LOCATION MEADOWPASS MTEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, frigid Typic Argixerolls
TYPICAL PEDON: Meadowpass gravelly loam, rangeland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 3 inches; dark gray (10YR 4/1) gravelly loam, very dark gray (10YR 3/1) moist; weak fine and medium granular structure; soft, very friable, slightly sticky and slightly plastic, many very fine and fine and few medium and coarse roots; 15 percent gravel; slightly acid (pH 6.4); clear smooth boundary.
A2--3 to 9 inches; dark gray (10YR 4/1) gravelly loam, very dark gray (10YR 3/1) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine and few medium and coarse roots; few fine tubular pores; 15 percent gravel, 5 percent cobbles; slightly acid (pH 6.4); clear smooth boundary. (Combined A horizons - 7 to 12 inches thick)
Bt1--9 to 12 inches; brown (10YR 5/3) gravelly loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; soft, friable, slightly sticky and plastic; many very fine and fine and few medium roots; common fine tubular pores; few faint clay films on faces of peds; 15 percent gravel, 5 percent cobbles; slightly acid (pH 6.4); clear smooth boundary. (0 to 8 inches thick)
Bt2--12 to 18 inches; pale brown (10YR 6/3) sandy clay, brown (10YR 4/3) moist; weak coarse prismatic structure parting to strong medium angular blocky; hard, firm, sticky and very plastic; common very fine and fine and few medium roots; common very fine and fine interstitial and tubular pores; common prominent clay films on faces of peds and in pores; 10 percent gravel, 15 percent soft fragments; neutral (pH 6.8); gradual smooth boundary. (5 to 10 inches thick)
Bt/C--18 to 30 inches; B part (60 percent) is light olive brown (2.5Y 5/4) sandy clay, olive brown (2.5Y 4/4) moist; C part (40 percent) is pale yellow (2.5Y 7/4) sandy clay loam, light olive brown (2.5Y 5/4) moist; weak coarse prismatic structure; slightly hard, firm, sticky and very plastic; few very fine and fine roots along prism faces; few tubular and interstitial pores; common distinct clay films on faces of peds; 10 percent gravel, 40 percent soft fragments; neutral (pH 7.0); gradual smooth boundary. (4 to 15 inches thick)
Cr--30 inches; semi-consolidated welded tuff.
TYPE LOCATION: Sanders County, Montana; 2,900 feet east and 900 feet north of the SW corner of sec. 11, T. 24 N., R. 24 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 44 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 7 to 16 inches.
Depth to Cr horizon - 20 to 40 inches.
A horizons
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 1 or 2
Clay content: 15 to 27 percent
Rock fragments: 15 to 45 percent - 15 to 35 percent gravel; 0 to 10 percent cobbles
Reaction: pH 6.1 to 7.3
Bt1 horizon
Value: 5 or 6 dry; 3 or 4 moist
Chroma: 2 or 3
Clay content: 15 to 27
Rock fragments: 10 to 45 percent - 10 to 30 percent gravel; 0 to 5 percent cobbles; 0 to 10 percent soft fragments
Reaction: pH 6.1 to 7.3
Bt2 horizon
Hue: 10YR, 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 3 or 4
Texture: sandy clay, clay
Clay content: 35 to 60 percent
Rock fragments: 15 to 50 percent - 5 to 25 percent gravel; 10 to 25 percent soft fragments
Reaction: pH 6.1 to 7.3
Bt/C horizon
10YR, 2.5Y
Value: B part - 5 or 6 dry, 4 or 5 moist; C part - 6 or 7 dry, 5 or 6 moist
Chroma: B part - 3, 4 or 6; C part - 3 or 4
Texture: sandy clay, sandy clay loam
Clay content: 30 to 50 percent
Rock fragments: 10 to 70 percent - 5 to 25 percent gravel; 5 to 45 percent soft fragments
Reaction: pH 6.1 to 7.3
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform- hills.
Slope - 2 to 15 percent.
Elevation - 3,100 to 4,000 feet.
Parent material - colluvium and residuum derived from semi-consolidated welded tuff.
Climate - long, cold winters; moist springs; hot, dry summers.
Mean annual precipitation - 15 to 19 inches.
Mean annual temperature - 39 to 46 degrees F.
Frost-free season - 80 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS:
DRAINAGE AND PERMEABILITY: Well drained, slow permeability.
USE AND VEGETATION: Meadowpass soils are used as rangeland and pasture. Native vegetation is dominated by bluebunch wheatgrass, Idaho fescue, rough fescue, prairie junegrass and fringed sagewort.
DISTRIBUTION AND EXTENT: Meadowpass soils are of limited extent in the intermountain valleys of northwestern Montana. MLRA 43A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Sanders County, Montana, 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 12 inches (A1, A2, and Bt1 horizons);
Argillic horizon - 9 to 30 inches (Bt1, Bt2 and Bt/C horizons);
Paralithic contact - at a depth of 30 inches (Cr horizon);
Particle size control section - 9 to 29 inches (Bt1, Bt2 and Bt/C horizons).
Meadowpass soils have a frigid temperature regime and a xeric moisture regime.
Soil interpretations record MT1219.