LOCATION NEBIES MTTentative Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Calcidic Argiustolls
TYPICAL PEDON: Nebies very cobbly loam, in grassland on a 2 percent neutral slope at 4,540 feet elevation. When described on May 18, 2000 the upper 18 inches of the profile was moist and the lower portion to 60 inches was dry (colors are for dry soil unless otherwise noted).
A--0 to 3 inches; very dark grayish brown (10YR 3/2) very cobbly loam, very dark brown (10YR 2/2) moist; strong very fine and fine granular structure; soft, very friable, slightly sticky, slightly plastic; common very fine, fine and medium roots; common very fine and fine interstitial and tubular pores; 15 percent gravel and 20 percent cobbles; neutral (pH 7.0); clear smooth boundary. (2 to 5 inches thick)
Bt--3 to 10 inches; brown (10YR 4/3) very cobbly clay loam, dark brown (10YR 3/3) moist; strong coarse subangular blocky structure parting to strong medium subangular blocky; slightly hard, friable, moderately sticky, moderately plastic; common very fine and fine roots; common very fine and fine interstitial and tubular pores; common discontinuous faint clay films on vertical faces of peds and on surfaces of pores; 20 percent gravel and 25 percent cobbles; neutral (pH 7.2); clear smooth boundary. (3 to 7 inches thick)
Bk1--10 to 18 inches; light brownish gray (10YR 6/2) very cobbly loam, grayish brown (10YR 5/2) moist; weak coarse subangular blocky structure parting to weak medium subangular blocky; soft, very friable, slightly sticky, slightly plastic; common very fine and fine roots; common very fine and fine interstitial and tubular pores; many medium distinct light gray (10YR 7/2) moist soft masses of lime in the matrix; many distinct light gray (10YR 7/2) moist carbonate coats on bottom surfaces of rock fragments; 20 percent gravel and 25 percent cobbles; violently effervescent; slightly alkaline (pH 7.6); clear wavy boundary. (4 to 12 inches thick)
Bk2--18 to 32 inches; light gray (10YR 7/2) very cobbly sandy loam, light brownish gray (10YR 6/2) moist; single grain; loose, nonsticky, nonplastic; common very fine roots; many medium distinct light gray (10YR 7/2) moist soft masses of lime in the matrix; many distinct light gray (10YR 7/2) moist carbonate coats on bottom surfaces of rock fragments; 20 percent gravel and 30 percent cobbles; violently effervescent; slightly alkaline (pH 7.8); clear wavy boundary. (14 to greater than 49 inches thick)
Bk3--32 to 60 inches; light gray (10YR 7/2) very cobbly coarse sandy loam, light brownish gray (10YR 6/2) moist; single grain; loose, nonsticky, nonplastic; common very fine roots; many fine distinct light gray (10YR 7/2) moist soft masses of lime in the matrix; many distinct light gray (10YR 7/2) moist carbonate coats on bottom surfaces of rock fragments; 20 percent gravel and 35 percent cobbles; violently effervescent; slightly alkaline (pH 7.6).
TYPE LOCATION: Park County, Montana; Elton topographic quadrangle; UTM zone 12T, 549613E, 5060135N, NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 45 to 47 degrees F.
Moisture control section - between 4 and 12 inches; dry in all parts between four-tenths and five tenths of the cumulative days per year when the soil temperature at 20 inches is 41 degrees F. or higher.
Mollic epipedon thickness - 7 to 12 inches.
Depth to argillic horizon 2 to 5 inches.
Depth to base of argillic 5 to 10 inches.
Depth to calcic horizon 5 to 10 inches.
Clay content 23 to 34 percent in the particle size control section.
Rock fragments - 35 to 60 percent in the particle size control section.
Soil phases stony and very stony, 15 to 60 percent cobbles are allowed on the surface.
A horizon:
Hue: 10YR
Value: 3 to 5 dry; 2 or 3 moist
Chroma: 2 or 3
Texture: Clay loam, loam or sandy loam
Clay content: 12 to 28 percent
Content of rock fragments: 20 to 60 percent15 to 25 percent gravel, 5 to 25 percent cobbles, 0 to 20 percent stones.
Electrical conductivity (dS/m): 0 to 0.5
Reaction: pH 6.6 to 7.8
Bt horizon:
Hue: 10YR
Value: 4 dry; 3 or 4 moist
Chroma: 2 or 3 dry; 2 to 4 moist
Texture: Clay loam, sandy clay loam or loam
Clay content: 23 to 34 percent
Content of rock fragments: 10 to 60 percent5 to 30 percent gravel, 5 to 40 percent cobbles, 0 to 20 percent stones.
Electrical conductivity (dS/m): 0 to 0.8
Reaction: pH 7.0 to 7.8
Bk horizons:
Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 5 to 7 moist
Chroma: 2 or 3 dry; 2 to 4 moist
Texture: Loam, sandy loam, loamy sand or coarse sandy loam
Clay content: 10 to 24 percent
Content of rock fragments: 35 to 60 percent20 to 45 percent gravel, 15 to 35 percent cobbles, 0 to 5 percent stones.
Electrical conductivity (dS/m): 0 to 0.3
Calcium carbonate equivalent: 10 to 35 percent
Reaction: pH 7.4 to 8.4
COMPETING SERIES:
Circleville (UT) - has a lithic contact at 20 to 36 inches.
Ipson (UT, WY) - are dry in parts of the moisture control section 75 to 90 days during the winter, and dry in all parts more than 40 percent of the time from April through October.
Sieben (MT) Depth to the base of the argillic is greater than 10 inches and depth to secondary carbonates is greater than 15 inches.
Uracca (CO) - does not have Bk horizons.
Widtsoe (UT) - has hue of 5YR or 7.5YR below the surface horizon.
GEOGRAPHIC SETTING:
Landscape Intermountain valleys.
Landform - Moraines, stream terraces, knobs or hills.
Elevation - 4,200 to 5,300 feet.
Slope - 0 to 35 percent.
Parent material - gravelly alluvium or gravelly till derived from igneous and/or metamorphic rock.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches.
Mean annual air temperature - 39 to 45 degrees F.
Frost-free period - 70 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Beaverell, Beavwan, Kremlin, Sixbeacon, Trimad and Vendome soils. The Beaverell soils have a sandy-skeletal substratum at depths of 10 to 20 inches and are on similar landform positions. The Beavwan soils are fine-loamy and are on similar landform positions. The Kremlin soils are fine-loamy and are on slightly higher convex to linear positions on the landform. Sixbeacon and Trimad soils do not have argillic horizons and are on slightly higher convex to linear positions on the landform. Vendome soils are sandy-skeletal and are on slightly higher convex to linear positions on the landform.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability in the upper part (A, Bt and Bk1 horizons) and moderately rapid permeability in the lower part (Bk2 and Bk3 horizons).
USE AND VEGETATION: Nebies soils are used mainly for rangeland and cropland. Potential native vegetation is mainly bluebunch wheatgrass, western wheatgrass, needleandthread, prairie Junegrass, thickspike wheatgrass, green needlegrass and blue grama.
DISTRIBUTION AND EXTENT: Nebies soils are of small extent in the intermountain valleys of southwestern Montana. MLRA 44.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES PROPOSED: Park County, Montana, 2003.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon the zone from the 0 to 10 inches (A and Bt horizons).
Argillic horizon the zone from 3 to 10 inches (Bt horizon).
Calcic horizon the zone from 10 to 32 inches (Bk1 and Bk2 horizons).
Horizons of secondary carbonate accumulations the zone from 10 to 60 inches (Bk1, Bk2 and Bk3 horizons).
Particle-size control section from 3 to 10 inches (Bt horizon).
Nebies soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.