LOCATION COWTOWN COEstablished Series
TAXONOMIC CLASS: Fine, smectitic Umbric Haplocryalfs
TYPICAL PEDON: Cowtown loam, on a west facing, simple, 15 percent slope in spruce-fir woodland at an elevation of 10,100 feet. (Colors are for dry soil unless otherwise noted.)
A1--0 to 3 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; 7 percent gravel; many very fine roots; neutral (pH 6.6); clear smooth boundary. (2 to 6 inches thick)
A2--3 to 5 inches; grayish brown (10YR 5/2) silt loam, dark brown (10YR 3/3) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; 7 percent gravel; many very fine roots; slightly acid (pH 6.4); clear smooth boundary. (0 to 4 inches thick)
E--5 to 16 inches; light gray (10YR 7/2) cobbly silt loam, brown (10YR 5/3) moist; moderate medium subangular blocky structure parting to moderate fine granular; slightly hard, friable, slightly sticky and slightly plastic; 15 percent gravel, 10 percent cobble; few very fine and fine roots; few very fine oblique discontinuous pores; moderately acid (pH 6.0); gradual wavy boundary. (5 to 14 inches thick)
Bt1--16 to 33 inches; light gray (10YR 7/2) silty clay, brown (10YR 5/3) moist; many medium distinct yellowish brown (10YR 5/6) lithochromic mottles due to variable parent material; moderate fine angular blocky structure; hard, firm, slightly sticky and plastic; many distinct clay films on faces of peds and in pores; few very fine and medium roots; few very fine and fine oblique discontinuous tubular pores; moderately acid (pH 5.8); clear smooth boundary. (10 to 40 inches thick)
Bt2--33 to 60 inches; pale brown (10YR 6/3) silty clay, yellowish brown (10YR 5/4) moist; moderate fine angular blocky structure; hard, firm, slightly sticky and plastic; many distinct clay films on faces of peds and in pores; moderately acid (pH 5.8).
TYPE LOCATION: Dolores County, Colorado; about 3 miles northwest of Dunton, Colorado; located in an unsectionized area about 2,000 feet west and 1,300 feet south of the of the projected northeast corner of Sec. 24, T. 41 N., R. 12 W.; Groundhog Mountain USGS quad; lat. 37 degrees 48 minutes 21 seconds N. and long. 108 degrees 08 minutes 18 seconds W., NAD 27
RANGE IN CHARACTERISTICS:
Soil moisture regime: udic; dry in some part of the moisture control section for less than 45 cumulative days (typic udic subclass).
Mean annual soil temperature: 34 to 40 degrees F.
Mean summer soil temperature: 40 to 46 degrees F. with an O horizon or 50 to 58 degrees F. without an O horizon.
Depth to the base of the argillic horizon: 30 to 60 inches or more.
Base saturation: 85 to 100 percent (estimated)
Particle-size control section:
Clay content: 35 to 50 percent
Rock fragment content: 0 to 15 percent, mainly gravel and cobble of sandstone and shale origin.
O horizon: some pedons have O horizons
A Horizon:
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3, dry and moist
Texture: L, SIL
Rock fragment content: 0 to 15 percent sandstone and shale fragments
Reaction: slightly acid or neutral
E horizon:
Hue: 7.5YR or 10YR
Value: 6 or 7 dry, 4 to 6 moist
Chroma: 2 to 4 dry and moist
Texture, fine earth fraction: L, SIL
Rock fragment content: 5 to 30 percent
Reaction: moderately acid to neutral
Bt horizon:
Hue: 7.5YR or 10YR
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 2 to 5, dry and moist
Texture: CL, C, SIC
Rock fragment content: 0 to 15 percent
Reaction: moderately acid to neutral
C horizon: (present in some pedons)
Hue: 7.5YR or 10YR
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 2 to 4, dry and moist
Texture: CL, C, SCL
Rock fragment content: 10 to 35 percent, mainly gravel, channers and cobble
Reaction: slightly acid or neutral
COMPETING SERIES: There are currently no competitors. The Harkness series, in a closely related family, is dry for more than 45 cumulative days (ustic udic subclass).
GEOGRAPHIC SETTING:
Parent material: slope alluvium derived mainly from shale.
Landform: mountain slopes.
Slopes: 5 to 60 percent
Elevation: 9,600 to 11,600 feet
Mean annual air temperature: 32 to 38 degrees F.
Mean annual precipitation: 30 to 40 inches.
Wettest months: July and August receive slightly more precipitation than other months.
Driest months: May and June receive the least precipitation, however the soils are still moist from snowmelt.
Frost-free period: 60 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Scout and Powderhorn family soils. Both are on mountain slopes.
Scout soils are loamy-skeletal.
Powderhorn family soils have a mollic epipedon.
DRAINAGE AND PERMEABILITY: Well drained; medium or high runoff; slow permeability.
USE AND VEGETATION: These soils are used for livestock grazing, timber production, and wildlife habitat. Native vegetation consists of Engelmann's spruce, subalpine fir, and an understory of grasses and shrubs consisting of Thurber's fescue, mountain brome, sedge, whortleberry and currant.
DISTRIBUTION AND EXTENT: Mountainous areas of southwest Colorado. LRR E, MLRA 48A. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Dolores County, Animas-Dolores Soil Survey Area, Colorado. 2002. Series proposed in 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 5 inches. (A1 and A2 horizons)
Albic horizon: The zone from 5 to 16 inches (E horizon)
Argillic horizon: The zone from 16 to 60 inches. (Bt1 and Bt2 horizons)
Umbric feature: The A horizons have moist color value of 3 or less and a dry color value of 5 or less after mixing the top seven inches.
Particle size control section: The zone from 16 to 36 inches. (Bt1 and part of the Bt2 horizons)
Keys to Soil Taxonomy: Classified according to the Eighth Edition, 1998