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<br /> <br />"FIATER AND P.ELATF.D LAND RESOURCES - <br />IIOLORFS P,IVER BASF <br />COLORADO AND UTAH" <br />A Report Based on a Cooperative Study by <br />Colorado Water Conservation Board and <br />united States Dep?rtment of Agriculture <br />Denver, Colorado - September, 1972 <br />Soil. *lanping Unit 3: _Rock outcrop and very shallow soi]s of the can ons. <br />This apping unit is along [he Dolores and San Niguel Rivers and their <br />tricutaries. Runoff is eery rapid beca~!se of the steep stopes and shallow <br />soils ~:+it~ low cuaterholdine capacities. Sed;.ment yield is from less than <br />0.2 to 1.0 acre-feet per snuare mile per ;rear. <br />The landscape is characterized by deep sandstone canyons with steep slopes <br />and long very narrow valleys, and floodplains. Small, gently sloping mesas <br />are above the canyons. Steeply sloping mesas are above the canyons. <br />Steeply sloping a1lLlvial fans border some of the canyon walls. Numerous <br />intermittent drainageways dissect the. steep slopes. The dominant c~~ver. is <br />nin,ron-juniper. Oakhru.ch, serviceberry; anr~ grass are more abllnd?nt at <br />higher elevations because of increased precipitation. Willows and ~:otron- <br />wood trees occupy small tracts along the narrola valleys. There are a few <br />irri~at?d hay fields where the valleys are wider. <br />This ++nit is composad of two major components. Ahout 45 percent of the <br />t+nit is rock outcrrlp, mainly sandstone, with some small outcrops of shale. <br />Another 49 percent of the unit has shallow soils, less than 20 inches, <br />over underlying sandstone and some shale. These soils are stony anti <br />us+ially have loamy, light-covered surfac? layers. The remaining 6 ;)ercent <br />of the unit is made up of soils caith dark-colored surface layers anct mixed <br />alluvia]. soils in the Dolores and San Ptiguel River bottoms. <br />i.. ,. .,--i'~r. p.:.1 t!on avJ ct~.a: nc[rclsao of colt r~ppl rp vni cs o[ th= •. alo: cs Rtvrr pvtla la Cotorcdv gad Vui <br />rvva,av trmc ~ <br />fo:-m :I ~ioc ;Z cry.+c;Lr..:caet vvuat cvnuat Eue <br />I:rp : of ;ele vv;la n;prrc tp t[vrf on. tc-perv rare' porlod i <br />s}c:roLpc rc.:~:: 19u6 Grcn; Lrou; , SuSg roup or Lard Typc bcsLn (icaQ (Sahel) (]') (dvya) <br />) 45 Roca and sha lc ou [c rope )2.5 4,]C9- ]-l3 <br />25 1!aplczca Llz (sh alloy oaec svndscone and 9.0;0 <br />ahvlc) <br />20 ]orrlor[he ors (shotlov Duet samis cv na <br />and sF.a lc) <br />4 Lirhtc ArpLuatvlls <br />4 boral [s vJ Ctyohoro lls <br />3 .o a![lutc ats <br />Cox invn[ :Dun ina ~t Escl~a etl , <br />ps en[ slope udl:cnr Eroafrn Mo)o: ~ <br />natcrlvla ;(percc n!); Ylc!2 prrSt•~s La rc1 <br />. (RC. (r./ uus <br />sq. sL/ ~ <br />4?_g IO)- <br />160 <br />dstu-.e 15-109 <0.?-LO Xvt~-me sMe[ Raa,e, <br />vlcl ¢ - vl Lt llEr <br />sal., and e~ulc:, da-~a~ <br />au~+t~o ,.yea mea uy <br />