LOCATION POWDERWASH COEstablished Series
TAXONOMIC CLASS: Coarse-loamy over clayey, mixed over smectitic, superactive, frigid Ustic Haplargids
TYPICAL PEDON: Powderwash loamy sand, rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 3 inches; pale brown (10YR 6/3) loamy sand, dark brown (10YR 3/3) moist; weak medium platy structure parting to weak fine granular; soft, very friable, nonsticky and nonplastic; neutral (pH 7.2); abrupt smooth boundary. (2 to 5 inches thick)
Bt1--3 to 6 inches; brown (10YR 4/3) sandy clay loam, dark brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate coarse subangular blocky; hard, firm, sticky and slightly plastic; common distinct clay films on ped faces; neutral (pH 7.2); clear wavy boundary. (3 to 4 inches thick)
Bt2--6 to 15 inches; yellowish brown (10YR 5/4) sandy loam, brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate coarse subangular blocky; slightly hard, friable, slightly sticky and nonplastic; few faint clay films on ped faces; neutral (pH 7.2); clear wavy boundary. (6 to 14 inches thick)
2BC--15 to 22 inches; light yellowish brown (10YR 6/4) coarse sandy loam, brown (10YR 5/3) moist; moderate medium prismatic structure; soft, very friable, nonsticky and nonplastic; 10 percent fine pebbles; neutral (pH 7.3); abrupt smooth boundary. (4 to 12 inches thick)
3BC--22 to 28 inches; light olive brown (2.5Y 5/4) and pale yellow (2.5Y 7/3) clay, olive brown (2.5Y 4/4) and light olive brown (2.5Y 5/3) moist; moderate medium prismatic structure, very hard, firm, sticky and plastic; mildly alkaline (pH 7.4); clear wavy boundary. (0 to 6 inches thick)
3C--28 to 38 inches; greenish gray (5GY 6/1), pale yellow (5Y 7/3) and olive (5Y 5/4) clay, greenish gray (5GY 5/1), and olive (5Y 5/3 and 5Y 4/4) moist; massive; very hard, firm, sticky and plastic; 30 percent soft shale fragments; mildly alkaline (pH 7.6); clear wavy boundary. (3 to 12 inches thick)
3Crk1--38 to 48 inches; greenish gray (5GY 6/1) and olive (5Y 5/6) shale bedrock; 15 percent visible soft white carbonate masses and streaks; strongly alkaline (pH 8.6); gradual wavy boundary. (8 to 12 inches thick)
3Crk2--48 to 60 inches; variegated greenish gray (5GY 6/1) and light reddish brown (5YR 6/3) clay shale bedrock; 5 percent soft white visible carbonate streaks; moderately alkaline (pH 8.4).
TYPE LOCATION: Moffat County, Colorado; approximately 16 miles east of Powderwash, and 2,000 feet north and 5 feet east of the southwest corner of Sec. 30, T. 11 N., R. 94 W. Longitude: 108 degrees, 0 minutes, 2 seconds west. Latitude: 40 degrees, 52 minutes, 58 seconds north.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 43 to 47 degrees F., and mean summer soil temperature ranges from 61 to 66 degrees F. The moisture control section in most years is moist in all parts for 45 or more consecutive days in April and May, dry in all parts for 60 or more consecutive days immediately following July 1, and moist in some but not all parts in October through March. Depth to contrasting clayey substratum is 15 to 30 inches. Depth to calcium carbonate ranges from 25 to 40 inches. The paralithic contact is at a depth of 20 to 40 inches. The upper part of the particle-size control section averages 12 to 18 percent clay, 10 to 20 percent silt, and 60 to 80 percent sand. The lower part of the control section ranges from 35 to 50 percent clay, 30 to 40 percent silt, and 10 to 25 percent sand.
The A horizon has hue of 10YR or 7.5YR, value of 5 or 6 dry, 3 or 4 moist, and chroma of 2 or 3. Reaction is neutral or mildly alkaline.
The Bt horizon has hue of 10YR or 7.5YR, value of 4 through 6 dry, 4 or 5 moist, and chroma of 3 or 4. It is sandy loam or sandy clay loam. Reaction is neutral or mildly alkaline.
The 2BC or 3BC horizons have hue of 2.5Y through 7.5YR, value of 4 through 7 dry, 4 through 6 moist, and chroma of 3 or 4. Clay content averages 10 to 40 percent. Reaction is neutral or mildly alkaline. Pebbles range from 0 to 10 percent.
The 3C horizon has variegated colors with hues of 5GY to 2.5YR, value of 4 through 7 dry, 4 through 6 moist, and chroma of 3 through 6. It is clay loam or clay. Reaction is mildly alkaline or moderately alkaline.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Powderwash soils are on hillslopes and benches. Slopes range from 2 to 15 percent. The soil formed in materials with contrasting textures. The upper half of the soil formed in aeolian and residuum from sandstones. The lower half formed in residuum derived from clay shales. Elevation ranges from 6,100 to 6,800 feet. The mean annual precipitation ranges from 11 to 13 inches and is evenly distributed throughout the year. July is the driest month for the growing season. Over 50 percent of the precipitation is received as snow. Mean annual temperature ranges from 42 to 45 degrees F. and mean summer temperature ranges from 63 to 68 degrees F. The frost-free period is about 75 to 95 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ryark, Rock River, Maysprings, and Maybell soils. All these soils are deep and lack a clayey substratum. Ryark has the same upper profile characteristics and is in a coarse-loamy family. Maybell is in a sandy family.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderately rapid permeability in the upper portion of the soil profile and very slow in the lower portion.
USE AND VEGETATION: These soils are used for rangeland. Native vegetation consists of big sagebrush, western wheatgrass, junegrass, and bluegrasses.
DISTRIBUTION AND EXTENT: Northwestern Colorado. The series is of small extent. Total area is about 4,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Moffat County (Moffat County Area), Colorado, 1991.
REMARKS: The name Powderwash is taken from a small town 16 miles west of the type location. Diagnostic horizons and features recognized in this pedon are: The argillic horizon - the zone from 3 to 15 inches. A paralithic contact is at 38 inches. Borollic feature - organic carbon content and soil temperature regime meets the requirements for Borollic. Last updated by the state 12/90.