LOCATION CROW MTEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, frigid Typic Haplustalfs
TYPICAL PEDON: Crow silt loam, in coniferous forest (colors are for dry soil unless otherwise noted).
Oi--0 to 2 inches; undecomposed and slightly decomposed forest litter. (1 to 3 inches thick)
E1--2 to 3 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; strong very thin platy structure; soft, very friable, nonsticky and slightly plastic; many very fine, fine, medium, and coarse roots; many very fine and fine pores; 5 percent pebbles; moderately acid (pH 6.0); abrupt smooth boundary.
E2--3 to 6 inches; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; weak thin platy structure; slightly hard, firm, slightly sticky and plastic; many very fine, fine, medium, and coarse roots; many very fine pores; 10 percent pebbles; moderately acid (pH 5.8); abrupt smooth boundary. (The combined thickness of the E horizons is 3 to 10 inches)
Bt/E--6 to 12 inches; B part (75 percent) is yellowish brown (10YR 5/4) silty clay loam, brown (10YR 4/3) moist; E part (25 percent) is light brownish gray (10YR 6/2) silty clay loam, dark grayish brown (10YR 4/2) moist tongues; texture mixed is silty clay loam; strong medium subangular blocky structure; hard, firm, slightly sticky and plastic; many very fine, fine, medium, and coarse roots; many very fine pores; common distinct clay films on faces of peds and lining pores; 10 percent pebbles; moderately acid (pH 6.0); clear smooth boundary. (3 to 8 inches thick)
Bt1--12 to 37 inches; yellowish brown (10YR 5/4) silty clay, brown (10YR 4/3) moist; strong medium prismatic structure parting to moderate coarse subangular blocky; very hard, very firm, sticky and plastic; common very fine, fine, medium, and coarse roots; many very fine pores; many distinct clay films on faces of peds and lining pores; 10 percent pebbles; slightly acid (pH 6.2); clear smooth boundary. (10 to 30 inches thick)
Bt2--37 to 50 inches; yellowish brown (10YR 5/4) silty clay, dark yellowish brown (10YR 4/4) moist; strong medium prismatic structure parting to moderate medium angular blocky; very hard, very firm, sticky and plastic; few very fine and fine roots; common very fine pores; many prominent clay films on faces of peds and lining pores; 10 percent pebbles; slightly acid (pH 6.4); gradual smooth boundary. (5 to 15 inches thick)
BC--50 to 60 inches; very pale brown (10YR 7/4) sandy clay loam, yellowish brown (10YR 5/4) moist; moderate very fine angular blocky structure; slightly hard, firm, sticky and plastic; few very fine and fine roots; many very fine pores; many distinct clay films on faces of peds and lining pores; 10 percent pebbles; slightly acid (pH 6.4); gradual diffuse boundary.
TYPE LOCATION: Missoula County, Montana; 200 feet north and 100 feet east of the SW corner of sec. 12, T. 13 N., R. 15 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 40 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Control section - 35 to 60 percent clay.
Some pedons have a thin A horizon 1 to 4 inches thick, some pedons have an E/Bt horizon 2 to 4 inches thick.
E horizon - Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: loam, clay loam, or silt loam
Clay content: 10 to 35 percent
Rock fragments: 0 to 25 percent--0 to 5 percent cobbles, 0 to 25 percent pebbles
Reaction: pH 5.6 to 7.3
Bt/E horizon - Hue: 5YR, 7.5YR, 10YR or 2.5Y
Value: B part 5 or 6, E part 6, 7, or 8 dry; B part 4 or 5, E part 5 or 6 moist
Chroma: B part 2, 3, or 4; E part 2 or 3
Texture, mixed: silty clay loam, clay loam, loam, or silt loam
Clay content, mixed: 20 to 40 percent
Rock fragments: 0 to 25 percent--0 to 5 percent cobbles, 0 to 25 percent pebbles
Reaction: pH 5.6 to 7.3
Bt1 and Bt2 horizon - Hue: 2.5YR, 5YR, 7.5YR, 10YR or 2.5Y
Value: 4, 5, or 6 dry; 4 or 5 moist
Chroma: 2, 3, 4, or 6
Texture: silty clay, clay, sandy clay, clay loam, or silty clay loam
Clay content: 35 to 60 percent
Rock fragments: 0 to 35 percent--0 to 10 percent cobbles, 0 to 25 percent pebbles
Reaction: pH 6.1 to 7.3
BC horizon - Hue: 2.5Y, 10YR, or 7.5YR
Value: 6 or 7 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4
Texture: sandy clay loam, clay loam, loam, or sandy loam
Clay content: 15 to 35 percent
Rock fragments: 5 to 35 percent--0 to 10 percent cobbles, 5 to 25 percent pebbles
Reaction: pH 6.1 to 7.8
COMPETING SERIES:
Dargol (NM) moderately deep to a lithic contact.
Heckly (NM) moderately deep to a lithic contact.
Ligocki (NM) has horizons of secondary carbonate accumulation.
Lubrecht (MT) moderately deep to a paralithic contact.
Rittel (MT) moderately deep to a paralithic contact.
Valnor (NM) moderately deep to a paralithic contact.
Zuni (NM) moderately deep to a lithic contact.
GEOGRAPHIC SETTING:
Landform - alluvial fans; stream terraces; mountains; hills; glacial moraines.
Elevation - 3,500 to 6,500 feet.
Slope - 0 to 60 percent.
Parent material - colluvium and till from Tertiary age sediment.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 16 to 30 inches, much of which falls as snow and spring rain.
Mean annual temperature - 38 to 45 degrees F.
Frost-free period - 70 to 105 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Lubrecht soils and the Bignell and Shooflin soils. Bignell soils are clayey-skeletal. Shooflin soils are very fine.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Crow soils are used for production of timber, woodland, wildlife habitat, and for grazing. The native vegetation is coniferous forest consisting mainly of ponderosa pine, western larch, and Douglas fir with an understory of common snowberry, pinegrass, and dwarf huckleberry.
DISTRIBUTION AND EXTENT: Crow soils are of small extent in western Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Lake County, Montana, 1929.
REMARKS: Soil interpretation records: MT0563. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 6 inches (Oi, E1 and E2 horizons); albic horizons from 2 to 6 inches (E1 and E2 horizons); an argillic horizon from a depth of 6 to 50 inches (Bt/E, Bt1 and Bt2 horizons); a particle-size control section that is the upper 20 inches of the argillic horizon from 6 to 26 inches (Bt/E and part of the Bt1 horizon). Crow soils have a frigid temperature regime and an ustic moisture regime that borders on udic.