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GUNNISON AREA, COLORADO
<br />ous in the lower 4 inches. The substratum is strongly
<br />calcareous, light-brown loam that extends to a depth of
<br />60 inches.
<br />Evanston soils are at elevations of about 8,000 to
<br />10,000 feet. Summers are cool, and winters are cold.
<br />The average annual soil temperature is less than 45° F.
<br />The average annual precipitation is about 14 inches.
<br />Tlie native vegetation is commonly Arizona fescue,
<br />mountain muhly, and needlegrass. Big sagebrush and
<br />rabbitbrush are the principal shrubs.
<br />Permeability is slow. Roots can penetrate to a depth
<br />of 60 inches or more, and available water capacity is
<br />high.
<br />Most of the acreage is used for irrigated native pas-
<br />ture and hay. Small areas are in native range that is
<br />used by both livestock and wildlife.
<br />Typical profile of Evanston loam, I to 5 percent
<br />slopes, in a road cut; NEl/4 sec. 7, T. 46 N., R. 3 W.,
<br />Gunnison County:
<br />AI-0 to 6 inches, dark-brown (7.6YR 4/2) loam, dark
<br />brown (7.6YR 3/2) moist; moderate, medium, gran-
<br />ular structure; slightly hard, friable; pH 7.0; clear,
<br />wavy boundary.
<br />Blt-C, to 9 inches, dark-brown (7.6YR 9/2) loam, dark
<br />brown (7.5YR 3/2) moist; weak, medium, sub-
<br />angular blocky structure parting to moderate, fine,
<br />subangular blocky; hard, friable; thin patchy clay
<br />films on pad faces; pH 7.2; clear, smooth boundary.
<br />B2t~9 to 14 inches, brown (7.5YR 5/4) clay loam, dark
<br />brown (7.5YR 4/4) moist; moderate, coarse, sub-
<br />angular blocky structure parting to moderate, me-
<br />dium to fine, subangular blocky; very hard, firm;
<br />thin continuous clay films on pad faces; pH 7.2;
<br />clear, vary boundary.
<br />Baca-14 to 18 inches, brown (7.6YR 5/4) heavy loam, dark
<br />brown (7.5YR 9/4) moist; weak, medium, sub-
<br />angular blocky structure parting to weak, fine, sub-
<br />angular blocky; hard, friable; calcareous; pH 7.8;
<br />gradual, smooth boundary.
<br />Cca-18 to 60 inches }, light-brown (7.5YR 6/4) loam,
<br />brown (7.SYR 6/4) moist; massive; hard, friable;
<br />5 to 10 percent rounded and angular cobblestones;
<br />calcareous; calcium carbonate in few fine concre-
<br />tions and in thin seams :rod streaks; pH 8.4.
<br />The A horizon is typically loam, but in places is gravelly
<br />loam and sandy loam. it ranges from 3 to 10 inches in thick-
<br />ness and from brown to dark brown in color. The B horizon
<br />ranges from brown to light brown. Depth to lime ranges
<br />from 12 to 20 inches. The content of gravel and cobblestones
<br />ranges from 0 to 15 percent.
<br />Evanston loam, 1 to 5 percent slopes (EvB).-This soil
<br />is on alluvial fans and valley-fill slopes, mainly along
<br />Ohio and Tomichi Creeks and their tributaries. It has
<br />the profile described as representative of the series.
<br />Included with this soil in mapping are small areas
<br />of Dewville and Curecanti soils and, along Ohio Creek
<br />and the East River, small areas of Fola soils and steep
<br />gravell}• terrace edges. Also included are saline spots
<br />and wet areas, which are identified by spot symbols
<br />nn the soil map. Included soils make up less than 10
<br />percent of the total acreage.
<br />Most of the acreage is irrigated and produces good
<br />yields of meadow hay and pasture. Runoff is medium
<br />to slow. The erosion hazard is slight in areas protected
<br />Ily a plant cover of hay or pasture, but it is moderate
<br />during snowmelt and in areas where vegetation is
<br />sparse. Capability units Vc-1 irrigated, VTe-2 non-
<br />in•igated; Mountain Outwash range site.
