LOCATION BIGBEAVER MTEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, acid, frigid Aeric Fluvaquents
TYPICAL PEDON: Bigbeaver silt loam (colors are for moist soil unless otherwise noted).
A--0 to 4 inches; very dark grayish brown (10YR 3/2) silt loam, light brownish gray (10YR 6/2) dry; moderate fine granular structure; slightly hard, friable, nonsticky and nonplastic; many very fine and fine roots; very strongly acid (pH 5.0); clear smooth boundary. (2 to 9 inches thick)
C1--4 to 9 inches; very dark grayish brown (10YR 3/2) silt loam, light brownish gray (10YR 6/2) dry; moderate fine subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; many very fine and fine roots; few distinct yellowish brown (10YR 5/6) redox concentrations; very strongly acid (pH 5.0); clear smooth boundary. (3 to 10 inches thick)
C2--9 to 18 inches; brown (10YR 5/3) silt loam, light gray (10YR 7/2) dry; massive; slightly hard, friable, nonsticky and nonplastic; common very fine and fine roots; few distinct yellowish brown (10YR 5/6) redox concentrations; very strongly acid (pH 5.0); gradual wavy boundary. (5 to 14 inches thick)
C3--18 to 26 inches; brown (10YR 5/3) silt loam, light gray (10YR 7/2) dry; massive; slightly hard, friable, nonsticky and nonplastic; common very fine roots; common distinct yellowish brown (10YR 5/6) redox concentrations; very strongly acid (pH 5.0); gradual wavy boundary. (5 to 15 inches thick)
C4--26 to 36 inches; brown (10YR 5/3) silt loam, light gray (10YR 7/2) dry; massive; slightly hard, friable, nonsticky and nonplastic; few very fine roots; common distinct yellowish brown (10YR 5/6) redox concentrations; strongly acid (pH 5.2); gradual wavy boundary. (6 to 14 inches thick)
C5--36 to 60 inches; grayish brown (10YR 5/2) stratified silt loam, very fine sandy loam, and loam, light gray (10YR 7/2) dry; massive; slightly hard, friable, nonsticky and nonplastic; few very fine roots; common distinct yellowish brown (10YR 5/6) redox concentrations; strongly acid (pH 5.2).
TYPE LOCATION: Sanders County, Montana; 1800 feet west and 2100 feet south of the northeast corner of section 36, T. 23N., R. 31W.
RANGE IN CHARACTERISTICS:
Soil temperature - 44 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Depth to water table - 1.0 to 2.0 feet.
A horizon - Value: 5, 6, or 7 dry, 3, 4, or 5 moist
Clay content: 6 to 15 percent
Reaction: 4.5 to 5.5
C1 horizon - Value: 5, 6, or 7 dry, 3, 4, or 5 moist
Clay content: 6 to 15 percent
Reaction: 4.5 to 5.5
C2 horizon - Value: 6, 7 or 8 dry, 4, 5, 6 or 7 moist
Clay content: 6 to 15 percent; less than 15 percent fine sand or coarser
Reaction: 4.5 to 5.5
C3 horizon - Value: 6, 7 or 8 dry, 4, 5, 6 or 7 moist
Clay content: 6 to 15 percent; less than 15 percent fine sand or coarser
Reaction: 4.5 to 5.5
C4 horizon - Value: 6, 7 or 8 dry, 4, 5, 6 or 7 moist
Clay content: 6 to 15 percent; less than 15 percent fine sand or coarser
Reaction: 4.5 to 5.5
C5 horizon - Value: 6, 7 or 8 dry, 4, 5, 6 or 7 moist
Texture: stratified silt loam, loam, very fine sandy loam, fine sandy loam and loamy fine sand
Clay content: 6 to 15 percent
Reaction: 4.5 to 5.5
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - floodplains.
Elevation - 2200 to 2800 feet.
Slope- 0 to 2 percent.
Parent material - alluvium.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 28 to 34 inches.
Mean annual air temperature - 42 to 45 degrees F.
Frost-free period - 70 to 105 days.
DRAINAGE AND PERMEABILITY: Poorly drained, moderate permeability.
USE AND VEGETATION: Bigbeaver soils are used mainly for grazing and wildlife habitat. Potential native vegetation is mainly sedges, cinquefoil, timothy, reed canarygrass, black cottonwood, aspen, water birch, alder, Engelmann spruce, black hawthorn and redosier dogwood.
DISTRIBUTION AND EXTENT: Bigbeaver soils are of small extent in the valleys of northwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Sanders County, Montana 1997.
REMARKS: Soil Interpretation Record: MT1386. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches mixed (A, C1 horizons); stratified soil material from 36 to 60 inches (C5 horizon); a particle size control section from 10 to 40 inches (C2, C3, C4, and C5 horizons). Bigbeaver soils have an aquic moisture regime and a frigid temperature regime.
ADDITIONAL DATA: NSSL samples: S92MT-089-012, S93MT-089-006