LOCATION COBEY WAEstablished Series
TAXONOMIC CLASS: Ashy, glassy, frigid Humic Vitrixerands
TYPICAL PEDON: Cobey silt loam, in forestland (Colors are for moist soil unless otherwise noted.)
A1--0 to 5 inches, black (10YR 2/1) ashy silt loam, gray (10YR 5/1) dry; moderate fine granular structure; soft, friable, nonsticky, nonplastic; many fine, medium, and coarse roots; few fine gravel; slightly acid (pH 6.4); clear smooth boundary. (3 to 8 inches thick)
A2--5 to 11 inches, very dark brown (10YR 2/2) ashy silt loam, grayish brown (10YR 5/2) dry; weak fine subangular blocky structure; slightly hard, friable, nonsticky, nonplastic; common fine and medium roots; few fine tubular pores; 5 percent gravel; moderately acid (pH 5.8); clear smooth boundary. (4 to 10 inches thick)
A3--11 to 15 inches, very dark grayish brown (10YR 3/2) ashy silt loam, grayish brown (10YR 5/2) dry; weak fine subangular blocky structure; slightly hard, friable, nonsticky, nonplastic; common fine and medium roots; few fine tubular pores; 5 percent gravel; neutral (pH 6.6); clear smooth boundary. (3 to 8 inches thick)
AB--15 to 26 inches, dark brown (10YR 3/3) ashy silt loam, brown (10YR 5/3) dry; weak fine and medium subangular blocky structure; slightly hard, friable, nonsticky, nonplastic; common medium roots; few fine tubular pores; 8 percent gravel; neutral (pH 6.6); clear smooth boundary. (8 to 14 inches thick)
Bw--26 to 42 inches, dark yellowish brown (10YR 3/4) ashy loam, brown (10YR 5/3) dry; weak fine and medium subangular blocky structure; slightly hard, friable, nonsticky, nonplastic; common medium roots; few fine tubular pores; 10 percent gravel; neutral (pH 6.6); clear smooth boundary. (12 to 18 inches thick)
2C--42 to 48 inches, brown (10YR 5/3) very gravelly fine sandy loam, pale brown (10YR 6/3) dry; massive; slightly hard, friable, slightly sticky, nonplastic; common medium roots; few fine tubular pores; 50 percent cobbles and gravel; neutral (pH 6.6).
TYPE LOCATION: Ferry County, Washington; near switchback on forest road; southeast of the southeast of the northwest of sec. 31, T. 37 N., R. 37 E., W.M.
RANGE IN CHARACTERISTICS:
Moisture control section: Moist, but dry for 60 to 75 consecutive days following the summer solstice
Mean annual soil temperature: 44 to 47 degrees F
Particle-size control section: >30 percent volcanic glass in the fine-earth fraction
Content of rock fragments: 0 to 15 percent gravel
Thickness of the mollic epipedon: 20 to 30 inches
Depth to the 2C horizon: >40 inches
A and AB horizons
Value: 2 or 3 moist; 3 to 5 dry
Chroma: 1 to 3
Texture: Silt loam or loam
Reaction: Neutral to moderately acid in the A horizon and slightly acid or neutral in the AB horizon
Bw horizon
Value: 3 or 4 moist; 4 or 5 dry
Chroma: 3 or 4
Texture: Silt loam or loam
Reaction: Slightly acid or neutral
2C horizon
Value: 3 to 5 moist; 5 or 6 dry;
Chroma: 3 or 4
Texture: Fine sandy loam or very fine sandy loam
Content of rock fragments: 20 to 60 percent gravel
Reaction: Slightly acid or neutral
COMPETING SERIES:
Ermabell (OR) has sandy apparent textures throughout the particle-size control section.
Laidlaw (OR) is dry for 90 to 110 consecutive days in normal years; the mollic epipedon is less than 20 inches thick.
Lundgren (OR) is dry for 90 to 110 consecutive days in normal years; the mollic epipedon is less than 20 inches thick.
Pilotbutte (OR) is dry for 75 to 90 consecutive days in normal years; 10 to 40 percent pumiceous sand in the particle-size control section.
Retep (WA) is 20 to 40 inches deep to a paralithic contact.
Suttle (OR) has 15 to 35 percent rock fragments in the particle-size control section.
Trailcreek (ID) is 20 to 40 inches deep to a paralithic contact.
Wanoga (OR) is 20 to 40 inches deep to a lithic contact.
GEOGRAPHIC SETTING:
Landform: Foothills and mountains
Elevation: 2,800 to 4,500 feet
Parent material: Volcanic ash over glacial till
Mean annual precipitation: 18 to 24 inches
Mean annual air temperature: 44 degrees F
Frost-free period: 90 to 120 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Merkley (ID) is loamy-skeletal; has an ochric epipedon.
Nevine (WA+MT) is loamy-skeletal; has an ochric epipedon.
Oxerine (WA) has an ochric epipedon.
Pepoon (WA) is less than 20 inches to bedrock.
DRAINAGE AND PERMEABILITY: Well-drained; medium to rapid runoff; moderate permeability
USE AND VEGETATION: Cobey soils are used mainly for woodland. The potential native vegetation is mainly ponderosa pine, Douglas-fir, western larch, and lodgepole pine with an understory of willow, strawberry, Idaho fescue, pinegrass, and common snowberry.
DISTRIBUTION AND EXTENT: Cobey soils are of moderate extent in northeastern Washington.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Ferry County, Washington, 1971
REMARKS:
Diagnostic horizons and features recognized in this pedon:
a mollic epipedon from the surface to 26 inches >30 percent volcanic ash
a cambic horizon from 26 to 42 inches
base saturation by ammonium acetate >50 percent