<br />17
<br />Evanston loarm~,6 to 20 ercen slo ]es h-This
<br />so] 1~1's on al~uvla' ans an va ey s] es t roughout the
<br />central part of the survey area. It is commonly in areas
<br />at the outlets of streams and side drainageways.
<br />Included with this soil in mapping are steep cobbly
<br />terrace edges and small areas of Dewville and Mergel
<br />soils and Alluvial land. Included soils make up 15 per-
<br />cent of the total acreage.
<br />Most of the acreage is native range and is used far
<br />grazing. fields of meadow hay are moderate to good
<br />where irrigation water is available. Runoff is medium
<br />to rapid. It accumulates on surrounding soils, concel]-
<br />trates in drainageways, and creates gullies. The ero-
<br />sion hazard is moderate. Capability units VIe-1 irri-
<br />gated, VIe-2 nonirrigatecl; Mountain Outwash range
<br />site.
<br />Fola Series
<br />The Folx ,cries consists of deep, well-drained soils
<br />on alluvial fans and terraces. Slopes are 1 to 8 percent.
<br />These soils formed in cobbly and sandy alluvium that
<br />was derived from a wide variety of rocks.
<br />In a representative profile the surface layer is brown
<br />cobbly sandy loam about 6 inches thick. The subsoil is
<br />reddish-brown very cobbly sandy loam about 10 inches
<br />thick. The substratum to a depth of 60 inches is brown
<br />very cobbly sandy loam.
<br />Fola soils a]•e at an elevation about 8,200 feet. The
<br />average annual precipitation is about 14 inches. The
<br />average annual soil temperature is 42° F. The native
<br />vegetation is commonly big sagebrush, western wheat-
<br />grass, Arizona fescue, and native bluegrass.
<br />Permeability is rapid. Roots cal] penetrate to a depth
<br />of 60 inches or more, but available water capacity is low.
<br />Fola soils are important for ir]igated hay and pas-
<br />tu re.
<br />Representative profile of Fola cobbly sandy loam in
<br />a road cut on the east side of Cement Creek; sec. 27, T.
<br />14 S., R. 85 W., Gunnison County:
<br />Al-0 to 6 inches, brown (7.6YR 6/2) cobbly sandy loam,
<br />dark brown (7.6YR 4/2) moist; weak, very fine,
<br />granular structure; soft, very friable; 30 percent
<br />gravel and cobblestones; pH 7.4; gradual, smooth
<br />boundary.
<br />B2-0 to 10 inches, reddish-brown (6YR 6/3) very cobbly
<br />sandy loam, reddish brown (5YR 4/3) moist; moder-
<br />ate, medium, subangular blocky structure; slightly
<br />hard, very friable; small amount of gelatinous coat-
<br />ings on some coarse fragments; 60 percent cobble-
<br />stones and gravel; pH 7.4; gradual, smooth bound-
<br />ary.
<br />C-16 to 60 inches, brown (7.5YR 6/B) very cobbly sandy
<br />loam, dark brown (7.6YR 9/3) moist; massive;
<br />soft, very friable; 70 percent gravel and cobble-
<br />stones; pH 7.6.
<br />The A horizon is typically cobbly sandy loam, but in
<br />places is sandy loam, stony loam, and loam. it is 4 to 12
<br />inches thick. The B and C horizons are 36 to 80 percent
<br />gravel end cobblestones.
<br />Fola cobbly sandy loam, 1 l0 8 percent slopes (FoB).-
<br />Thissoil is on stream terraces and alluvial fans through-
<br />out the surveil area. In some areas it has a thin organic
<br />mat at the surface.
<br />Included with this soil in mapping are small areas of
<br />Gateview cobbly loam and Curecanti gravelly loam.
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