LOCATION SPOTTEDHORSE WYEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aridic Paleustalfs
TYPICAL PEDON: Spottedhorse loam -- on a northeast facing slope of 2 percent, utilized as rangeland. (Colors are for dry soil unless otherwise stated)
E--0 to 4 inches; light brownish gray (10YR 6/2) loam, brown (10YR 4/3) moist; strong medium, thin, and very thin platy structure; slightly hard, very friable, nonsticky and slightly plastic; thin vesicular crust on soil surface; many fine and very fine roots; neutral (pH 7.0); abrupt smooth boundary. (2 to 8 inches thick)
Bt--4 to 13 inches; yellowish brown (10YR 5/4) clay, dark yellowish brown (10YR 3/4) moist; strong medium prismatic structure parting to strong medium and fine angular blocky; extremely hard, very firm, very sticky and very plastic; many fine and very fine roots; few prominent dark brown (10YR 3/3) clay films on faces of peds and lining pores and root channels; neutral (pH 7.2); clear smooth boundary. (7 to 18 inches thick)
Btk--13 to 27 inches; light brownish gray (10YR 6/2) clay loam, brown (10YR 5/3) moist; strong coarse prismatic structure parting to strong medium and fine angular blocky; very hard, firm, moderately sticky and moderately plastic; many fine and very fine roots; few distinct dark brown (10YR 3/3) clay films on faces of peds and in pores; strongly effervescent; common fine irregular light gray (10YR 7/2) threads of calcium carbonate; moderately alkaline (pH 8.4); clear smooth boundary. (0 to 16 inches thick)
Bk--27 to 35 inches; light gray (10YR 7/2) clay loam, brown (10YR 5/3) moist; moderate medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common fine roots; strongly effervescent; common fine irregular very pale brown (10YR 8/2) threads of calcium carbonate; moderately alkaline (pH 8.4); clear wavy boundary. (8 to 18 inches thick)
Cr--35 to 60 inches; soft shale; slightly effervescent in the upper 9 inches and noneffervescent below.
TYPE LOCATION: Campbell County, Wyoming; about 600 feet north and 2,300 feet east of the southwest corner of section 5, T. 55 N., R. 74 W. Reservoir Creek, WY USGS topoquadrangle; 44 degrees 46 minutes 04 seconds north latitude and 105 degrees 47 minutes 35 seconds west longitude.
RANGE IN CHARACTERISTICS: Depth to bedrock is 20 to 40 inches. Depth to the base of the argillic horizon is 11 to 29 inches. Depth to accumulations of calcium carbonate is 10 to 19 inches. Rock fragments are commonly less than 5 percent channers but range from 0 to 10 percent. The moisture control section is usually moist in in some or all parts in March through June. The average annual soil temperature is 47 to 50 degrees F.
The E horizon has hue of 10YR or 2.5Y, value of 4 to 7 dry and 3 to 5 moist, and chroma of 2 to 4. It is very fine sandy loam, loam or fine sandy loam. It is neutral or slightly alkaline.
The Bt horizon has hue of 10YR or 2.5Y, value of 4 to 6 dry and 3 to 5 moist, and chroma of 2 to 4. Texture is clay loam, clay, silty clay or silty clay loam. It has 35 to 55 percent clay and 10 to 25 percent fine and coarser sand. It is neutral or slightly alkaline.
The Btk horizon has hue of 10YR or 2.5Y, value of 4 to 6 dry and 4 or 5 moist, and chroma of 2 to 4. Texture is clay loam, clay, silty clay or silty clay loam with 35 to 50 percent clay. It has 4 to 12 percent calcium carbonate equivalent. It is slightly alkaline or moderately alkaline.
The Bk horizon has hue of 10YR or 2.5Y, value of 5 to 7 dry and 4 or 5 moist, and chroma of 2 through 6. Texture is commonly clay loam or clay and less commonly silty clay, silty clay loam, silt loam, loam, or sandy clay loam. It has 4 to 14 percent calcium carbonate equivalent. It is moderately alkaline or strongly alkaline.
Some pedons have a C horizon.
The Cr horizon is commonly soft shale and less commonly interbedded shale and sandstone. It is typically effervescent in the upper part and noneffervescent in the lower part, but may be noneffervescent throughout in some pedons.
COMPETING SERIES: These are the Bleumont, Brislawn and Jaywest series. These competing soils are very deep. In addition, Brislawn soils are moderately deep to fragmental porcelanite.
GEOGRAPHIC SETTING: Spottedhorse soils are on relict terraces, plateaus, fan remnants, broad ridges, and on hillslope positions including backslopes, footslopes, and toeslopes. They formed in residuum or alluvium over residuum derived primarily from shale. Slopes are 0 to 15 percent. Elevations are 3,500 to 5,000 feet. The mean annual precipitation ranges from 15 to 17 inches, half of which falls as rain or snow from March through June. The mean annual air temperature ranges from 44 to 50 degrees F. The frost-free season is about 105 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Jaywest and the Echeta, Leiter, Moorhead, Samsil and Cromack soils. Echeta and Cromack soils have cambic horizons and are calcareous throughout. Leiter and Moorhead soils lack albic horizons and do not have an absolute increase in clay of more than 15 percent within a vertical distance of 1 inch at the upper boundary of the Bt horizon. Samsil soils are shallow.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff, depending upon slope; slow permeability.
USE AND VEGETATION: These soils are utilized as rangeland, hayland and pasture, nonirrigated cropland, and wildlife habitat. The native vegetation is mainly needleandthread, western wheatgrass, blue grama, and green needlegrass. Winter wheat, oats, barley, and alfalfa are the principle cultivated crops.
DISTRIBUTION AND EXTENT: Spottedhorse soils occur in the Powder River basin of north-central and northeastern Wyoming. The series is of limited extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Campbell County, Wyoming, Southern Part; 1995.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Albic horizon - 0 to 4 inches (E)
Argillic horizon - 4 to 27 inches (Bt, Btk)
An absolute increase in clay of more than 15 percent within a vertical distance of 1 inch at the upper boundary of the Bt horizon.
SIR- WY1373
LRR- G