LOCATION BIGLAKE MTEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, mixed, frigid Typic Haploxerolls
TYPICAL PEDON: Biglake gravelly sandy loam, in grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 9 inches; dark grayish brown (10YR 4/2) gravelly sandy loam, very dark brown (10YR 2/2) moist; moderate fine and medium granular structure; soft, very friable, nonsticky, and nonplastic; many very fine roots; many fine pores; 20 percent angular gravel; neutral (pH 6.8); clear wavy boundary. (6 to 12 inches thick)
Bw--9 to 16 inches; brown (10YR 5/3) very gravelly sandy loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; soft, very friable, nonsticky, and nonplastic; many fine and very fine roots; common fine pores; 40 percent angular gravel and 10 percent cobbles; neutral (pH 6.8); clear wavy boundary. (6 to 14 inches thick)
C--16 to 60 inches; light brownish gray (10YR 6/2) extremely gravelly loamy sand, brown (10YR 5/3) moist; single grain; loose, nonsticky, and nonplastic; few very fine roots in upper part; 55 percent angular gravel and 10 percent cobbles; neutral (pH 7.0).
TYPE LOCATION: Missoula County, Montana; 300 feet east and 2,000 feet north of the SW corner of sec. 12, T. 12 N., R. 20 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 43 to 47 degrees F.
Moisture control section - between 12 and 35 inches
Mollic epipedon thickness - 8 to 16 inches: may include the upper part of the Bw horizon
A horizon - Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3
Texture: loam or sandy loam
Clay content: 5 to 15 percent
Rock fragments: 15 to 35 percent--0 to 35 percent cobbles; 15 to 25 percent gravel
Reaction: pH 6.6 to 7.3
Bw horizons - Hue: 7.5 YR or 10YR
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 2 or 3
Clay content: 5 to 10 percent
Rock fragments: 35 to 60 percent--0 to 20 percent cobbles; 30 to 45 percent gravel
Reaction: pH 6.6 to 7.3
C horizon - Hue: 10YR or 7.5YR
Value: 6 or 7 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: loamy sand or sand
Clay content: 0 to 10 percent
Rock fragments: 60 to 80 percent--10 to 20 percent cobbles, stones; 45 to 60 percent gravel
Reaction: pH 6.6 to 7.3
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform- stream terraces, alluvial fans and hills.
Elevation - 2,500 to 4,500 feet.
Slope - 0 to 30 percent.
Parent material - alluvium or colluvium.
Climate - long cold winters, moist springs and falls, and warm dry summers.
Mean annual precipitation - 14 to 19 inches, much of which falls as snow and spring rain.
Mean annual temperature - 42 to 46 degrees F.
Frost-free period - 80 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS:
DRAINAGE AND PERMEABILITY: Excessively drained; moderately rapid permeability to a depth of 16 inches and rapid below.
USE AND VEGETATION: Biglake soils are used for rangeland and irrigated cropland. Potential native vegetation is mainly Idaho fescue, bluebunch wheatgrass, Sandberg bluegrass, prairie junegrass, forbs and shrubs.
DISTRIBUTION AND EXTENT: Biglake soils are of limited extent in mountain valleys in western Montana. MLRA 44A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Missoula County, Montana, 1985.
REMARKS: Soil Interpretation Records: MT1013. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from soil surface to 9 inches (A horizon); a cambic horizon from 9 to 16 inches (Bw horizon); a particle-size control section from 10 to 40 inches (Bw, C horizons). Biglake soils have a xeric moisture regime and a frigid temperature regime.