\tt'[ a\'.lll.lble tll this \'.lSt.
<br />.lflJ re~llln Ilfl.l"IO,l(t'~ on mllUntJ.lllS hl~h ahme rht,
<br />Jt'st.'rr tl11()r~ The hl~h]JnJs JOl(:rcept mo\'emt.'nf of
<br />.lir nl.lsses, furunt: rht:m upwuJ Cl1 (onl ;IllJ
<br />condtnst. rhelr sp.IrSC humldlCleS IntO preclpJt;uion,
<br />\\"lnrt'r smlwp.\(ks .Ic(umul.ltc. melt JO spring, .loJ
<br />~t:t'r Inhl sh.dlo\\ sods or fllfm o\erl.lllJ fl\'ulc[s.
<br />Seeps .lod fl\'ulers comhl[l(' Cl1 form hflJOks which
<br />t'mer""" from the mllllnt.lln Iri)nts \VaH'r In such
<br />dl.lnnels mostly pernllatt.s lOW (ht, ClIJ.fSe.gralllt.d
<br />\.;l1Il:~' Ilonrs, wht're- pr(l(t:'ded If.lm t:\'.lpllr.uion It IS
<br />SWrt-J or (lllltJOUI;'S on .1 subsurf;l.(c parh fl) tht' sea.
<br />Only (h.lnnels with ~uhst.lntJ.l] mlllltJ.nt:
<br />warersheds support perennl.l] strc,lms. Thl;' Colorado
<br />RI\'t:r 1{',e1f oripn;ltes III rhe Rocky ;\lc1ullt3lllS to
<br />tlow through Grt"at R,ISIll .Ill.! ~h)ha\'e dt'st'rrs to
<br />enter tht: Gulf ~)f C.llitorllla surroundeJ hy Sunof.ln
<br />Descrr. The GiLl RIH'r. mLlsr s'lurht:rn maltlr
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