LOCATION WESTSUM OKEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, thermic Udertic Argiustolls
TYPICAL PEDON: Westsum silty clay loam - on a 2 percent slope in cropland. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 10 inches; dark gray (10YR 4/1) silty clay loam, very dark gray (10YR 3/1) moist; weak fine subangular blocky structure parting to weak fine granular; hard, friable; common fine roots throughout; few slightly effervescent spots (HCl, unspecified); moderately alkaline (pH 7.8); abrupt smooth boundary. (5 to 10 inches thick)
Bt1--10 to 16 inches; dark gray (10YR 4/1) silty clay, very dark gray (10YR 3/1) moist; moderate medium blocky structure parting to strong very fine blocky; very hard, firm; few fine roots; few fine tubular, and common very fine tubular pores with low vertical continuity; few fine fragments of siltstone; many distinct clay films on faces of peds; few worm casts; few very slightly effervescent spots (HCl, unspecified); moderately alkaline (pH 8.0); clear smooth boundary. (6 to 13 inches thick)
Btk1--16 to 30 inches; grayish brown (10YR 5/2) silty clay, dark grayish brown (10YR 4/2) moist; few fine faint yellowish brown (10YR5/4) mottles; moderate very fine and fine blocky structure; very hard, very firm; few very fine tubular pores with low vertical continuity; few fine fragments of siltstone; few distinct dark gray (10YR 4/1) streaks of surface material in cracks; common distinct clay films on faces of peds; many fine irregular soft masses of calcium carbonate; few medium and few fine rounded calcium carbonate concretions; strongly effervescent (HCl, unspecified); moderately alkaline (pH 8.0); gradual smooth boundary. (10 to 19 inches thick)
Btk2--30 to 36 inches; grayish brown (10YR 5/2) silty clay, dark grayish brown (10YR 4/2) moist; moderate very fine and fine blocky structure; very hard, very firm; few very fine tubular pores with low vertical continuity; few fine fragments of siltstone; common distinct clay films on faces of peds; few distinct dark gray (10YR 4/1) streaks of surface material in cracks; common fine irregular soft masses of calcium carbonate, and few medium rounded calcium carbonate concretions; strongly effervescent (HCl, unspecified); moderately alkaline (pH 8.0); gradual smooth boundary. (0 to 8 inches thick)
Bt2--36 to 52 inches; light brownish gray (10YR 6/2) silty clay, grayish brown (10YR 5/2) moist; few fine faint light yellowish brown (10YR 6/4) mottles; moderate fine blocky structure; very hard, very firm; few very fine tubular pores with low vertical continuity; few fine fragments of siltstone; common distinct clay films on faces of peds; few distinct dark gray (10YR4/1) streaks of surface material in cracks; slightly effervescent (HCl, unspecified); moderately alkaline (pH 8.0); gradual smooth boundary. (9 to 28 inches thick)
Bt3--52 to 65 inches; light brownish gray (2.5Y 6/2) silty clay, grayish brown (2.5Y 5/2) moist; moderate fine blocky structure; very hard, very firm; few fine and very fine fragments of siltstone; common distinct clay films on faces of peds; few fine rounded dark concretions; moderately alkaline (pH 8.0); gradual smooth boundary. (0 to 13 inches thick)
BC--65 to 80 inches; light brownish gray (2.5Y 6/2) silty clay, grayish brown (2.5Y 5/2) moist; weak fine subangular blocky structure; very hard, very firm; common very fine shale fragments; few faint clay films on faces of peds; common very fine rounded dark concretions, few medium rounded calcium carbonate concretions, and common fine rounded calcium carbonate concretions; very slightly effervescent (HCl, unspecified); moderately alkaline (pH 8.0). (0 to 21 inches thick)
TYPE LOCATION: Noble County, Oklahoma; about 7 miles east and 4 miles south of Billings; 650 feet north and 150 feet west of the southeast corner Section 8, T. 23 N., R. 1 W.
