LOCATION WELLSBENCH IDEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Pachic Ultic Argixerolls
TYPICAL PEDON: Wellsbench silt loam, pasture, on a 48 percent slope with a south aspect at an elevation of 2,280 feet. (Colors are for dry soil unless otherwise noted)
A--0 to 6 inches; dark grayish brown (10YR 4/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure parting to moderate fine granular; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine tubular pores; 10 percent gravel; neutral (pH 7.2); clear smooth boundary. (4 to 32 inches thick)
Btl--6 to 14 inches; dark grayish brown (10YR 4/2) gravelly silty clay loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine and fine, and common medium roots; many very fine and fine, and common medium and coarse tubular pores; common faint clay films on peds and in pores; 20 percent gravel and 8 percent cobbles; neutral (pH 7.0); clear wavy boundary.
Bt2--14 to 30 inches; brown (10YR 4/3) very cobbly silty clay loam, dark brown (10YR 3/3) moist; moderate fine prismatic structure; hard, firm, very sticky and very plastic; common very fine, fine, and medium roots; many very fine and fine tubular pores; continuous prominent clay films on faces of peds and in pores; 30 percent cobbles and 10 percent gravel; moderately acid (pH 6.0); abrupt wavy boundary.
Bt3--30 to 41 inches; dark yellowish brown (10YR 4/4) very gravelly silty clay, dark brown (10YR 3/3) moist; moderate fine prismatic structure parting to moderate fine and medium subangular blocky; very hard, very firm, very sticky and very plastic; common fine and medium roots; many very fine and fine tubular, common very fine irregular pores; continuous prominent clay films on faces of peds and lining pores; 30 percent gravel and 10 percent cobbles; moderately acid (pH 6.0); clear wavy boundary. (Bt horizons 23 to 37 inches thick)
R--41 inches; unweathered basalt.
TYPE LOCATION: Clearwater County, Idaho; about 0.75 miles north of Orofino, Idaho; about 1,750 feet south and 1,900 feet east of the northwest corner of section 5, T. 36 N., R. 2 E.; Latitude - 46 degrees, 29 minutes, 42 seconds North; Longitude - 116 degrees, 14 minutes, 04 seconds West. USGS Orofino East quadrangle.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 47 to 54 degrees F. (Mesic temperature regime)
Soil moisture - dry between depths of 4 to 12 inches for 45 to 70 days following the summer solstice. (Xeric moisture regime)
Depth to bedrock - 40 to 60 inches
Thickness of mollic epipedon - 22 to 41 inches
Base saturation - less than 75 percent in the upper 30 inches of the argillic horizon.
A horizon:
Hue - 10YR or 7.5YR dry or moist
Value - 3 to 5 dry, 2.5 or 3 moist
Chroma - 2 to 4 dry, 1 to 3 moist
Clay content - 18 to 26 percent
Rock fragments - 0 to 10 percent gravel
Reaction - slightly acid or neutral
Bt horizons:
Hue - 10YR or 7.5YR dry or moist
Value - 3 to 5 dry or moist
Chroma - 2 to 4 dry or moist
Textures - SICL, GR-SICL, GRV-CL, CBV-SICL, CBX-SICL, GRV-SIC, CBX-C, CB-SICL
Clay content - 28 to 44 percent (weighted average greater then 35 percent in the upper 20 inches of the argillic horizon)
Rock fragments - 10 to 40 percent gravel; 0 to 60 percent cobble, 10 to 80 percent total fragments (weighted average greater than 35 percent in the upper 20 inches of argillic horizon)
Reaction - moderately acid to neutral
COMPETING SERIES: These are the Carrbutte (T), and Skookum series. The Carrbutte series is deep to a paralithic contact. The Skookum series is moderately deep to a lithic contact.
GEOGRAPHIC SETTING: The Wellsbench soils are on benches, canyon sides, and footslopes at elevations of 1,000 to 3,300 feet and have slopes of 2 to 55 percent. These soils are formed in loess and residuum and/or colluvium weathered from basalt. The average annual temperature ranges from 45 to 52 degrees F. The average annual precipitation ranges from 24 to 33 inches and the frost-free season ranges from 90 to 180 days (9 in 10 years to 1 in 10 years, respectively).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Jacket, Keuterville, Kooskia, and Lacy series. Jacket and Kooskia soils average less than 35 percent coarse fragments in the argillic horizon and are in concave positions on plateaus or benches. Keuterville soils have less than 35 percent clay in the upper 20 inches of the argillic horizon and are on steep, convex canyon sides. Lacy soils have a lithic contact at less than 20 inches and are on the convex canyon sides.
DRAINAGE AND PERMEABILITY: Well drained, medium to very rapid runoff, slow permeability.
USE AND VEGETATION: These soils are used for pasture, wildlife habitat, and recreation. Some areas are used for limited timber production. The natural vegetation is Idaho fescue, bluebunch wheatgrass, common snowberry, arrowleaf balsamroot, and widely spaced ponderosa pine.
DISTRIBUTION AND EXTENT: Clearwater County, Idaho. The Wellsbench series is of limited extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Clearwater County, Idaho, 2003.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the surface to 41 inches (A, Bt1, Bt2 and Bt3 horizons).
Argillic horizon - The zone from 6 to 41 inches (Bt1, Bt2, and Bt3 horizons).
Particle-size control section - The zone from 6 to 26 inches (Bt1, and part of the Bt2 horizon).