LOCATION WALLROCK           WY
Established Series
Rev. AJC/JEI/JAL
12/2001

WALLROCK SERIES


The Wallrock series consists of very deep, somewhat poorly drained soils that formed in alluvium. Wallrock soils are in concave areas and drainageways of mountainsides and foothills. Slopes are 0 to 25 percent. The mean annual precipitation is about 17 inches. The mean annual air temperature is about 40 degrees F.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive Oxyaquic Argicryolls

TYPICAL PEDON: Wallrock sandy loam, rangeland. (Colors are for dry soil unless otherwise stated.)

A1--0 to 2 inches; very dark grayish brown (10YR 3/2) sandy loam, very dark brown (10YR 2/2) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine, few medium roots; neutral (pH 6.8); abrupt smooth boundary. (2 to 10 inches thick)

A2--2 to 10 inches; very dark gray (10YR 3/1) sandy loam, black (10YR 2/1) moist; weak medium prismatic structure parting to fine subangular blocky; soft, very friable, slightly sticky and slightly plastic; common very fine and fine, few medium roots; neutral (pH 7.2); clear wavy boundary. (5 to 10 inches thick)

Bt1--10 to 15 inches; brown (10YR 4/3) sandy clay loam, dark brown (10YR 3/3) moist; moderate fine prismatic structure parting to moderate fine subangular blocky; slightly hard, very friable, moderately sticky and moderately plastic; common very fine and fine, few medium roots; faint patchy clay films on faces of peds; common strong brown mottles; neutral (pH 7.2); clear wavy boundary. (5 to 10 inches thick)

B22t--15 to 22 inches; yellowish brown (10YR 5/4) sandy clay loam, dark yellowish brown (10YR 4/4) moist; moderate medium prismatic structure parting to strong fine angular blocky; hard, firm, moderately sticky and moderately plastic; common very fine, fine, and medium roots; faint continuous clay films on faces of peds; common strong brown mottles; neutral (pH 7.2); clear wavy boundary. (0 to 10 inches thick)

BC--22 to 40 inches; yellowish brown (10YR 5/4) sandy clay loam, dark yellowish brown (10YR 4/4) moist; massive; hard, firm, moderately sticky and moderately plastic; few very fine, fine, and medium roots to 26 inches; many strong brown mottles; neutral (pH 7.2); clear wavy boundary. (15 to 20 inches thick)

Ck--40 to 60 inches; mixed, dark yellowish brown (10YR 4/4) and brownish yellow (10YR 6/6) sandy loam, yellowish brown (10YR 5/6) moist; massive; hard, firm, slightly sticky and slightly plastic; calcareous; secondary lime mainly disseminated; slightly alkaline (pH 7.8).

TYPE LOCATION: Washakie County, Wyoming; 1,400 feet south, 1,350 feet west of the NE corner sec. 34, T.47N., R86W.

RANGE IN CHARACTERISTICS: The mollic epipdon is 7 to 15 inches thick. Depth to continuous horizons of calcium carbonate accumulation is usually 40 to 48 inches but ranges to 35 inches. The lower boundary of the Bt horizon ranges in depth from 15 to 30 inches. The mean annual soil temperature is 39 degrees to 42 degrees F. Rock fragments less than 3 inches in size range from 0 to 15 percent.

The A horizon has hue of 2.5Y or 10YR, value of 3 through 5 dry, 2 or 3 moist, and chroma of 1 through 3. It is loam or sandy loam. This horizon is neutral or slightly acid.

The Bt horizon has hue of 2.5Y or 10YR, value of 3 through 6 dry, 2 through 4 moist, and chroma of 3 or 4. It is loam, clay loam, or sandy clay loam, and has 18 to 35 percent clay. This horizon has few or common strong brown mottles. It is neutral or slightly acid.

The BC and Ck horizons have hue of 2.5Y or 10YR. It is neutral or slightly alkaline.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Wallrock soils are in concave areas and drainageways of mountainsides and foothills. Slopes are 0 to 25 percent. The soils formed in alluvium from granite, shale, sandstone, or limestone. Elevation is 6,500 to 9,000 feet. The mean annual precipitation is 17 to 25 inches. The mean annual temperature is 34 degrees to 40 degrees F. The frost-free season is less than 60 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bachus, Granile, Clayburn, Lakehelen, Nathrop, Starley and Woosley soils. Bachus, Nathrop, and Woosley soils are well drained and have bedrock at depths of 20 to 40 inches. Granile and Lakehelen soils are well drained and have an albic horizon. Clayburn soils are well drained. Starley soils are well drained and have bedrock at depths of less than 20 inches.

DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow to moderate runoff; moderate permeability. A water table exists above a depth of one meter for sufficient durations to saturate the soils for as long as 90 days or longer.

USE AND VEGETATION: These soils are used for rangeland. Native vegetation is Idaho fescue, tufted hairgrass, slender wheatgrass, sedges and rushes.

DISTRIBUTION AND EXTENT: In the Bighorn Mountains and foothills of north-central Wyoming. The series is of small extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Washakie County, Wyoming, 1976.

REMARKS: Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the soil surface to 15 inches (A1, A2, Bt1 horizons); an argillic horizon from 10 to 22 inches (Bt1, Bt2 horizons); horizon of secondary carbonate accumulation from 40 to 60 inches (Ck horizon).


National Cooperative Soil Survey
U.S.A.