LOCATION SHEDHORN MTEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive Typic Haplocryolls
TYPICAL PEDON: Shedhorn clay loam, grassland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 4 inches; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; weak very fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine roots and common coarse roots; many very fine interstitial pores; 5 percent angular sandstone pebbles; slightly acid (pH 6.2); abrupt smooth boundary. (4 to 6 inches thick)
A2--4 to 12 inches; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; hard, friable, moderately sticky and moderately plastic; many very fine roots and common coarse roots; many very fine interstitial pores; 5 percent angular shale and sandstone pebbles; slightly acid (pH 6.2); clear smooth boundary. (8 to 10 inches thick)
Bw--12 to 40 inches; light brownish gray (2.5Y 6/2) light clay, grayish brown (2.5Y 5/2) moist; moderate fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common fine and very fine roots and few coarse roots; common fine and very fine interstitial pores; thin very dark grayish brown (2.5Y 3/2) moist organic coatings on faces of peds; 10 percent angular shale and sandstone pebbles; slightly acid (pH 6.5); clear smooth boundary. (28 to 32 inches thick)
BC--40 to 60 inches; dark grayish brown (2.5Y 4/2) clay loam, very dark grayish brown (2.5Y 3/2) moist; weak fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine, very fine, medium, and coarse roots; common fine and very fine interstitial pores; 30 percent angular shale pebbles.
TYPE LOCATION: Madison County, Montana; 2,200 feet north and 1,700 feet east of the SW corner of sec. 7, T. 8 S., R. 2 E.
RANGE IN CHARACTERISTICS:
Soil temperature:36 to 40 degrees F.
Mollic epipedon thickness:12 to 16 inches
A horizon:
Hue: 10YR or 2.5Y
Value, dry: 4 or 5
Value, moist: 3
Chroma: 1 or 2
Texture: clay loam or loam
Clay content: 27 to 35 percent
Rock fragments: 0 to 15 percent shale and sandstone fragments
Cobbles, angular: trace
Pebbles, angular: 0 to 15 percent
Reaction: pH 6.1 to 6.5
Bw horizon:
Hue: 10YR or 2.5Y
Value, dry: 5 or 6
Value, moist: 4 or 5
Chroma: 1 or 2
Texture: heavy clay loam or light clay
Clay content: 35 to 45 percent
Rock fragments: 5 to 35 percent shale and sandstone fragments
Cobbles, angular: 0 to 5 percent
Pebbles, angular: 5 to 30 percent
Reaction: pH 6.1 to 7.3
BC horizon:
Hue: 2.5Y or 5Y
Value, dry: 4, 5, or 6
Value, moist: 3, 4, or 5
Chroma: 2, 3, or 4
Texture: heavy clay loam or light clay
Clay content: 35 to 45 percent
Rock fragments: 10 to 35 percent, mainly shale fragments
Cobbles, angular: 0 to 5 percent
Pebbles, angular: 10 to 30 percent
Reaction: pH 6.1 to 7.8
NOTE: Colors are lithochromic, varying with the color of the parent material.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Shedhorn soils are on mountain slopes and glacial moraines. Elevations are 6,000 to 9,500 feet. Slopes are 0 to 70 percent. These soils formed under grass cover in colluvium and glacial till derived from consolidated shale and sandstone. The climate is cold. Mean annual precipitation is 25 to 50 inches. Mean annual temperature is 34 to 38 degrees F. The frost-free season is less than 70 days.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow permeability.
USE AND VEGETATION: Mainly used as rangeland and for wildlife habitat. The potential native vegetation is mainly bearded wheatgrass, mountain brome, basin wildrye, Columbia needlegrass, forbs, and shrubs. A few areas have tree cover consisting mainly of Douglas-fir.
DISTRIBUTION AND EXTENT: The high mountainous areas of southwestern Montana. This series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Madison County Area, Montana, 1983.