LOCATION BACKROAD MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Andic Dystrudepts
TYPICAL PEDON: Backroad gravelly ashy silt loam, forested (colors are for dry soil unless otherwise noted).
Oi--0 to 2 inches; undecomposed and slightly decomposed forest litter.
A--2 to 5 inches; grayish brown (10YR 5/2) gravelly ashy silt loam, dark grayish brown (10YR 4/2) moist; weak, fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine, fine, medium, and coarse roots; 20 percent pebbles; slightly acid (pH 6.2); clear wavy boundary. (2 to 4 inches thick)
Bw--5 to 14 inches; light yellowish brown (10YR 6/4) gravelly ashy silt loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine, fine, medium, and coarse roots; 25 percent pebbles; slightly acid (pH 6.2); clear wavy boundary. (7 to 11 inches thick)
2E--14 to 23 inches; very pale brown (10YR 7/3) very gravelly silt loam, brown (10YR 5/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common very fine, fine, medium, and coarse roots; 10 percent cobbles, 40 percent pebbles; slightly acid (pH 6.4); clear wavy boundary. (6 to 15 inches thick)
2E/Bw1--23 to 34 inches; E part (80 percent) is very pale brown (10YR 8/3) extremely gravelly silt loam, pale brown (10YR 6/3) moist, Bw part (20 percent) is very pale brown (10YR 7/4) extremely gravelly silt loam, yellowish brown (10YR 5/4) moist; moderate medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common very fine, fine, medium, and coarse roots; 10 percent cobbles, 60 percent pebbles; slightly acid (pH 6.4); gradual wavy boundary. (8 to 20 inches thick)
2E/Bw2--34 to 60 inches; E part (60 percent) is very pale brown (10YR 8/3) extremely gravelly silt loam, pale brown (10YR 6/3) moist, Bw part (40 percent) is very pale brown (10YR 7/4) extremely gravelly silt loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, friable, nonsticky and nonplastic; few fine, medium, and coarse roots; 15 percent cobbles, 70 percent pebbles; slightly acid (pH 6.4).
TYPE LOCATION: Sanders County, Montana; 2,100 feet west and 1,800 feet south of the NE corner of sec. 14, T. 21 N., R. 26 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 44 to 48 degrees F.
Moisture control section - between 8 to 24 inches.
Base saturation - 60 percent or less in one or more horizons between 10 and 30 inches from the soil surface
A horizon - Value: 4, 5, or 6 dry; 3, 4, or 5 moist
Clay content: 5 to 15 percent
Rock fragments: 15 to 30 percent--0 to 5 percent cobbles, 15 to 25 percent pebbles
Bulk density: .85 to 1 g/cc
Acid oxalate (Al + 1/2 Fe): 1.0 to 1.5 percent
Reaction: 5.6 to 7.3
Bw horizon - Value: 5 or 6 dry, 4 or 5 moist
Clay content: 5 to 15 percent
Rock fragments: 15 to 30 percent--0 to 5 percent cobbles, 15 to 25 percent pebbles
Bulk density: .85 to 1 g/cc
Acid oxalate (Al + 1/2 Fe): 1.0 to 1.5 percent
Reaction: 5.6 to 7.3
2E horizon - Value: 6 or 7 dry, 5 or 6 moist
Chroma: 2 or 3
Clay content: 8 to 15 percent
Rock fragments: 35 to 55 percent--5 to 15 percent cobbles, 30 to 40 percent pebbles
Reaction: 5.6 to 7.3
2E/Bw1 horizon - Value: E part 6, 7, or 8 dry, 5, 6 or 7 moist; B part 5, 6, or 7 dry, 4, 5, or 6 moist
Clay content: 8 to 15 percent
Rock fragments: 60 to 80 percent--5 to 20 percent cobbles, 55 to 60 percent pebbles
Reaction: 5.6 to 7.3
2E/Bw2 horizon - Value: E part 6, 7, or 8 dry, 5, 6 or 7 moist; B part 5, 6, or 7 dry, 4, 5, or 6 moist
Clay content: 5 to 15 percent
Rock fragments: 65 to 85 percent--10 to 15 percent cobbles, 55 to 70 percent pebbles
Reaction: 5.6 to 7.3
COMPETING SERIES:
Hoffstadt (WA) - has lithic contact of basalt at 40 to 60 inches; does not have an albic horizon.
Marblecreek (ID) - does not have an albic horizon.
Pearsoncreek (ID) - does not have an albic horizon or 2E/Bw horizons.
Sarazan (WA) - has lithic contact at 40 to 60 inches; does not have an albic horizon.
Tinker (CA) - does not have an albic horizon.
GEOGRAPHIC SETTING:
Landform - mountains; stream terraces.
Elevation - 3,400 to 3,900 feet.
Slope - 0 to 15 percent.
Parent material - glacial outwash.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 24 to 28 inches, much of which falls as snow and spring rains.
Mean annual temperature - 42 to 46 degrees F.
Frost-free period - 70 to 90 days.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained, moderate permeability.
USE AND VEGETATION: Backroad soils are used mainly for woodland, understory grazing, and wildlife habitat. Potential native vegetation is mainly ponderosa pine, Douglas fir, western larch, lodgepole pine, and grand fir. Understory vegetation is mainly common snowberry, white spirea, pinegrass, twinflower, and other forbs and shrubs.
DISTRIBUTION AND EXTENT: Backroad soils are of small extent in the mountains of northwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Sanders County, Montana, 1997.
REMARKS: Soil interpretations record: MT1388. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from 2 to 9 inches, mixed (A, Bw horizons); an ash influenced layer from 2 to 14 inches (A, Bw horizons); an albic horizon from 14 to 23 inches (2E horizon); a cambic horizon from 23 to 60 inches (2E/Bw1 and 2E/Bw2 horizons); a particle size control section from 10 to 40 inches below the mineral soil surface (Bw, 2E, 2E/Bw1, and 2E/Bw2 horizons). Backroad soils have a udic moisture regime and a frigid temperature regime.
ADDITIONAL DATA: NSSL S92MT-089-008