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<br />flood was the flattening out of the crest dWB to the natural storage
<br />afforded by the area inundated.' ' , ,
<br />Above La Junta the effect of chnnfiel. storage in flattening the crest
<br />was obscured by. the flood flows from the tributary streams, which in-
<br />creased the maximum discharge greatly. Below La Junta the flow
<br />from tributaries was small and the storage effect more marked, as
<br />shown by the decrease in maximum discharge from 200,000 second-
<br />feet at La Junta to 170,000 second-feet at the Amity canal, at a dis-
<br />tance of 51 miles, and to 120,000 second-feet at Holly, at an additional
<br />distance or 37 miles,
<br />The flattening of the flood crest was compensated by its greater
<br />duration. At Pueblo it lasted () minutes; at La Junta, 45 minutes;
<br />and at Amity canal, 3-1 hours. ' The duration of the crest at Holly is
<br />not known, but it must have been several hours.
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<br />TOPOGRAPHY OF AHKANSAS BASIN.
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<br />The part of the Arkansas drainage basin lying in 'Colorado is
<br />roughly rectangular and occupies the southeastern quarter of.the
<br />State. Its northwest corner reaches the heart of the Rocky Moun-
<br />tains near Leadville, It little west of the center iDf the State. Arkan-
<br />sas River is formed by the junction of East Fork and 'Tennessee
<br />Fork, each of which rises i~ the Continental Divide at an elevation
<br />of 11,000 feet or more. From the junction of the two rorks, 3 miles
<br />west of Leadville, the river flows southeastward Tor 840 miles to a
<br />point near Cotopaxi, then turns llnd follows an easterly course for
<br />245 miles to the State line. Tn the upper part of its COllrse it flows
<br />throllg-h mount.ainous ('olmtry ill [l 1I:1IT<lIV \'lllley formed by pnrnllel
<br />mnuntain rangl'So Between Coto.pa"i and Canon City it cuts through .,.'
<br />the front range of mountains, and a few miles helow Callon City it-', ;',-'"
<br />enters the llpper end of the open valley. This valley gradually:.:::
<br />widens until. it merges into the Great Plains a few miles west of
<br />Pueblo. '. ' , ,,' ._m"__
<br />The drainage basin east of the mountains lies in the western po~-
<br />tion of the Great Plains, which exte~ld' from the foot of the Rocky
<br />Mountains 'to the Mississippi Valley. These plains present, wide
<br />areas of smooth'surface traverSed by the broad, shallow valley of
<br />Arkansas River and .m.?~~~l~..s deeply.~..u~ b:y_~~~ ~8:.rro:w;::val~~s_~'~<'
<br />of ll!ter!l1 streams.)Smooth surfaces and eastward-slopmg plams.,
<br />~ ';;re the char~cterisfic features, especially of the uplands, but in parts:; ;;'
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<br />of the region there are buttes, extended escarpments, and canyons of
<br />considerable depth.s One of these butf;es is Baculite Mesa, northeast
<br />of Pueblo, which rises 400 feet from the plain,
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<br />. Darton, N, R.. Gpology and underground, waters of Arkansas Yallpy, COlo,: U, S,
<br />Goo!. SUrvey Prof. Pa per 52, p, 8, 1906.
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