LOCATION BEANLAKE MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Typic Calciustolls
TYPICAL PEDON: Beanlake stony loam, in native grassland (colors are for dry soil unless otherwise noted).
A--0 to 6 inches; dark grayish brown (10YR 4/2) stony loam, very dark grayish brown (10YR 3/2) moist; moderate very fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine roots; 10 percent pebbles, 3 percent stones; slightly alkaline (pH 7.8); clear smooth boundary. (5 to 8 inches thick)
Bk--6 to 16 inches; very pale brown (10YR 7/3) loam, brown (10YR 5/3) moist; weak medium prismatic structure parting to weak medium and fine subangular blocky; slightly hard, very friable, moderately sticky and slightly plastic; common very fine roots; many very fine tubular and interstitial pores; 5 percent pebbles, 5 percent cobbles; disseminated lime, common fine masses and seams of lime; continuous faint lime casts on undersides of fragments; violently effervescent; moderately alkaline (pH 8.4); gradual smooth boundary. (5 to 15 inches thick)
Bky1--16 to 38 inches; very pale brown (10YR 7/3) loam, brown (10YR 5/3) moist; weak medium and fine subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; common very fine roots; many very fine tubular and interstitial pores; 5 percent cobble-sized soft sandstone fragments, 5 percent pebbles, 5 percent cobbles; disseminated lime, common fine masses and seams of lime; continuous faint lime coatings and casts on undersides of fragments; common fine seams of gypsum; violently effervescent; common fine seams of gypsum; moderately alkaline (pH 8.4); gradual smooth boundary. (15 to 22 inches thick)
Bky2--38 to 60 inches; light gray (2.5Y 7/2) cobbly loam, brown (10YR 5/3) moist; weak medium and fine subangular blocky structure; hard, friable, moderately sticky and slightly plastic; few very fine roots; common very fine tubular and interstitial pores; 15 percent pebbles, 20 percent cobbles; disseminated lime, few fine masses and seams of lime; continuous faint lime casts on undersides of fragments; common fine seams and masses of gypsum; violently effervescent; strongly alkaline (pH 8.6).
TYPE LOCATION: Lewis and Clark County, Montana; 2,500 feet north and 2,200 feet east of the SW corner of sec. 19, T. 20 N., R. 7 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 7 to 8 inches.
The surface layer is calcareous when mixed to 7 inches.
A horizon - Hue: 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 1, 2 or 3
Texture: loam or silt loam
Clay content: 15 to 25 percent
Rock fragments: 10 to 30 percent--0 to 15 percent cobbles and stones, 0 to 15 percent pebbles
Reaction: pH 7.4 to 8.4
Bk horizon - Hue: 10YR
Value: 5, 6, 7, or 8 dry; 3, 4, 5, or 6 moist
Chroma: 2 or 3
Texture: loam or clay loam
Clay content: 18 to 30 percent
Calcium carbonate equivalent: 15 to 25 percent
Rock fragments: 10 to 35 percent--0 to 20 percent cobbles and stones, 5 to 15 percent pebbles
Reaction: pH 7.9 to 8.4
Bky1 horizon - Hue: 10YR or 2.5Y
Value: 7 or 8 dry, 5 or 6 moist
Chroma: 2 or 3
Texture: loam or clay loam
Clay content: 18 to 30 percent
EC: 0 to 4 mmhos/cm
Calcium carbonate equivalent: 15 to 35 percent
Gypsum content: 1 to 3 percent
Rock fragments: 10 to 35 percent--0 to 20 percent cobbles and stones, 5 to 15 percent pebbles
Reaction: pH 7.9 to 9.0
Bky2 horizon - Hue: 10YR or 2.5Y
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 2 or 3
Texture: loam or clay loam
Clay content: 18 to 30 percent
EC: 0 to 4 mmhos/cm
Gypsum content: 1 to 3 percent
Calcium carbonate equivalent: 8 to 15 percent
Rock fragments: 15 to 40 percent--0 to 5 percent stones, 10 to 20 percent cobbles, 5 to 15 percent pebbles
Reaction: pH 7.9 to 9.0
Bulk density of more than 1.6 grams per cubic centimeter.
COMPETING SERIES:
Ipano (MT) - lithic contact at a depth of 20 to 40 inches.
Kiev (MT) - moderate permeability and a bulk density of less than 1.6 grams per cubic centimeter, formed in alluvium.
Mudcree (UT) - paralithic contact at a depth of 20 to 40 inches.
Rabbitex (CO) - deeper than 8 inches to the calcic horizon, lithic contact at a depth of 40 to 60 inches.
Roundor (MT) - paralithic contact at a depth of 20 to 40 inches.
Zahl (ND) - has less than 10 percent coarse fragments in the particle-size control section; does not have horizon of gypsum accumulation.
GEOGRAPHIC SETTING:
Landforms - moraines, till plains, alluvial fans, stream terraces and escarpments.
Elevation - 3,800 to 6,000 feet.
Slope- 0 to 45 percent.
Parent material - till or alluvium.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 12 to 19 inches, most of which falls as snow in winter or as snow or rain early in spring and in summer.
Mean annual air temperature - 40 to 45 degrees F.
Frost-free period - 70 to 120 days.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Beanlake soils are used mainly for rangeland. Potential native vegetation is mainly rough fescue, bluebunch wheatgrass, Idaho fescue, Columbia needlegrass, prairie junegrass, forbs, and shrubs; some areas support thin stands of limber pine, Rocky Mountain juniper, and Douglas fir.
DISTRIBUTION AND EXTENT: Beanlake soils are inextensive in west-central Montana along the eastern front of the Rocky Mountains.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Choteau-Conrad Area, parts of Teton and Pondera Counties, Montana, 1991.
REMARKS: Soil interpretations record: MT0267, MT1320, MT1395. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the surface to 7 inches (mixed) (A horizon); calcic horizon from 6 to 38 inches (Bk and Bky1 horizons); horzons of gypsum accumulation from 16 to 60 inches (Bky1 and Bky2 horizons); particle-size control section from 10 to 40 inches (Bk, Bky1 and Bky2 horizons). Beanlake soils have a frigid temperature regime and an ustic moisture regime.