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e '! • • UNITED STATES DEPARTMENT OF AGRICULTURE ~'-~ So 11 Censervatlon Service. Colorado Technical Guide Section II E RANGE SITE N0. 281 .r~,~~. V.r~., Field Office RANGE SITE DESCRIPTION for MOUNTAIN OUTWASH Land Resource Area: High Intermountain Valleys (51) .5ctn LN.i S /4'~~ey i A. PHYSICAL CHARACTERISTICS • ~ 1. Physiographic Features This site occupies broad alluvial fans formed by outwash from high mountain ranges. In many places, the fans have coalesced to form a smooth plain that feathers out to a flat valley floor. In some places, they form low benches or terraces above stream courses. There are some minor undulations caused by small drain- , ageways, but most of the site has smooth topography and some is nearly level. Slopes are mostly 0 to 3$ and are not significant to plant growth. Elevation Js 7600 to about 8000 feet. 2. Climatic Features Average annual precipitation Is 7 to 9 Inches. Of this, 55$ to • 60$ falls between May 1 and September 1, mostly from hard, spotty thundershowers of short duration In Juiv and August. May And June are normally dry. Wide seasonal and yearly variations are common. Most maJor plats make their main growth between mid^May and late July, but growth may extend Into September. Some of the main grasses start earlier and complete growth by mid-June. There may be late re-growth on some of these. 3. Native (potential) Vegetation A fairly uniform stand of grasses with a few low shrubs give the site a typically smooth appearance. Blue grams is usually the most abundant crass. But taller grasses, mostly cool-season species, make up a significant part of the annual production, Of these, squlrreltall, western wheatgrass, and Indian ricegrass are most important. There are usually small amounts of needle-and-thread, sand dropseed Fendler three-awn needleleaf sedge and silmst~n ~..-