LOCATION ELK MOUNTAIN WYEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Ustic Calciargids
TYPICAL PEDON: Elk Mountain loamy fine sand-rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 4 inches; light brownish gray (10YR 6/2) loamy fine sand; dark grayish brown (10YR 4/2) moist; weak very fine granular structure; soft, very friable, nonsticky and nonplastic; common fine and very fine roots; slightly alkaline (pH 7.4); clear smooth boundary. (2 to 6 inches thick)
Bt1--4 to 12 inches; brown (10YR 5/3) fine sandy loam, brown (10YR 4/3) moist; strong very coarse prismatic structure parting to strong coarse subangular blocky; hard, very friable, slightly sticky and nonplastic; common fine and very fine roots; many thin clay films on all faces of peds; slightly alkaline (pH 7.6); clear smooth boundary.
Bt2--12 to 16 inches; pale brown (10YR 6/3) fine sandy loam, brown (10YR 5/3) moist; moderate very coarse prismatic structure parting to moderate coarse and medium subangular blocky; slightly hard, very friable, slightly sticky and nonplastic; many thin clay films on faces of all peds; slightly alkaline (pH 7.6); gradual wavy boundary. (Combined thickness of Bt horizons is 8 to 25 inches)
Btk--16 to 24 inches; pale brown (10YR 6/3) fine sandy loam, brown (10YR 5/3) moist; weak very coarse prismatic structure parting to weak coarse subangular blocky; slightly hard, friable, slightly sticky and nonplastic; few fine roots; few thin clay skins on vertical faces of peds; strongly effervescent, lime as common soft masses and filaments; strongly alkaline (pH 8.6); gradual wavy boundary. (0 to 10 inches thick)
Bk--24 to 30 inches; very pale brown (10YR 7/3) fine sandy loam, brown (10YR 5/3) moist; massive; slightly hard, very friable, slightly sticky and nonplastic; few very fine roots in upper 2 inches; violently effervescent, lime disseminated and as common soft masses and filaments; strongly alkaline (pH 8.6); abrupt wavy boundary. (8 to 15 inches thick)
Cr--30 to 60 inches; brown and pale brown, soft, calcareous sandstone. The sandstone is weakly stratified with very thin lenses of various textured bedrock. Seams of carbonates run at odd angles along possible ancient freeze-thaw lines.
TYPE LOCATION: Carbon County, Wyoming; about 600 feet east and 50 feet north of the SW corner of sec. 16, T. 16 N., R. 83 W.
RANGE IN CHARACTERISTICS: Depth to bedrock and the paralithic contact ranges from 20 to 40 inches. The soil typically is free of carbonates in the upper 8 to 20 inches unless recharged by run-on water or wind. Depth to the base of the argillic horizon is 10 to 25 inches. Rock fragments range from 0 to 35 percent and are channers or semirounded gravel. About half the coarse fragments break down upon pretreatment. The mean annual soil temperature ranges from 41 to 47 degrees F., and the mean summer temperature ranges from 59 to 64 degrees F. The EC is less than 2 mmhos throughout and is highest in the Bk horizon.
The A horizon has hue of 2.5Y or 10YR, value of 4 through 6 dry, 3 or 4 moist, and chroma of 2 or 3. It is neutral or slightly alkaline. Surface crusting is common in areas devoid of vegetation.
The Bt horizon has hue of 2.5Y through 7.5YR, value of 5 or 6 dry, 4 or 5 moist, and chroma of 2 through 4. Texture typically is sandy loam or fine sandy loam and less commonly loam with 8 to 18 percent clay, 0 to 40 percent silt, and sand from 50 to 80 percent with more than 35 percent being fine or coarser sand. It is neutral or slightly alkaline.
The Bk horizon has hue of 2.5Y or 10YR, value of 4 through 7 dry, 4 through 6 moist, and chroma of 2 through 4. It is fine sandy loam, sandy loam, or loamy sand with 4 to 12 percent clay. Secondary calcium carbonate ranges from 3 to 12 percent. Gypsum is common in some pedons. It is moderately alkaline or strongly alkaline.
A thin C horizon is in some pedons. It has the same color, texture, and reaction as the Bk horizon but lacks the secondary carbonate accumulations. Some pedons have a thin, highly variable 2C horizon immediately above the bedrock.
The Cr horizon is brown or pale brown, soft sandstone. The soil-bedrock interface constitutes a paralithic contact. The bedrock has been observed to be greater than 10 feet thick in most areas.
COMPETING SERIES: These are the Cotha, Rawlins, Ryan Park, and Ryark series. Cotha soils lack carbonates throughout and are neutral or slightly alkaline in the C horizon. Rawlins and Ryan Park soils are deep. Ryark soils are deep and have loamy sand or gravelly sand substrata.
GEOGRAPHIC SETTING: Elk Mountain soils are hill and ridge backslopes, shoulders, footslopes, and summits. These soils formed in residuum and colluvial slopewash weathered from calcareous, soft sandstone. Slopes are both simple and complex and range from 0 to 15 percent. Elevations range from 6,200 to 7,800 feet. The mean annual precipitation ranges from 8 to 14 inches of which about half falls as snow or rain in April, May, and early June. The mean annual temperature ranges from 39 to 45 degrees F. The frost-free season is estimated to range from 60 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Forelle, Satanka, and the competing Ryan Park soils. Forelle soils are deep and have 18 to 35 percent clay in the argillic horizon. Satanka soils have a thin fine-loamy argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate and moderately rapid permeability.
USE AND VEGETATION: Rangeland, wildlife habitat, and limited irrigation. Native vegetation consists of needleandthread, thickspike wheatgrass, Indian ricegrass, and prairie junegrass. Big sagebrush occurs as part of the community on drier sites.
DISTRIBUTION AND EXTENT: Western and southern Wyoming. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Carbon County, Wyoming; 1985.