LOCATION MIDDLECREEK COTentative Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Cumulic Haplocryolls
TYPICAL PEDON: Middlecreek loam on a south facing, 4 percent slope in rangeland at an elevation of 7,000 feet. (Colors are for dry soil unless otherwise noted.) The soil was described in October 1978.
A1--0 to 7 inches; very dark grayish brown (10YR 3/2) loam, very dark brown (10YR 2/2) moist; weak medium subangular blocky structure parting to moderate fine granular; soft, very friable, slightly sticky and slightly plastic; many fine and very fine roots; few fine tubular pores; neutral (pH 6.8); clear smooth boundary.
A2--7 to 14 inches; very dark grayish brown (10YR 3/2) loam, very dark brown (10YR 2/2) moist; moderate medium subangular blocky structure parting to moderate fine subangular blocky; soft, very friable, slightly sticky and slightly plastic; many fine and very fine roots; few fine tubular pores; neutral (pH 6.8); clear smooth boundary.
Bw1--14 to 20 inches; dark grayish brown (10YR 4/2) sandy clay loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure parting to weak fine subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common fine roots; few fine tubular pores; neutral (pH 7.0); clear smooth boundary.
Bw2--20 to 35 inches; grayish brown (10YR 5/2) sandy clay loam, very dark grayish brown (10YR 3/2) moist; weak coarse subangular blocky structure parting to weak medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common fine roots; few fine tubular pores; neutral (pH 7.0); clear smooth boundary.
C--35 to 60 inches; grayish brown (10YR 5/2) sandy clay loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; few fine tubular pores; neutral (pH 7.2).
TYPE LOCATION: Routt County, Colorado; about 8 miles southwest of Hayden; about 2,200 feet south and 300 feet east of the northwest corner of Sec. 31, T. 6 N., R. 89 W. U.S.G.S. Quad. Breeze Mountain, Lat. 40 degrees, 26 minutes, 00 seconds N., and Long. 107 degrees, 25 minutes, 39 seconds W., NAD 27
RANGE IN CHARACTERISTICS:
Soil moisture: The soil moisture regime is udic (bordering on ustic)
Mean annual soil temperature: 38 to 42 degrees F.
Mean summer soil temperature: 52 to 58 degrees F.
Thickness of the mollic epipedon ranges from 16 to 60 inches.
Particle size control section (weighted average):
Clay content: 20 to 27 percent
Rock fragments: 0 to 5 percent sandstone and shale gravel.
A horizons:
Hue: 7.5YR, 10YR
Value: 2 to 4 dry, 2 or 3 moist
Chroma: 1 to 3, dry or moist
Texture: silt loam, loam
Organic matter: 2 to 4 percent
Bw horizons (an AC horizon in some pedons):
Hue: 7.5YR, 10YR
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 2 to 4 dry, 1 to 3 moist
Texture: sandy clay loam, loam
Reaction: neutral or slightly alkaline, 6.6 to 7.8
Organic matter: 1 to 2 percent
C horizons:
Hue: 7.5YR, 10YR
Value: 4 to 6 dry, 4 or 5 moist
Chroma: 2 or 3, dry or moist
Texture: sandy clay loam, loam
Reaction: neutral to moderately alkaline, 6.6 to 8.4
COMPETING SERIES: These are the Adderton, Menbar, and Silas series. Adderton soils have a discontinuity with sandy textures below. Menbar soils are somewhat poorly drained. Silas soils are moderately well drained.
GEOGRAPHIC SETTING:
Parent Material: Alluvium derived from sandstone and shale
Landform: alluvial fans, flood plains, and flood plain steps
Slope: 1 to 10 percent
Elevation: 6,600 feet to 8,500 feet
Mean annual air temperature - 37 to 41 degrees F.
Mean annual precipitation - 18 to 25 inches somewhat evenly distributed throughout the year.
Frost-free period: 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Winevada, Skyway, and Zoltay soils. All of these soils are on hills and structural benches above the Middlecreek soils. All of these soils also have thinner mollic epipedons.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate permeability; rare, brief flooding March through June due to snow melt.
USE AND VEGETATION: These soils are used for livestock grazing and wildlife habitat. Native vegetation consists of basin wildrye, slender wheatgrass, Lettermans needlegrass, mountain big sagebrush, mountain snowberry, mountain brome, and western wheatgrass.
DISTRIBUTION AND EXTENT: Northwest Colorado, LRR E, MLRA 48A, small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Routt County, Colorado, 2004. Name is taken from a local drainage called Middle Creek.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon (Cumulic feature): The zone from 0 to 35 inches (The A and Bw horizons). An irregular decrease in carbon is inferred from the landscape position.
Particle size control section: the zone from 10 to 40 inches (Part of the A2 horizon, the Bw horizons, and part of the C horizon)
The soil has an ustic udic moisture regime and a cryic temperature regime.