LOCATION GREYBEAR MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Aridic Haplustolls
TYPICAL PEDON: Greybear clay loam, rangeland (colors are for dry soil unless otherwise noted).
A--0 to 2 inches; brown (7.5YR 5/2) clay loam, dark brown (7.5YR 3/2) moist; weak medium granular structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine, fine and medium roots; many fine and very fine pores; slightly effervescent; neutral (pH 7.2); abrupt smooth boundary. (2 to 7 inches thick)
Bw--2 to 8 inches; brown (7.5YR 4/2) clay loam, dark brown (7.5YR 3/2) moist; weak fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; many very fine and fine pores; strongly effervescent; slightly alkaline (pH 7.8); gradual wavy boundary. (5 to 12 inches thick)
Bk1--8 to 22 inches; reddish gray (5YR 5/2) clay loam, dark reddish gray (5YR 4/2) moist; strong medium and coarse prismatic structure; very hard, firm, very sticky and very plastic; common very fine and fine roots; common very fine and fine pores; common fine and medium masses and threads of segregated lime; violently effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (4 to 16 inches thick)
Bk2--22 to 35 inches; dark reddish gray (5YR 4/2) clay loam, dark reddish brown (5YR 3/2) moist; moderate medium angular blocky structure; very hard, friable, very sticky and very plastic; few very fine and fine roots; common very fine and fine pores; common fine soft masses and threads of segregated lime; violently effervescent; strongly alkaline (pH 8.6); gradual wavy boundary. (4 to 15 inches thick)
Bk3--35 to 56 inches; dark reddish gray (5YR 4/2) gravelly clay loam, dark reddish brown (5YR 3/2) moist; weak medium angular blocky structure; very hard, very firm, very sticky and very plastic; few very fine roots; few very fine and fine pores; 15 percent pebbles; few fine soft masses of segregated lime; strongly effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (0 to 24 inches thick)
Cr--56 to 60 inches; dark gray (5YR 4/1) stratified semiconsolidated shale and siltstone sedimentary beds, very dark gray (5YR 3/1) moist; slightly effervescent.
TYPE LOCATION: Sweet Grass County, Montana; 850 feet west and 1900 feet south of the northeast corner of section 27, T.1 N., R.13 E.; Latitude - 45 degrees, 48 minutes, 31 seconds North; Longtitude - 110 degrees, 5 minutes, 16 seconds West.
RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 46 degrees F.
Moisture control section - between 4 and 12 inches; dry in some part for six tenths or more of the cumulative days per year when the soil temperature at a depth of 20 inches is higher than 41 degrees F.
Mollic epipedon thickness - 7 to 12 inches.
Depth to Bk horizon - 8 to 20 inches.
Depth to Cr horizon - 40 to 60 inches.
A horizon - Hue: 10YR, 7.5YR, or 5YR
Chroma - 2 or 3
Texture: clay loam, silty clay loam, silty clay or clay
Clay content: 27 to 50 percent
Rock fragments: 0 to 5 percent pebbles
Reaction: pH 6.6 to 7.8
Bw horizon - Hue: 7.5YR, 5YR, or 2.5YR
Value: 4, 5 or 6 dry; 3, 4 or 5 moist
Chroma: 2 or 3
Texture: clay loam, silty clay loam or silty clay
Clay content: 35 to 45 percent
Rock fragments: 0 to 5 percent pebbles
Reaction: pH 7.4 to 9.0
Bk1, Bk2 horizons - Hue: 7.5YR, 5YR, or 2.5YR
Value: 4, 5, or 6 dry; 3, 4, or 5 moist
Chroma: 2 or 3
Texture: clay loam, silty clay loam or silty clay
Clay content: 35 to 45 percent
Rock fragments: 0 to 5 percent pebbles
Calcium Carbonate Equivalent: 5 to 15 percent
Reaction: pH 7.9 to 9.0
Note: Color values of 5 dry and 3 moist with low chroma are lithochromic.
Bk3 horizon - Hue: 7.5YR, 5YR, or 2.5YR
Value: 4, 5, or 6 dry; 3, 4, or 5 moist
Chroma: 2 or 3
Texture: clay loam, silty clay loam or silty clay
Clay content: 35 to 45 percent
Rock fragments: 5 to 25 percent pebbles
Calcium Carbonate Equivalent: 5 to 15 percent
Reaction: pH 7.9 to 9.0
Note: Color values of 5 dry and 3 moist with low chroma are lithochromic.
COMPETING SERIES:
There are no competing series.
GEOGRAPHIC SETTING:
Landform - sedimentary plains, depressions and intermontane basins.
Elevation - 3,500 to 5,500 feet.
Slope - 0 to 15 percent.
Parent material - clayey alluvium over shale and siltstone residuum
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches.
Mean annual temperature - 39 to 45 degrees F.
Frost-free period - 90 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Greybear soils are used mainly for dryland and irrigated cropland, pasture, and rangeland. Potential native vegetation is mainly western wheatgrass, green needlegrass, bluebunch wheatgrass, blue grama, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Greybear soils are of small extent in south central Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Sweet Grass County, Montana, 2000.
REMARKS: Soil Interpretations Records: MT1538. Diagnostic
horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 8 inches (Ap, Bw horizon); horizons of secondary carbonate accumulation from 8 to 56 inches (Bk horizons); a particle-size control section from 10 to 40 inches (Bk1, Bk2, Bk3 horizons); a paralithic contact at 56 inches (Cr horizon). Greybear soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.