LOCATION STEPSTONE WAEstablished Series
TAXONOMIC CLASS: Ashy over sandy or sandy-skeletal, glassy over isotic, frigid Typic Vitrixerands
TYPICAL PEDON: Stepstone ashy loam - on a 12 percent northeast facing slope under a Douglas-fir canopy, at 3,700 feet elevation. (Colors are for dry soil unless otherwise stated)
Oi--0 to 0.5 inch; needles, leaves, and twigs.
Oe--0.5 to 0.75 inch; partially decomposed needles, leaves, and twigs; abrupt smooth boundary.
A--0.75 to 1.25 inch; light brownish gray (10YR 6/2) ashy loam, dark grayish brown (10YR 4/2) moist; weak very fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; common fine and medium roots; 2 percent granitic gravel; neutral (pH 6.6); abrupt smooth boundary. (0 to 4 inches thick)
Bw1--1.25 to 7 inches; yellowish brown (10YR 5/4) ashy loam, dark yellowish brown (10YR 3/4) moist; moderate very fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many fine, medium, and coarse roots; 5 percent granitic gravel, 5 percent cobbles, 2 percent stones; neutral (pH 6.6); clear smooth boundary. (4 to 12 inches thick)
Bw2--7 to 19 inches; light yellowish brown (10YR 6/4) ashy loam, brown (7.5YR 4/4) moist; weak very fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; common fine, medium, and coarse roots; 10 percent granitic gravel, 5 percent cobbles; neutral (pH 6.8); clear wavy boundary. (10 to 20 inches thick)
BC--19 to 23 inches; very pale brown (10YR 7/4) gravelly ashy sandy loam, yellowish brown (10YR 5/4) moist; weak very fine subangular blocky structure; soft, friable, nonsticky and nonplastic; common fine and medium roots; 20 percent granitic gravel, 5 percent cobbles; neutral (pH 6.8); clear wavy boundary. (0 to 5 inches thick)
2C1--23 to 35 inches; light gray (10YR 7/2) very stony loamy sand, brown (10YR 5/3) dry; massive; slightly hard, friable, nonsticky and nonplastic; few fine and medium roots; 20 percent granitic gravel, 15 percent cobbles, 15 percent stones; neutral (pH 6.8); gradual wavy boundry. (9 to 25 inches thick)
2C2--35 to 60 inches; very pale brown (10YR 8/2) extremely stony loamy sand, grayish brown (10YR 5/2) moist; massive; slightly hard, friable, nonsticky and nonplastic; few fine and medium roots; 20 percent granitic gravel, 20 percent cobbles, 20 percent stones; neutral (pH 6.8).
TYPE LOCATION: Okanogan County (Colville Indian Reservation), Washington; about 19 miles north of the town of Nespelem; 1,700 feet east, 1,600 feet south of the northwest corner of sec. 33, T. 34 N., R. 31 E., W.M.
RANGE IN CHARACTERISTICS: The mean annual soil temperature at a depth of 20 inches is 44 to 46 degrees F. These soils are usually moist but are dry between depths at 8 and 24 inches for 60 to 75 consecutive days following the summer solstice. Reaction is neutral or slightly acid throughout. The mantle of volcanic ash ranges from 14 to 30 inches thick. The upper part of the 0 to 40 inch particle-size control section has an estimated moist bulk density of 0.65 to 0.85 g/cc, volcanic glass content of 30 to 60 percent, acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 1.0 to 2.0 percent, and 15-bar water retention of 5 to 12 percent for air dried samples. The lower part of the particle-size control section is 35 to 60 percent granitic rock fragments by weighted average.
The A horizon has value of 5 to 7 dry, 3 to 5 moist, and chroma of 2 or 3 dry or moist. It is ashy loam or ashy fine sandy loam. Some pedons have a bouldery surface layer.
The Bw horizon has hue of 10YR or 7.5YR; value of 5 or 6 dry, 3 or 4 moist, and chroma of 3 or 4 dry or moist. It is ashy loam, ashy fine sandy loam or ashy silt loam with 0 to 30 percent granitic rock fragments including 0 to 20 percent gravel, 0 to 15 percent cobbles, and 0 to 10 percent stones.
The BC horizon has value of 6 or 7 dry, 4 or 5 moist. It is gravelly ashy loam or gravelly ashy sandy loam and is 10 to 25 percent granitic gravel and 0 to 10 percent cobbles.
The 2CB and 2C horizon has hue of 10YR or 2.5Y; value of 6 to 8 dry, 5 or 6 moist, and chroma of 2 or 3 dry or moist. It is very gravelly loamy sand, extremely gravelly loamy sand, very stony loamy sand, extremely stony loamy sand or very cobbly loamy sand. It is 20 to 55 percent granitic gravel, 5 to 20 percent cobbles, and 0 to 25 percent stones. The 2CB, when present, is very gravelly sandy loam in the upper few inches.
COMPETING SERIES: These are the Domkey, Limking, and Parmenter series. Limking soils are 40 to 60 inches deep to a lithic contact. Domkey soils are dry for 75 to 90 consecutive days and is sandy loam, coarse sandy loam or fine sandy loam in the fine earth fraction in the upper part of the particle-size control section. Parmenter soils are coarsely stratified and contain rock fragments of mixed mineralogy which include volcanic rocks, schist, phyllite, and granitic rock.
GEOGRAPHIC SETTING: Stepstone soils are on ground moraines, and toeslopes, footslopes, and lower backslopes of mountains. Slopes are 3 to 65 percent. Elevations range from 2,500 to 5,000 feet. These soils formed in glacial till from granitic rocks overlain by a mantle of volcanic ash. The climate is characterized by warm, dry summers and cold, moist winters. Average annual precipitation ranges from 18 to 25 inches. The average January temperature is about 22 degrees F, average July temperature is about 65 degrees F, and the mean annual temperature is about 43 degrees F. The frost-free season (32 degrees F) is 90 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Manley, Merkel, Nevine, and Resner soils and the tentative Mineral soils. Merkel soils are loamy-skeletal and are on mountains. Manley and Resner soils have a cryic temperature regime. Manley soils are on the upper slopes of foothills and mountains. Resner soils are on outwash terraces, terrace escarpments and mountain footslopes and toeslopes. Nevine soils are ashy over loamy-skeletal and are on moraines, foothills and mountains. Mineral soils are loamy-skeletal, are underlain by granitic bedrock at depths of 20 to 40 inches, and are on mountainsides and ridges.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability above the lithologic discontinuity, moderately rapid permeability below.
USE AND VEGETATION: Timber production, grazing, wildlife habitat, and watershed are the principal uses. Native vegetation is Douglas-fir, ponderosa pine, lodgepole pine, and western larch. Understory species include pinegrass, common snowberry, pachystima, white spirea, strawberry, Saskatoon serviceberry, rose, creambush oceanspray, and kinnikinnick.
DISTRIBUTION AND EXTENT: North-central Washington. MLRA 43A. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Okanogan County (Colville Indian Reservation), Washington, 1987.
REMARKS: Diagnostic horizons and features recognized in this pedon are a cambic horizon from 1.25 to 23 inches, and a mantle of volcanic ash from the mineral surface to 23 inches. Based on laboratory data on similar Resner, Nevine, and Elbowlake soils, the mantle has andic soil properties. The description reflects a change in classification from ashy over sandy or sandy-skeletal, mixed, frigid Typic Vitrixerands to ashy over sandy or sandy-skeletal, glassy over isotic, frigid Typic Vitrixerands.