LOCATION RELSOB WYEstablished Series
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive, frigid Ustic Haplargids
TYPICAL PEDON: Relsob sandy loam-rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 3 inches; brown (10YR 5/3) sandy loam, dark brown (10YR 4/3) moist; moderate medium granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine, fine, and common medium roots; moderately alkaline (pH 7.9); abrupt smooth boundary. (1 to 4 inches thick)
Bt1--3 to 12 inches; yellowish brown (10YR 5/4) sandy clay loam, dark yellowish brown (10YR 4/4) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, friable, sticky and plastic; many very fine, fine and common medium roots; common thin clay films on faces of peds and as bridges between sand grains; mildly alkaline (pH 7.6); clear wavy boundary.
Bt2--12 to 15 inches; light yellowish brown (10YR 6/4) gravelly sandy clay loam, yellowish brown (10YR 5/4) moist; strong medium prismatic structure parting to strong medium subangular blocky; slightly hard, friable, sticky and plastic; common very fine, fine, and medium roots; many moderately thick clay films on faces of peds; 15 percent pebbles; mildly alkaline (pH 7.6); abrupt wavy boundary. (Combined thickness of Bt horizon is 11 to 17 inches.)
2C--15 to 60 inches; lightly yellowish brown (10YR 6/4) very gravelly loamy sand, yellowish brown (10YR 5/4) moist; massive; slightly hard, very friable, nonsticky, nonplastic; few very fine, fine, and medium roots to 28 inches; 40 percent pebbles; mildly alkaline (pH 7.6).
TYPE LOCATION: Fremont County, Wyoming; approximately 960 feet south and 670 feet west of the NE corner of sec. 33, T. 27 N., R. 92 W.
RANGE IN CHARACTERISTICS: Depth to the base of the argillic horizon and strongly contrasting coarse material is 12 to 20 inches. These soils are noncalcareous throughout. The mean annual soil temperature ranges from 36 to 46 degrees F., and the mean summer temperature is 59 to 62 degrees F. EC is less than 2 mmhos throughout the soil.
The A horizon has hue of 2.5Y through 7.5YR, value of 4 through 6 dry, 3 through 5 moist, and chroma of 2 or 3. Reaction is neutral through moderately alkaline (pH 6.6-8.0.)
The Bt (argillic) horizon has hue of 10YR or 7.5YR, value of 5 or 6 dry, 4 or 5 moist, and chroma of 2 through 4. Texture is sandy clay loam or gravelly sandy clay loam with clay ranging from 20 to 35 percent, silt from 0 to 28 percent, and sand from 45 to 80 percent. Coarse fragments range from 0 to 20 percent and are fine or very fine pebbles. Reaction is neutral or mildly alkaline.
The 2C horizon has hue of 2.5Y through 7.5YR, value of 5 through 8 dry, 4 through 7 moist, and chroma of 2 through 6. Texture of the matrix is sand or loamy sand modified with 0 to 60 percent fine pebbles. Reaction is neutral through moderately alkaline.
COMPETING SERIES: These are the Bosler, Millburne, Platoro, and Tigiwon series. Bosler and Millburne soils have a diagnostic calcic horizon above 40 inches. The Platoro and Tigiwon soils have continuous horizons of carbonate accumulations at the base of the Bt horizon and above 40 inches.
GEOGRAPHIC SETTING: Relsob soils are on relict fan aprons and toeslopes of hills and ridges. These soils formed in alluvium derived primarily from noncalcareous sandstone. The finer sediments overlie strata of sand or gravel and sand mixtures. Slopes are 0 to 15 percent and typically simple. Elevation is 6,000 to 7,600 feet. The mean annual precipitation is about 12 inches and ranges from 10 to 14 inches with about half falling as snow or rain in April, May, and early June. The mean annual temperature is about 41 degrees F. and ranges from about 34 to 45 degrees F. The frost-free season is estimated at 80 to 110 days; but, because of elevation, aspect, and air drainage, frost may occur at any time.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bluerim and Ryark soils. Bluerim soils have bedrock at 20 to 40 inches and do not have the strongly contrasting coarse material below the Bt horizon. Ryark soils are very similar but have less than 18 percent clay in the Bt horizon.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate permeability.
USE AND VEGETATION: Rangeland and wildlife habitat. Native vegetation is thickspike wheatgrass, needleandthread, big sagebrush, bluebunch wheatgrass, and Letterman needlegrass.
DISTRIBUTION AND EXTENT: Cold intermountain basins in western Wyoming. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana