LOCATION MODESS MTEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Aridic Haplustolls
TYPICAL PEDON: Modess sandy loam in rangeland (colors are for dry soil unless otherwise noted).
A1--0 to 5 inches; dark grayish brown (10YR 4/2) sandy loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and common fine and medium roots; 10 percent, mainly fine, gravel; moderately acid (pH 6.0); clear smooth boundary.
A2--5 to 11 inches; dark brown (10YR 3/3) gravelly sandy clay loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; slightly hard, friable, sticky and slightly plastic; common very fine and fine and few medium roots; few very fine and fine tubular pores; 20 percent, mainly fine, gravels; neutral (pH 6.8); clear wavy boundary. (Combined thickness of A horizons is 4 to 12 inches)
Bw--11 to 18 inches; yellowish brown (10YR 5/4) gravelly coarse sandy loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and few fine and medium roots; few very fine tubular pores; 20 percent, mainly fine, gravels; neutral (pH 7.0); abrupt wavy boundary. (4 to 16 inches thick)
Bk--18 to 30 inches; pale brown (10YR 6/3) gravelly coarse sandy loam, brown (10YR 5/3) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; 30 percent, mainly fine, gravels; disseminated lime; violently effervescent; moderately alkaline (pH 8.2); gradual wavy boundary. (6 to 24 inches thick)
BC--30 to 38 inches; light brownish gray (2.5Y 6/2) gravelly coarse sand, olive brown (2.5Y 4/3) moist; single grain; loose, loose, non-sticky and non-plastic; abundant very fine and few fine interstitial pores; 30 percent, mainly fine, gravels; slightly effervescent; moderately alkaline (pH 8.2); abrupt wavy boundary. (0 to 16 inches thick)
Cr--38 to 58 inches; soft, weathered granite bedrock.
R--58 inches; hard granite bedrock.
TYPE LOCATION: Silver Bow County, Montana; 500 feet north and 1,400 feet west of the SE corner of sec. 5, T. 4 N., R. 9 W. Ramsey topographic quadrangle, UTM zone 12T, 0365485E, 5108710N, NAD 27
RANGE IN CHARACTERISTICS:
Mean annual soil temperature 40 to 44 degrees F., frigid temperature regime.
Soil moisture control section 8 to 24 inches; dry more than six-tenths of the cumulative days per year when the soil temperature at a depth of 20 inches is at or above 41 degrees F. Ustic moisture regime bordering on aridic.
Thickness of mollic epipedon: 7 to 12 inches, mixed
Depth to secondary lime: 10 to 24 inches
Depth to Cr horizon: 20 to 40 inches
Depth to R horizon: 40 to 80 inches
Weighted average of clay in the particle-size control section: 10 to 18 percent
Rock fragment content in the particle-size control section: 15 to 35 percent
These soils contain a high proportion of medium, coarse, and very coarse angular sand in the sand fraction.
A Horizon
Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3
Texture: sandy loam, coarse sandy loam, sandy clay loam or loam
Clay content: 12 to 22 percent
Rock fragments: 5 to 50 percent--0 to 5 percent cobbles, stones and boulders, 5 to 45 percent, mainly fine, gravel
Reaction: pH 5.8 to 6.8
Bw Horizon
Hue: 10YR or 2.5Y
Value: 4, 5 or 6 dry; 3 or 4 moist
Chroma: 3 or 4
Texture: coarse sandy loam or sandy clay loam
Clay content: 14 to 24 percent
Rock fragments: 5 to 25 percent, mainly fine, gravel
Reaction: pH 6.6 to 7.8
Bk Horizon
Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 5 or 6 moist
Chroma: 2 or 3
Texture: coarse sandy loam or sandy loam
Clay content: 10 to 18 percent
Rock fragments: 10 to 30 percent, mainly fine, gravel
Calcium carbonate: 5 to 20 percent
Reaction: pH 7.8 to 8.4
BC Horizon
Hue: 2.5Y or 5Y
Value: 6 or 7 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: loamy coarse sand or coarse sand
Clay content: 2 to 8 percent
Rock fragments: 20 to 40 percent, mainly fine, gravel
Calcium carbonate: 0 to 2 percent
Reaction: pH 7.6 to 8.4
Note: This horizon may be absent in some profiles
COMPETING SERIES: These are the Anaconda, Chinook, Cozberg, Lahood, Pring, Rhame, Tinytown, and Ynot series. The Anaconda, Chinook, Cozberg, Pring, Tinytown and Ynot series are very deep. Lahood soils are moderately deep to a lithic contact and lack appreciable amounts of medium, coarse and very coarse sand. Rhame soils have less than 15 percent rock fragments in the particle-size control section and lack appreciable amounts of coarse and very coarse sand.
GEOGRAPHIC SETTING:
Landform- bedrock floored pediments and ridges in foothills and mountains
Elevation - 5,120 to 6,970 feet
Slope - 2 to 35 percent
Parent material - residuum from granite or other coarse grained igneous or metamorphic rocks
Climate - long cold winters; moist springs; warm, dry summers
Mean annual precipitation - 10 to 14 inches
Mean annual air temperature - 40 to 43 degrees F.
Frost-free period - 70 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS:
These are the Adit and Nuley series. Adit soils are very shallow to bedrock and occur mainly on convex knobs, ridges and shoulder slopes. Nuley soils are deep, have an argillic horizon and occur on more concave depositional positions.
DRAINAGE AND PERMEABILITY: well drained; moderate permeability.
USE AND VEGETATION: Modess soils are primarily used for rangeland and wildlife habitat. The native vegetation is mainly bluebunch wheatgrass, rubber rabbitbrush, silvery lupine, prairie junegrass, Cusick's bluegrass, fringed sagewort, horsebrush, and other miscellaneous forbs.
DISTRIBUTION AND EXTENT: Modess soils are of limited extent in foothills of southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Silver Bow County, Montana, 2007.
REMARKS: Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 11 inches (A1, A2 horizons); a cambic horizon from 11 to 18 inches (Bw horizon); a calcic horizon from 18 to 30 inches (Bk horizon); a paralithic contact at 38 inches (Cr horizon); a lithic contact at 58 inches (R horizon); a particle-size control section from 10 to 38 inches (A2, Bw, Bk, BC horizons). Modess soils have a frigid temperature regime and an ustic bordering on aridic moisture regime. Gravels throughout the profile are primarily fine pea gravel less than 7 mm in diameter.