LOCATION STEVIE MTEstablished Series
TAXONOMIC CLASS: Ashy over loamy-skeletal, amorphic over mixed, superactive, frigid Typic Udivitrands
TYPICAL PEDON: Stevie gravelly silt loam, forested (colors are for moist soil unless otherwise noted).
Oi--0 to 1 inch; undecomposed and partially decomposed forest litter.
A--1 to 2 inches; very dark grayish brown (10YR 3/2) gravelly silt loam, grayish brown (10YR 5/2) dry; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many fine and medium and common very fine and coarse roots; 15 percent gravel and 5 percent cobbles; slightly acid (pH 6.2); abrupt wavy boundary. (1 to 4 inches thick)
Bw1--2 to 8 inches; dark yellowish brown (10YR 4/4) gravelly silt loam, yellowish brown (10YR 5/4) dry; weak fine subangular blocky structure parting to fine and medium granular; soft, very friable, nonsticky and nonplastic; many fine and medium and common very fine and coarse roots; 15 percent gravel and 5 percent cobbles; slightly acid (pH 6.2); gradual wavy boundary. (6 to 12 inches thick)
Bw2--8 to 18 inches; dark yellowish brown (10YR 4/4) gravelly silt loam, light yellowish brown (10YR 6/4) dry; moderate fine and medium subangular blocky structure parting to moderate fine granular; soft, very friable, nonsticky and nonplastic; common fine, medium and coarse roots; 25 percent gravel and 5 percent cobbles; moderately acid (pH 6.0); abrupt wavy boundary. (8 to 15 inches thick)
2E/Bw--18 to 43 inches; E part (80 percent) is grayish brown (10YR 5/2) very cobbly sandy loam, light gray (10YR 7/2) dry, Bw part (20 percent) is brown (10YR 5/3) very cobbly sandy loam, very pale brown (10YR 7/3) dry; weak fine subangular blocky structure; slightly hard, friable, nonsticky and slightly plastic; common fine, medium, and coarse roots; 30 percent gravel and 20 percent cobbles; slightly acid (pH 6.2); gradual wavy boundary. (12 to 30 inches thick)
2C--43 to 60 inches; grayish brown (10YR 5/2) extremely cobbly sandy loam, light gray (10YR 7/2) dry; massive; slightly hard, friable, nonsticky and slightly plastic; few medium and coarse roots; 40 percent gravel and 30 percent cobbles; slightly acid (pH 6.2)
TYPE LOCATION: Sanders County, Montana, 400 feet east and 1400 feet north of the SW corner of section 35, T. 26 N., R. 32 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 43 to 47 degrees.
Volcanic glass content in the 0.02 to 2.0 mm fraction - 12 to 20 percent.
Acid-oxalate extractable Al plus 1/2 Fe - 1.60 to 2.25 percent.
Phosphate retention - 25 to 75 percent.
15-bar water retention on air dried samples - 8 to 12 percent.
Note: Some pedons contain a 2E horizon.
A horizon
Value: 4 or 5 dry; 2, 3, or 4 moist
Chroma: 2 or 3 dry; 1, 2, or 3 moist
Clay content: 2 to 10 percent
Bulk density: 0.85 to 1.00 g/cc
Rock fragments: 15 to 25 percent--15 to 20 percent gravel, 0 to 5 percent cobbles
Reaction: pH 5.6 to 6.5
Bw1 horizon
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 3 or 4 dry; 4 or 6 moist
Clay content: 2 to 10 percent
Bulk density: 0.85 to 1.00 g/cc
Rock fragments: 15 to 30 percent--15 to 25 percent gravel, 0 to 5 percent cobbles
Reaction: 5.6 to 6.5
Bw2 horizon
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 3, 4, or 6 dry, 4 moist
Clay content: 2 to 10 percent
Bulk density: 0.85 to 1.00 g/cc
Rock fragments: 15 to 30 percent--15 to 25 percent gravel, 0 to 5 percent cobbles
Reaction: 5.6 to 6.5
2E/Bw horizon
Value: E part 5, 6 or 7 dry, 3, 4 or 5 moist; B part 5, 6 or 7 dry, 3, 4 or 5 moist
Chroma: E part 2 or 3; B part 3 or 4 dry
Clay content: 2 to 10 percent
Rock fragments: 45 to 60 percent--20 to 40 percent gravel, 15 to 30 percent cobbles
Reaction: 5.6 to 6.5
2C horizon
Value: 6 or 7 dry; 4, 5, or 6 moist
Chroma: 1, 2, or 3 dry; 1, 2, 3, or 4 moist
Clay content: 2 to 10 percent
Texture: sandy loam, loamy sand or loamy coarse sand
Rock fragments: 60 to 80 percent--35 to 50 percent gravel; 20 to 30 percent cobbles
Reaction: 5.6 to 6.5
COMPETING SERIES:
Bonnash (MT) - formed in mixed alluvium and glacial outwash; receives less than 28 inches of precipitation; has a frost-free period of 90 to 105 days; is well drained.
Bouldercreek (ID) - does not have 2E/Bw horizon; has 2BC horizon; formed in material from schist or quartzite bedrock.
Dewberry (MT) - does not have 2E/Bw horizon; formed in glacial outwash.
GEOGRAPHIC SETTING:
Landform- mountains.
Elevation - 2,500 to 5,200 feet.
Slope - 15 to 70 percent.
Parent material - volcanic ash over colluvium.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 24 to 40 inches.
Mean annual temperature - 38 to 45 degrees F.
Frost-free period - 70 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS:
DRAINAGE AND PERMEABILITY: Excessively drained, moderate permeability to the 2E/Bw horizon, and moderately rapid permeability below.
USE AND VEGETATION: Stevie soils are used for woodland and wildlife habitat. Potential native vegetation is mainly ponderosa pine, douglas fir, western larch, grand fir, western hemlock and western redcedar. Understory vegetation is mainly twinflower, white spirea, serviceberry, blue huckelberry, queencup beadlily, myrtle pachistima and other forbs and shrubs.
DISTRIBUTION AND EXTENT: Stevie soils are of small extent in the mountains of northwestern Montana. MLRA 43A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Sanders County, Montana 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Volcanic ash mantle - 1 to 18 inches; (A, Bw1, Bw2 horizons);
Cambic horizon - 18 to 43 inches (2E/Bw horizon); and
Particle-size control section - the 1 to 40 inches (A, Bw1, Bw2, 2E/Bw horizons).
Stevie soils have a frigid temperature regime and a udic moisture regime.
ADDITIONAL DATA: Soil Interpretation Record MT1517.