LOCATION VISION MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Typic Haplustalfs
TYPICAL PEDON: Vision gravelly loam, forested (colors are for dry soil unless otherwise noted).
Oi--0 to 1/2 inch; forest litter of partially decomposed twigs and needles.
A1--1/2 to 3 inches; dark grayish brown (10YR 4/2) gravelly loam, very dark brown (10YR 2/2) moist; weak fine platy structure parting to weak fine granular; soft, very friable, slightly sticky and slightly plastic; many fine and very fine roots; many very fine pores; 13 percent angular pebbles, 5 percent cobbles; slightly acid (pH 6.4); abrupt smooth boundary.
A2--3 to 7 inches; dark grayish brown (10YR 4/2) gravelly loam, very dark brown (10YR 2/2) moist; weak, medium, subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many fine roots, common medium roots; 20 percent angular pebbles, 5 percent angular cobbles; slightly acid (pH 6.4); clear wavy boundary. (The combined A horizons are 5 to 9 inches thick.)
Bt1--7 to 12 inches; grayish brown (10YR 5/2) gravelly loam, dark brown (10YR 4/2) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and medium roots; many fine and very fine tubular and interstitial pores; common faint dark brown (10YR 3/3) moist clay films on faces of peds; 25 percent angular pebbles, 5 percent angular cobbles; slightly acid (pH 6.4); gradual smooth boundary. (2 to 8 inches thick)
Bt2--12 to 20 inches; brown (10YR 5/3) very gravelly clay loam, dark brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common fine and medium roots; many fine and very fine tubular and interstitial pores; common distinct dark yellowish brown (10YR 4/4) moist clay films on faces of peds and lining pores; 35 percent angular pebbles and 5 percent angular cobbles; slightly acid (pH 6.4); clear smooth boundary.
Bt3--20 to 36 inches; very pale brown (10YR 7/2) very gravelly clay loam, brown (10YR 5/3) moist; moderate medium and coarse subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common fine and medium roots, few coarse roots; many fine and very fine tubular and interstitial pores; common distinct dark yellowish brown and yellowish brown (10YR 4/4 and 5/4) clay films on faces of peds and lining pores; 40 percent angular pebbles, 10 percent angular cobbles; slightly acid (pH 6.4); clear wavy boundary. (Combined thickness of Bt2 and Bt3 horizons is 20 to 40 inches)
BC--36 to 60 inches; very pale brown (10YR 7/3) extremely gravelly loam, yellowish brown (10YR 5/4) moist; weak medium and fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common medium roots, few coarse roots; many fine and very fine tubular and interstitial pores; common distinct dark yellowish brown (10YR 4/4) stains on coarse fragments; 45 percent angular pebbles, 15 percent angular cobbles, 5 percent angular stones; neutral (pH 6.6). (0 to 30 inches thick)
TYPE LOCATION: Sweet Grass County, Montana; 2,400 feet south and 250 feet west of the NW corner of sec. 19, T. 2 S., R. 16 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 40 to 45 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 5 to 9 inches. The mollic epipedon is too thin to classify as a Mollisol.
Depth to argillic horizon - 5 to 12 inches.
Coarse fragments - angular pebbles and cobbles of mixed rock origin.
A horizon - Value: 4 or 5 dry; 2 or 3 moist
Chroma: 1, 2, or 3
Clay content: 10 to 20 percent
Rock fragments: 15 to 35 percent--0 to 10 percent stones, 0 to 10 percent angular cobbles, 15 to 35 percent angular pebbles
Reaction: pH 5.6 to 7.3
Bt1 horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: clay loam, sandy clay loam or loam
Clay content: 20 to 30 percent
Rock fragments: 15 to 35 percent--0 to 5 percent stones, 5 to 10 percent angular cobbles, 10 to 25 percent angular pebbles
Base saturation: 75 to 100 percent
Reaction: pH 5.6 to 7.3
Bt2 and Bt3 horizons - Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: clay loam, sandy clay loam, loam, or silty clay loam
Clay content: 20 to 35 percent
Rock fragments: 35 to 60 percent--0 to 30 percent stones, 5 to 10 percent angular cobbles, 30 to 50 percent angular pebbles
Base saturation: 75 to 100 percent
Reaction: pH 5.6 to 7.3
BC horizon - Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: loam or sandy loam
Clay content: 10 to 27 percent
Rock fragments: 35 to 80 percent--5 to 10 percent angular stones, 10 to 20 percent angular cobbles, 20 to 50 percent angular gravels
Reaction: pH 5.6 to 7.3
COMPETING SERIES:
Abreu (NM) - has a lithic contact at 40 to 60 inches; has an E horizon 11 to 15 inches thick.
Amcec (NM) - has horizons of secondary carbonate accumulation.
Colomex (NM) - has a lithologic discontinuity in the argillic horizons.
Laventana (NM) - has an albic horizon.
Macmeal (MT) - has horizon of secondary carbonate accumulation.
Mocmont (MT) - has a glossic horizon.
Sheek (CO) - has soil moisture control section affected by peak periods of precipitation in July and August; has stones throughout the profile.
Skyview (MT) - has paralithic and lithic contacts at 20 to 40 inches.
Sonsela (NM) - is 60 inches or more to the base of the argillic horizon.
Trapps (MT) - has horizons of secondary carbonate accumulation.
Wahatoya (CO) - has a lithic contact at 20 to 40 inches.
Ymark (MT) - has paralithic and lithic contacts at 40 to 60 inches.
Yourame (MT) - has horizons of secondary carbonate accumulation.
Yreka (MT) - has a mixed E/Bt horizon.
GEOGRAPHIC SETTING:
Landform - mountains and hills, dominantly north aspects.
Elevation - 4,000 to 6,500 feet.
Slope - 15 to 60 percent.
Parent material - colluvium derived from igneous, argillite, metamorphic, and sedimentary rock.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 15 to 19 inches.
Mean annual temperature - 39 to 45 degrees F.
Frost-free period - 85 to 120 days.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: These soils are used mainly for grazeable woodland, wildlife, and timber products. Potential native vegetation is mainly Douglas-fir, ponderosa pine, Idaho fescue, mallow ninebark, pinegrass, snowberry, arnica, spirea, forbs, and low shrubs.
DISTRIBUTION AND EXTENT: Vision soils are of moderate extent in south central Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED Gallatin County, Montana, 1997; proposed in Sweet Grass County Area, Montana, 1993.
REMARKS: Soil interpretation records: MT1491. Diagnostic horizons and features recognized in this pedon are: has mollic colors from 1/2 to 7 inches (A1 and A2 horizons); an argillic horizon from 7 to 36 inches (Bt1, Bt2, Bt3, horizons); a particle-size control section from 7 to 27 inches (Bt1, Bt2, and part of Bt3 horizons). Vision soils have a frigid temperature regime and an ustic moisture regime.