LOCATION COURVILLE MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Andic Eutrudepts
TYPICAL PEDON: Courville gravelly ashy silt loam, in coniferous forest (colors are for dry soil unless otherwise noted).
Oi--0 to 1 inch; undecomposed and slightly decomposed needles and twigs. (1 to 3 inches thick)
A--1 to 4 inches; dark grayish brown (10YR 4/2) gravelly ashy silt loam, black (10YR 2/1) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; 30 percent gravel; slightly acid (pH 6.1); clear smooth boundary. (0 to 3 inches thick)
Bw--4 to 14 inches; pale brown (10YR 6/3) gravelly ashy silt loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and slightly plastic; 25 percent gravel, 5 percent cobbles; slightly acid (pH 6.2); clear wavy boundary. (7 to 14 inches thick)
2E--14 to 33 inches; very pale brown (10YR 7/3) very gravelly sandy loam, brown (10YR 5/3) moist; massive; soft, nonsticky and nonplastic; 55 percent gravel, 5 percent cobbles; moderately acid (pH 6.0); clear wavy boundary. (10 to 24 inches thick)
2E/Bw--33 to 39 inches; E part (80 percent) is very pale brown (10YR 8/2) very gravelly sandy loam, light brownish gray (10YR 6/2) moist that surrounds the B part; B part (20 percent) is yellowish brown (10YR 5/4) very gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; massive; hard, friable, slightly sticky and slightly plastic; 45 percent gravel, 10 percent cobbles; moderately acid (pH 5.6); clear wavy boundary. (10 to 40 inches thick)
2Bw/E--39 to 60 inches; B part (75 percent) is yellowish brown (10YR 5/6) very gravelly sandy loam, dark yellowish brown (10YR 4/6) moist; E part (25 percent) is very pale brown (10YR 8/2) very gravelly sandy loam, light brownish gray (10YR 6/2) moist that surrounds the B part; massive; hard, friable, slightly sticky and slightly plastic; 45 percent gravel, 10 percent cobbles; moderately acid (pH 5.6).
TYPE LOCATION: Lake County, Montana; 600 feet south and 700 feet east of the NW corner of sec. 27, T. 22 N., R. 19 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 40 to 45 degrees F.
Moisture control section - approximately between the depths of 8 and 24 inches.
A horizon - Hue: 7.5YR or 10YR
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 1 or 2
Texture: ashy silt loam or ashy loam
Clay content: 7 to 15 percent
Rock fragments: 0 to 35 percent--0 to 20 percent cobbles and stones; 0 to 30 percent gravel
Bulk density: 1.0 grams per cubic centimeter or less
Acid oxalate Al + 1/2 Fe: 1 to 2 percent
Reaction: pH 5.6 to 6.5
Bw horizon - Hue: 7.5YR or 10YR
Value: 5 or 6 dry; 3 or 4 moist
Chroma: 3 or 4
Texture: ashy silt loam or ashy loam
Clay content: 7 to 15 percent
Rock fragments: 0 to 35 percent--0 to 20 percent cobbles and stones; 0 to 30 percent gravel
Bulk density: 1.0 grams per cubic centimeter or less
Acid oxalate Al + 1/2 Fe: 1 to 2 percent
Reaction: pH 5.6 to 6.5
2E horizon - Hue: 7.5YR or 10YR
Value: 6, 7, or 8 dry; 4, 5, or 6 moist
Chroma: 2 or 3
Texture: loam, sandy loam, fine sandy loam, or silt loam
Clay content: 5 to 18 percent
Rock fragments: 35 to 60 percent--0 to 20 percent cobbles and stones; 25 to 55 percent gravel
Reaction: pH 5.6 to 7.3
2E/Bw horizon - Hue: E part 7.5YR or 10YR; B part 7.5YR or 10YR
Value: E part 6, 7, or 8, B part 5 or 6 dry; E part 4, 5, or 6, B part 4 or 5 moist
Chroma: E part 2 or 3; B part 3 or 4
Texture: loam, silt loam, fine sandy loam, or sandy loam
Clay content: 10 to 25 percent
Rock fragment: 35 to 60 percent--0 to 20 percent cobbles and stones; 25 to 50 percent gravel
Reaction: pH 5.6 to 7.3
2Bw/E horizon - Hue: B part 7.5YR or 10YR; E part 7.5YR or 10YR
Value: B part 5 or 6, E part 6, 7, or 8 dry; B part 4 or 5, E part 4, 5, or 6 moist
Chroma: B part 3, 4 or 6; E part 2 or 3
Texture, mixed: loam, silt loam, fine sandy loam, or sandy loam
Clay content: 10 to 25 percent
Rock fragments: 35 to 60 percent--0 to 20 percent cobbles and stones; 25 to 50 percent gravel
Reaction: pH 5.6 to 7.3
COMPETING SERIES:
Bendahl (MT) - has horizons of secondary carbonate accumulation.
Mitten (MT) - has more than 60 percent rock fragments in the particle-size control section; has horizon containing lamellae.
GEOGRAPHIC SETTING:
Landform- foothills, moraines, and mountain slopes in glaciated valleys.
Elevation - 3,000 to 6,000 feet.
Slope - 2 to 60 percent.
Parent material - glacial till
Climate - long, cold winters, moist springs, warm summers.
Mean annual effective precipitation - 24 to 45 inches
Mean annual air temperature - 38 to 43 degrees F.
Frost-free period - 70 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS:
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Courville soils are used mainly for timber production, woodland grazing, and as wildlife habitat. The potential native vegetation is coniferous forest consisting mainly of grand fir, lodgepole pine, ponderosa pine, Engelmann spruce, Douglas-fir, western larch, western redcedar, and western hemlock with an understory of twinflower, beargrass, queencup beadlily, pachistima, arnica, and blue huckleberry.
DISTRIBUTION AND EXTENT: Courville soils are of moderate extent in northwestern Montana. MLRA 43A and 44A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Missoula County, Montana, 1985.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - from the mineral soil surface to 7 inches (A, Bw horizons);
Albic horizon - from 14 to 33 inches (2E horizon);
Cambic horizon - from 33 to 60 inches (2E/Bw, 2Bw/E horizons);
Particle-size control section - from 10 to 40 inches (Bw, 2E, 2E/Bw, 2Bw/E horizons).
Courville soils have a udic moisture regime and a frigid temperature regime.
Soil Interpretation Records: MT0419 and MT1116.