Laserfiche WebLink
<br />. <br /> <br />!'- <br />o <br />o <br />(X) <br /> <br />. <br /> <br />. <br /> <br />DESCRIPTION OF BASI~ <br /> <br />most other parts of the Vnited States. ~ost of the moisture for precip- <br />itation on the Upper Basin is derived from the Pacific Ocean ani the <br />Gulf of )-lexica. The Pacific source predominates Renerally from October <br />throURh ApT i 1 and tht:' Cu 1f source dUT in~ the b [t' spr tOR and e.'lr ly summer. <br /> <br />1:1 the northern f."ITt of the basin most precipitation falls in the <br />form of winter snows and spring rains. Summer storms ilre infrequent <br />but are sometimes of cloudburst intensity in localized areas. In the <br />more arid s)uthern portion the principal rainy season is in the winter <br />months 'Jith occasional localized cloudbursts in Ul(' summer .,00 fall. <br /> <br />Extremes of temperature in the basin range from 500 F. below zero <br />to 1300 F. above ZL~ro. TIle northern portion of the h.'1sin is character- <br />i7..~d by short, ~rm summers and long, cold winters, and many mountain <br />;lro.>3S are blanketed by deep snow all winter. The southern portion of <br />tlte rosin has long, hot summers, practically continuous sunshine, and <br />almost complete absence of freezing temperatures. <br /> <br />~;evertheless, the entire basin is arid except in the extremely high <br />altitudes of the headW3ters art'as. Rainfall averages .'1S 10'" as 2.5 inch(>s <br />In the southern end of the tAsin ....hile total precipitation in the high <br />'lIOllntains may ran~e from 40 to 60 inches annually. <br /> <br />D. Vege ta tion <br /> <br />Areas of higher elevation are covered with forests of pine, fir, <br />spruce, and silver-stemmed aspens, broken by smnll glades nnd mountain <br />meadows. Pinon and juniper trees, interspersed ..'ith scrub oak, mountain <br />mahogany, rabbit brush, bunch ~rasses, and similar pli1nts Rrow in the <br />intermediate elevations of the mesa and plateau regions. LarRe areas <br />in the Upper Basin are dominated by biR sagehrush and rl~lated v('getation. <br />Hany of the streams are bordered by cotton~lods, willows, and s.-1.lt cL>dar. <br />Scattered cottonwods and chokecherries ~ro'" in the canyons with the <br />cliff rose, the redbud, and blue columbine. A profusion of wildfl(l....ers <br />carpets many mountain parks. At lot..'er elevations large areas are almost <br />completely devoid of plant life ....hile other sections are sprinkled t.:ith <br />desert shrubs, Joshua trees, other Yucca plants, and sa~uaro cacti, some <br />of the latter giant plants reachinR 40 feet in ht:!ight. Occasionally, <br />cotton\o'Qods or desert ....1110""5 are found along desert l-ltreams with mes- <br />quite and creosote hush or catclaw and paloverde. In recent years many <br />river channels have been overrun Iorith tamarisk or salt cedar to the ex- <br />tent that a large volume of -....nter is bein~ consumed by such vegetation. <br /> <br />12 <br /> <br />