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<br />22 Sedimentology and Stratigraphy of the Palisades, lower Comanche. and AllOrO Grande Areas of the Colorado River
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<br />hy ~Ub~L'qlll'l1l tlllOU UL'rth1" 1l1<l~ e'\plallllh~ rdatll<.' Tarl1~ ot'
<br />L'\P\h~U Pit ~nL'~ 1I1 IhL' \\~~tL'm t.;l!lYtln I ~;llrky. ~llf)'l, P II ~ l.
<br />.-h IllL' I1JIl1~ ~uggL'~h. th.' ;\rT(l~(l (,ran,k ,lrL';J I' dliJ.racl<.'r.
<br />in'd by a II ido.'. Uo.'L'P arToy" no.'lll\1rl.. (ligurL' ~2 ) lhal h;b 1ll,'i'.:J
<br />IhL'~(' IL'rr,l(:o.' dt'P"'lh. "'\P.hl11g ..'ultuT;J111l:J1,,'n;11 and ,tr..LIigra-
<br />phy mlhL' arroy., \\all, Th.: arr"yo I1L'II\;'rl.. I~ a, much a,:, m
<br />J.:o.'p In pia.:.:, :\ 'l11alkr. ',,'c'lIlJa~ arro~,l h prL'"o.'I11 dl'l\n-
<br />'lream of IhL' prulliJ~ ~y"ll'rn IliguT': ~ II. 1\ hlch ha, lI1Chl'J .11.5
<br />1ll1lllO IbL' upp.:nl111,,1 ,dll1\ 1,III~rr;I":t. and morl' liMn t m lllll' th.:
<br />tll\Ll'r 1L'rTac<.' lImh\ nld'p"llll nL'dr Ih.'lllI,:ath.n of ~.:..:lIOII:'
<br />Jt''l'nl:>ed ;It Ihh "II.: ~ugge'h lhal ll1L.l'llln o! th.: upr':T1ll,hl h.'r-
<br />r.i.:e 1\ ill ,oon lntTt';bo.'.
<br />Th.: 111;1l1l ,IIT.,y,' ;11 .\rr"YII (ir,mdL' I, ..:.lIl~iJt'rt'J II' h.: ,I
<br />pn:dam t\.';lIUrt'. hL'CaU'l' It b rrL''l'O! III a..'n,ll rhOI"!!r;lrh~ Irl'm
<br />l'IM5 (Iig. ~-'I ThL' e\lell! l,rarTll~" do.'\dllpnlL'Ill,lppo.'ar' lal
<br />ka~1 qualll.llil\'ly I h, h;J\l' in..:re,l'l'd ,in..'L' ]<)115, hnm L'\.umn;J-
<br />lh'n of ,terL'll p;llr, I.f 19<,:' pIK*'gr.Jph,. hUllhL' ~..:al<.' \.1 tlll"l'
<br />Illl;J!!L'" I' ,uL.h Ihalm"rL' d~l,tdeu llll';bUrL'l1lellh oLlrr'lY" li:a-
<br />lun:" in 1')n5 \\mIlJ 1101 he rdtabk Rejle:IIL'd gTt.t1lld-Il;l~':jl,llld
<br />plu1lngrallllllelTle lllarpmg by Pedep,r'11 .lIld 111h..'r' (~tl\l~ IlillmJ
<br />hllk ..:hange mlhL' deplh ,111.1 ":1111Iig:urallun "LlrwY\l' ;J1'-\rT<lYU
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<br />Figure 21 Aerial view 01 Ihe Arroyo Grande area Iphotographs from
<br />tl1eGrand Canyon Monlloflrlgand Research Center. laken Irl May
<br />20021. larger. scale view lAI Shows localions of aenal views In B.and
<br />01 the dune Shown,n an obhquevLewIIlltgure2J locallonsotstrall.
<br />graphlcseclJOns Ilhrough 11 are shown In B In B. a smaller, second.
