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<br />frOtHS ~
<br />
<br />.56
<br />
<br />The :;l:l.Il!!"f{' de Cristo Ran!!"" on the {'Il',! sid.' of the ndlpy was
<br />slIbjf'dPd to at It'us! two stltgp,. of g:lll(,jll.liotl tflllt sc:ulplurl'c1 thl' sharp
<br />Ill'sks alld produl"pJ moraint's t.htlt l'xh'udt.d to the ht'lids of lurge
<br />lllluvial lllH,; It! ;'h'vlltioll.~ Ilf 9,000 tfl 9,500 feet. .-\Iong' thl.' foot of the
<br />rang'(' lInd on tilt' pa..,tern side of thl' Clos('d Ba;;in, 8 dl'posit of wind-
<br />blown sands t'rl:'stf'd by tht' pn'\"lliling sOlllll\\-pst{'r!y winds blowing
<br />Il.cro~.. Ihp .,"alle\" flour ht!..'; bN'1l dt~signntt'd tilt' Gr"1l1 ~llnd DUIH>s
<br />XUlional :>.tollurllent.
<br />The mountains on the we,.;! "ide of till' valley 1m' II. purt of the ::-iun
<br />JUllllgfOUp I'Lnd urt' ('OUlJlO,;('J pnn('iplllly uf tt:'rtillry \"o\cunie:;, which
<br />ha\"l' heen ,.;llbjech.d tH at !l'as! thn.t. stngl'-s of glaciation.
<br />'Vilh Pilch uplift of th.. San Juan p(.nephlin, sllbsidem'l' llPllllrCntly
<br />t.ook pla('(' in thc \'il.lIey, The lH'drllrk surftln', it i;; bdil'YI't1, IUS thus
<br />Iwen d,'prl'ssl'd tholl'mnds of feet b,'low Ilw prt.st'nl floor of the "Illley,
<br />Th... l'1l'\'iltion of Ih.. !loor of tilt' vulle)" prnhllbly hIlS not Y1lri..J much
<br />tiS the ralt' of filling and subsidt'IH'A.' wt're probably vefY nendy balanced.
<br />The s{ructum\ bll."iin of the ,'alley is filled with tertiaf\' and qua-
<br />{(>fllary depo,.:it..'l l'ompri,.:ing tilt' ~llntll Ft' llm! AllHllu,,:U formatiolls.
<br />Of Ihe two formation;;, t.IH' '\II)01o"ll, whieh imnwdill.ld,,' undt'rlit'"
<br />much of thl' yalll')" t:Ioor. is uf priuHl.rV eOllcern ill l','aluilting the waIN
<br />salyage potentialities of the Closed Busin.
<br />The AllltnO":ll. formlltion is ('omp,)sf'd of unronsolidll.led gm\"{'I, saud,
<br />silt., lllltl day lllld rallg~" in thickul:'sS up to mort' than 2.000 f('el. The
<br />an>rag:<" thicknes..... of pt'r,'iolls material, llbo\"e the first confining: ("Ia,'
<br />layer of g:em'ral continuity. is llbout 61 fet't. .
<br />
<br />\V.HEn HE~OtJRCEH
<br />
<br />Th(' water r('sourcf'S of the ,'al1f'Y are df'ri\"f'd mainly from snowfall
<br />on that Jlortion of tlw drainagl' in'a nhove 8,000 ff'et in elf'Yfl.t.ion.
<br />Precipitation 011 ttw valley floor, which SVl'fllges ahout 7 inchl';; per
<br />year, Ilug-ments the supply to II small ext.('nt. Exdusiye of this prl:'cipi-
<br />t!ltion on the "nllf',)' floor. the water stll)ply a\'l'rllw'd about 1.-166,400
<br />llcrt'-feet per Yt'ar for th(' pf'riod 1936 t lrolll?:h 1959 ll.nd WM a"nilahle
<br />It.;; fol\ows in the various part.s of the yalley:
<br />
<br />p"~
<br />ojtolol
<br />'I
<br />23
<br />10
<br />,
<br />I'
<br />
<br />Stream:
<br />Hio Grande near Del Nortc______________.______________________
<br />Conejml Ri"'."r Btt.Sin______hP____U___.___._._ _______________
<br />West Sidtl Tributarit':!u___________.. .__u_____.________________
<br />Ea.~t Side TributariCtl_ ___oo,_o__ou__uo__o__o O__'O_'_____n___
<br />Clo~ed B~~in__o_oo___o__o___._.__________o____o___o____o_o____
<br />Total.____________
<br />
<br />100
<br />
<br />IRRIGATIO~
<br />Irrigation farming started in the ,'allf'Y in the 1850's, The first ir-
<br />rigat.f'd nrt's of Il11Y sizf' was 8 b..}t of wheat flmns which extf'ndf'd
<br />from nf'ar Alamosa north.....ard to beyond Hoopf'r, Bl'cause of the poor
<br />drainage characteristics of the area, some of the irrig-ators then began
<br />a general move westward onto the allu\"ial fans where the soils are
<br />naturally well drained. The practict' of subirrigation .....as de\"eloped,
<br />Under such practice, the Vfound-w8ter table is brought up to within
<br />20 to 30 incht:'s of thf' ground slli'fllce by massiw applicutions or
<br />surract:' water during th(' spring runoff. Onc(' the ground-watN table
<br />
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