LOCATION USK WAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, isotic, mesic Vitrandic Haploxerolls
TYPICAL PEDON: Usk ashy loam - woodland. (Colors are for dry soils unless otherwise stated.)
Oe--0 to 1 inch; very dark grayish brown (10YR 3/2) moist; partially decomposed organic litter composed of pine needles, leaves, twigs, and cones; slightly acid (pH 6.2); abrupt smooth boundary. (1 to 2 inches thick)
A--1 to 10 inches; grayish brown (10YR 5/2) ashy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, nonsticky and slightly plastic; many fine and few medium and coarse roots; many very fine irregular pores; 10 percent fine pebbles; slightly acid (pH 6.2); clear wavy boundary. (7 to 12 inches thick)
Bw--10 to 20 inches; pale brown (10YR 6/3) gravelly loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and few medium and coarse roots; many very fine irregular pores; 20 percent fine pebbles; slightly acid (pH 6.4); clear wavy boundary. (8 to 13 inches thick)
BC--20 to 27 inches; light yellowish brown (10YR 6/4) gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; common fine and few medium and coarse roots; many fine irregular pores; 30 percent fine pebbles; slightly acid (pH 6.4); clear wavy boundary. (5 to 10 inches thick)
C--27 to 33 inches; light yellowish brown (10YR 6/4) gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; massive; slightly hard, friable, slightly sticky and nonplastic; few fine, medium, and coarse roots; many fine irregular pores; 30 percent fine pebbles; slightly acid (pH 6.4); abrupt wavy boundary. (0 to 8 inches thick)
Cr--33 to 51 inches; light gray weathered granite light gray (10YR 7/2), brown (10YR 5/3) moist; crumbles to very gravelly loamy coarse sand when broken.
TYPE LOCATION: Pend Oreille County, Washington; 3,000 feet east of the southwest corner of section 26, T. 30 N., R. 44 E., WM.
RANGE IN CHARACTERISTICS: The depth to a paralithic contact with weathered granitic bedrock is 20 to 40 inches, and depth to hard rock is more than 40 inches. The soil is usually moist in all horizons but is dry in all parts between 8 to 24 inches for 60 to 75 consecutive days following the summer solstice. The mean annual soil temperature at 20 inches is 47 to 49 degrees F. The control section averages 15 to 35 percent rock fragments mostly 2 to 5 mm pebbles. The mollic epipedon is 7 to 12 inches thick. Reaction is neutral to slightly acid. Some pedons have a stony surface layer.
The A horizon has a value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3 moist and dry. The structure ranges from fine and medium granular to fine and medium subangular blocky.
The Bw horizon has value of 5 or 6 dry, 3 or 4 moist, and chroma of 3 or 4 moist and dry. The structure ranges from fine or medium granular to fine or medium subangular blocky. The texture is gravelly loam or gravelly sandy loam with 15 to 35 percent rock fragments.
The BC and C horizon has value of 5 through 7 dry, 4 to 5 moist, and chroma from 2 through 4 moist and dry. The texture is gravelly sandy loam or gravelly loamy coarse sand with 15 to 35 percent rock fragments. The structure is fine to coarse subangular blocky or may be massive. Some pedons have bands of dark brown (10YR 3/3) sandy loam in the lower part of the profile which ranges in thickness from fine (0.5 cm) to medium (15 cm).
COMPETING SERIES: These are the Donavan, Fourmound, Goldlake, and Spokane series. Donavan soils lack a paralithic contact within depths of 40 inches. Fourmound soils are deep to a lithic contact. Goldlake soils have dense till at 40 to 60 inches. Spokane soils are dry in all parts between 8 and 24 inches for 75 to 90 consecutive days following the summer solstice.
GEOGRAPHIC SETTING: Usk soils are on granitic mountainsides and ridgetops. Slopes are usually convex or complex. Slopes range from 0 to 65 percent, but are predominantly 20 to 65 percent. Elevations range from 1,800 to 3,000 feet. These soils formed in material weathered from granitic rocks with an admixture of volcanic ash and loess in the upper part. These soils occur in a continental climate having warm, dry summers and cool, moist winters. The mean annual precipitation ranges from 24 to 30 inches; and the mean annual temperature is 45 to 47 degrees F. The frost-free season ranges from 110 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hartill, Moscow, Mobate, Newbell, Raisio, Scrabblers, and Skanid soils. Hartill and Newbell soils are loamy-skeletal and frigid. Mobate and Skanid soils are shallow and loamy-skeletal. Moscow and Mobate soils are frigid. Raisio soils are loamy-skeletal. Scrabblers soils are sandy and frigid.
DRAINAGE AND PERMEABILITY: Well drained; slow to very rapid runoff; moderate permeability.
USE AND VEGETATION: These soils are used for grazed woodland, wildlife habitat, watershed, and recreation. Small soil areas are cultivated. Alfalfa, small grains, and grasses are common crops. Native vegetation includes ponderosa pine and Douglas-fir, with an understory of common snowberry, redstem ceanothus, ninebark, wild rose, creambush oceanspray, arrowleaf balsamroot, lupine, yarrow, strawberry, bluebunch wheatgrass, pinegrass, Idaho fescue, and dogbane.
DISTRIBUTION AND EXTENT: Mountain areas of northeastern Washington. Series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Pend Oreille County Area, Washington, l981.
REMARKS: Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the surface to 10 inches and a cambic horizon from 10 to 27 inches. The upper 10 inches of this pedon is estimated to have volcanic glass content of 5 to 20 percent, acid-oxalate extractable aluminum plust one-half of the acid-oxalate extractable iron of 0.4 to 1.0 percent and 15-bar water retention of less than 12 percent. This description reflects a change in classification from Coarse-loamy, mixed, mesic Vitrandic Haploxerolls to Coarse-loamy, isotic, mesic Vitrandic Haploxerolls.