RANGE IN CHARACTERISTICS: The thickness of the solum is over 55 inches, and the depth to shale is over 60 inches. Thickness of the mollic epipedon ranges from 12 to 18 inches. Depth to secondary carbonates ranges from 10 to 23 inches.
The A horizon has hue of 10YR, value of 3 or 4, and chroma of 1 or 2. Texture is silty clay loam or silt loam. Reaction ranges from mildly alkaline to moderately alkaline. Some pedons have a BA horizon. The BA horizon, where present has hue of 10YR, value of 4, and chroma of 2. Reaction ranges from mildly alkaline to moderately alkaline.
The Bt1 horizon has hue of 10YR, value of 3 to 5, and chroma of 1 to 3. Texture is silty clay or silty clay loam.
The Btk1 horizon has hue of 10YR to 2.5Y, value of 4 to 6, and chroma of 2 or 3. Texture is silty clay or silty clay loam. A few pedons have a few brownish yellow or yellowish brown mottles, and a few pedons have slickensides in this horizon.
The Btk2 horizon, where present has hue of 10YR to 5Y, value of 5 or 6, and chroma of 2. Texture is silty clay. A few pedons have a few brownish yellow, light yellowish brown, yellowish red, or yellowish brown mottles, and a few pedons have slickensides in this horizon.
The Bt2 horizon has hue of 10YR to 5Y, value of 5 or 6, and chroma of 2 to 4. A few pedons have a few brownish yellow, light yellowish brown, yellowish red, or pink mottles, and a few pedons have slickensides in this horizon.
The Bt3 horizon has hue of 7.5YR to 2.5Y, value of 5 or 6, and chroma of 2 to 4. A few pedons have a few brownish yellow mottles, and a few pedons have slickensides in this horizon.
The BC horizon has hue of 7.5YR to 5Y, value of 5 or 6, and chroma of 1 to 4. Texture is silty clay or clay loam. A few pedons may have slickensides in this horizon.
The C horizon, where present has hue of 10YR to 5Y, value of 5 or 6, and chroma of 2 to 4. Texture is weathered bedrock or shaly clay.
The Cr horizon, where present has hue of 10YR to 5Y, value of 4 to 6, and chroma of 2 to 4. It is shale bedrock.
COMPETING SERIES: These are the Brewer, Brewless, Dilworth, Piedmont, Renthin, and Wetbeth series in the same family. Brewer and Brewless soils are on floodplains. Dilworth and Piedmont soils have shale bedrock within 40 inches, and Piedmont soils have hue of 5YR or redder throughout. Renthin soils have hue of 5YR or redder throughout. Wetbeth soils are developed in Pleistocene alluvium and have a water table within 30 to 60 inches.
GEOGRAPHIC SETTING: Westsum soils are on very gently sloping to gently sloping foot slopes or back slopes on uplands in the Central Rolling Red Prairies. Slopes range from 1 to 5 percent. The soil formed in material weathered from clayey, gray Permian shale. Mean annual temperature ranges from 57 to 61 degrees F. Thornthwaite annual P-E indices range from 48 to 60.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Dilworth series, and the Grainola, Highview, Kirkland, and Renfrow series. Dilworth, Grainola, and Highview soils are on more sloping back slopes of hillsides above the Westsum soils. Kirkland and Renfrow soils are on higher parts of the landscape.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; very slowly permeable.
USE AND VEGETATION: The principal use is for cropland or rangeland. The principle crop is wheat. Native vegetation is little bluestem, big bluestem, indiangrass, sideoats grama, hairy grama, blue grama, and buffalograss.
DISTRIBUTION AND EXTENT: Central Rolling Red Prairies of Oklahoma and Kansas. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES PROPOSED: Noble County, Oklahoma; 1991.
REMARKS: These soils were formerly mapped in the Summit series.
Diagnostic horizons and features recognized in this pedon: Mollic Epipedon - the zone froom the surface to 16 inches (A and Bt1 horizons).
Argillic horizon - the zone from 10 to 65 inches (Bt horizons).
Soil Interpretation Record: OK0365 Westsum Series