<br />ary arroyo nel\vork IS vIsible 10 Ihe eastolthe malrl arroyo JsectlOn 5
<br />is Inthesecondary arrovo River dlschafge IS 226 m'/s
<br />
<br />(ir,lJlde hL.tor\.' anJ alier Ihe :::oo~ mlln~"(lll 'ea'>1.In. Ihe <lflly
<br />1.'\..'cpllon b\.'lIlg Ihe p;trtial lilling of;t 111m"r Till \\ 1111 aeolian
<br />~eJi1l1L'nl 1>..'l\\e<.'1I h'hn.l"~ :II1J O<.:l<lhL'r ~O(l:::.
<br />Th~' 1l1\'ulh (\flhl' rrlma~ aITO~O Jr;Jllh lllh) th<.' n\.:r lIe;lT
<br />Ihl' ..:entl'rufa l:tr"L'~'11 m~r kJi Oig :::11 CU1l1p;Jn'I>ll of
<br />r......:en! ;\en,11 rl1<)logr~h Ih"~L' Ir,'1ll l'-Ih5 ,h,l\\~ lh;lllh~
<br />':\.1.'111 of rip'lTJ;Jn I .:gL'lall"n ha, gre,lll~ lIl..:re.heJ durll1g lh~
<br />P;hl -10 YL'ar'. Jnd IhallhL' area {I( \'IX'I} -.;mJ III IhL' malll e~!J~
<br />.md ;lI"ng Ih<.: .:hann<:1 In;JrJ:1Il ha, .led':;!'..'" (tig~. ::: I ;JnJ :::~ l.
<br />\enal phl'lograrlh l:JkL.I11111ll1l.....11.llclY h.:1l.r..' th.: 1491> tb\>J
<br />e\p.:fIll1':ll1 ;mJ J.g<lin ,1\ month"tlierlho.' rlouJ ,ho\\ thaI a
<br />...md l:>;Jr :. In 1\ Ide (tn.:a,ur.'1..l al a rll L'r dl...:harg.: uf ~~lJ m' ,
<br />[;.;,lHHI 1"1 ~]Ili.lnIlL'J dunllg Ihe l1o<I<..!;JI Ih<.' ;lrr"Y~1 mOUlh 11\ lhe
<br />eddy l>ll rl\cr k-li
<br />fhL' lerraeL' ,urb..:(', llllt' whl.:h lh~' JrT<IYO~ L'U! hal<.' under-
<br />gllnL' dcllall.m hy \\111..1. e\ Itkn..:.:d hy l'...dL'~lal ..kl.:I<'plll~'ll1 (.f
<br />rd)ble~ ,mJ L'uhural .iml:..t..:h \.j up hI :i ...111 ah,.\ '" Ih.: ~lIrrllund-
<br />Ill,\! !;lIIJ 'UrIJL'C <. orr'...l' durlL''' ,Ire (.\lnm"ll ~'n Ihe I.:rra..:e,.
<br />;Ilthough 1\\'11 Je\ \'Il'PL.J L'~ rtogall1lC ":11.1,1 ;mJ cl.l,mi/alu>II by
<br />~r;J"e~. lIle'<.luil.... Jnd 1IlhL"r \ q!L'I,1I1~ll\ mJic;JI... rl'l:lll\ d:- Ill;JL'-
<br />tlh' dllne~ at t111~ Il1llL' .\ !argl'. a..:111 c ,and June " rre,elll al
<br />tIlt' ~'\.trelllL' Ulll\ Ihlrl'~lm end of lh,,: ..\rrl1Y (' (,rand", arL'a. ~I(() 111
<br />J\l\\lhlrL'am "frhL' (L'lller ,lfthL' malll "rr"Yl' ndl\\lrk (lig. ~-1).
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<br />Figure 22. Thema,narroyoneI\VOr,aIArroyoGrande,vlewedtrom
<br />[he nOr1h IAlandSOUlh(BI The large sand dune In lhedlslance InA
<br />fat the downstream end oi thiS areal IS mlgralmg 10 tile north, toward
<br />Ihe arroyonelWork, but ItS sand IS trapped byawlde dralflagejnOI
<br />visible I between the dune and Ihe arroyo, which pre\fentsmuchol
<br />tl1!S sand Irom reacl1mg the lerrace Into I'\Ihlch the arrovo has inCI sed
<br />NOlelhelhlckloneo!npaflanvegetallon
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