LOCATION DAHLAKE MTTentative Series
TAXONOMIC CLASS: Fine-silty, mixed, active, calcareous, frigid Aeric Halaquepts
TYPICAL PEDON: Dahlake silt loam, rangeland (Colors are for moist soil unless otherwise noted.)
A--0 to 8 inches; very dark gray (2.5Y 3/1) silt loam, gray (2.5Y 6/1) dry; weak fine and medium granular structure; hard, firm, nonsticky and nonplastic; many very fine roots; strongly effervescent; strongly alkaline (pH 9.0); clear smooth boundary. (6 to 12 inches thick)
Bw--8 to 19 inches; light brownish gray (2.5Y 6/2) silt loam, light gray (5Y 7/2) dry; moderate medium prismatic structure parting to strong medium subangular blocky; hard, firm, slightly sticky and slightly plastic; few very fine roots; many very fine and fine interstitial and tubular pores; 60 percent distinct grayish brown (2.5Y 5/2) moist organic stains on all faces of peds; strongly effervescent; very strongly alkaline (pH 9.4); gradual smooth boundary. (5 to 18 inches thick)
BC--19 to 27 inches; light yellowish brown (2.5Y 6/3) silt loam, pale yellow (5Y 7/3) dry; moderate coarse prismatic structure parting to strong medium subangular blocky; hard, firm, nonsticky and nonplastic; few fine distinct yellowish brown (10YR 5/6) moist redox concentrations; few fine roots; common very fine and fine interstitial and tubular pores; 40 percent distinct grayish brown (2.5Y 5/2) moist organic stains on all faces of peds; strongly effervescent; very strongly alkaline (pH 9.4); gradual smooth boundary. (8 to 20 inches thick)
C--27 to 60 inches; light yellowish brown (2.5Y 6/3) silt loam, pale yellow (5Y 8/2) light yellowish brown dry; massive; hard, firm, nonsticky and nonplastic; common fine distinct yellowish brown (10YR 5/6) moist redox concentrations and common fine distinct gray (2.5Y 6/1) moist redox depletions; few very fine roots between peds; few tubular pores; strongly effervescent; very strongly alkaline (pH 9.6).
TYPE LOCATION: Flathead County, Montana; 1300 feet north and 400 feet west of the southeast corner of section 22, T. 28 N., R. 26 W. Dahl Lake topographic quadrangle. UTM zone 11: Northing 5337664, Easting 658251.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 42 to 45 degrees F.
Depth to seasonal high water table - 12 to 24 inches.
Clay content average in the particle-size control section - 18 to 27 percent.
A horizon
Hue - 2.5Y or 10YR
Value - 4 to 6 dry, 2 or 3 moist
Chroma - 1 or 2
Texture - silt loam
Clay content - 15 to 27 percent
Calcium carbonate equivalent - 5 to 15 percent
EC - 1 to 2 mmhos/cm
SAR - 6 to 30
Reaction - pH 8.4 to 9.6
Bw horizon
Hue - 2.5Y, 10YR, or 5Y
Value - 6 to 8 dry, 4 to 6 moist
Chroma - 1 or 2
Texture - silt loam or silty clay loam
Clay content - 18 to 35 percent
Calcium carbonate equivalent - 5 to 15 percent
EC - 2 to 4 mmhos/cm
SAR - 15 to 40
Reaction - pH 8.4 to 10.0
BC horizon
Hue - 5Y, 2.5Y or 5Y
Value - 6 to 8 dry, 4 to 6 moist
Chroma - 2 or 3
Texture - silt loam or very fine sandy loam
Clay content - 15 to 27 percent
Calcium carbonate equivalent - 5 to 15 percent
EC - 2 to 4 mmhos/cm
SAR - 13 to 35
Reaction - pH 8.4 to 10.0
C horizon
Hue - 2.5Y or 10YR
Value - 6 to 8 dry, 4 to 6 moist
Chroma - 2 or 3
Texture - silt loam or very fine sandy loam
Clay content - 15 to 27 percent
Rock fragments - 0 to 20 percent, 0 to 20 percent gravel
Calcium carbonate equivalent - 5 to 15 percent
EC - 1 to 4 mmhos/cm
SAR - 13 to 30
Reaction - pH 7.8 to 10.0
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Dahlake soils are on lake terraces in mountain valleys. Slopes range from 0 to 4 percent. These soils formed in mixed lacustrine sediments. Elevations range from 3,100 to 3,600 feet. The average annual air temperature ranges from 43 to 47 degrees F, average annual precipitation ranges from 15 to 21 inches, and the average frost-free period is from 70 to 100 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Whitebear(T), Meadowpeak, McLangor, and Barzee soils. Whitebear(T) soils are on lake terraces and alluvial fans and are coarse-silty. Meadowpeak, McLangor, and Barzee soils are on floodplains and closed depressions. Meadowpeak soils are coarse-silty and do not have cambic horizons. McLangor soils have a histic epipedon. Barzee soils consist of organic materials.
DRAINAGE AND PERMEABILITY: Poorly drained, moderately slow permeability.
USE AND VEGETATION: These soils are used for rangeland, wildlife habitat, and watershed. Potential natural vegetation is mainly Alkali cordgrass, Alkali sacaton, Nuttall's alkaligrass, Inland saltgrass, Alkali bluegrass, and Fowl bluegrass.
DISTRIBUTION AND EXTENT: Northwestern Montana. This soil is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Flathead County, Montana, 2003. The name is coined from Dahl Lake, in Flathead County, Montana.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 7 inches (A horizon)
Cambic horizon - the zone from 8 to 19 inches (A and Bw horizons)
Particle-size control section - the zone from 10 to 40 inches (Bw, BC, and C horizons)
Dahlake soils have an aquic moisture regime and a frigid temperature regime.
ADDITIONAL DATA: NSSL S97MT-029-001.