LOCATION COZDOME MTTentative Series
TAXONOMIC CLASS: Coarse-loamy over sandy or sandy-skeletal, mixed, superactive, frigid Aridic Haplustolls
TYPICAL PEDON: Cozdome sandy loam, in grassland on a 2 percent neutral slope at 4,910 feet elevation. When described on May 4, 1990 the upper 8 inches of the profile was slightly moist and the lower portion, 8 to 60 inches, was dry (colors are for dry soil unless otherwise indicated.)
A--0 to 3 inches; grayish brown (10YR 5/2) sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, nonsticky, nonplastic; many very fine and fine, and few medium roots; 3 percent gravel; neutral (pH 7.2); clear smooth boundary. (3 to 14 inches thick)
Bw--3 to 8 inches; grayish brown (10YR 5/2) sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; many very fine and fine, and few medium roots; 3 percent gravel; slightly alkaline (pH 7.4); clear smooth boundary. (0 to 20 inches thick)
Bk1--8 to 13 inches; light brownish gray (10YR 6/2) sandy loam, dark grayish brown (10YR 4/2) moist; weak coarse prismatic structure parting to weak medium subangular blocky; soft, very friable, slightly sticky, nonplastic; common very fine and fine roots; common 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; 3 percent cobbles and 7 percent gravel; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary.
Bk2--13 to 16 inches; light gray (10YR 7/2) gravelly sandy loam, grayish brown (10YR 5/2) moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; common very fine roots; common 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; 7 percent cobbles and 27 percent gravel; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (combined thickness of Bk horizons 0 to 8 inches)
2Bk3--16 to 60 inches; light brownish gray (10YR 6/2) extremely gravelly loamy sand, grayish brown (10YR 5/2) moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; common 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; 13 percent cobbles and 57 percent gravel; strongly effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Park County, Montana; 2,200 feet north and 1,600 feet west of the SE corner of section 23, T 5 S, R 8 E; Pray topographic quadrangle; UTM zone 12T, 523634E, 5025927N. NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 45 to 47 degrees F.
Moisture control section - between 4 and 12 inches; dry in some part for four-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 - 8 to 15 inches.
Depth to calcic horizon - 8 to 12 inches.
Depth to cambic horizon: (where present) - 4 to 14 inches.
Depth to Lithologic discontinuity (sandy-skeletal materials)- 10 to 26 inches.
Clay content less than 18 percent in the particle size control section.
A or Ap horizon(s):
Hue: 10YR
Value: 4 or 5 dry; 3 moist
Chroma: 2 or 3
Texture: Loam or sandy loam
Clay content: 8 to 18 percent
Content of rock fragments: 0 to 10 percent-- 0 to 10 percent gravel, 0 to 5 percent cobbles
Electrical conductivity (dS/m): 0 to 0.3
Reaction: pH 6.6 to 7.3
Bw horizon:
Hue: 10YR
Value: 5 dry; 3 or 4 moist
Chroma: 2 to 4
Texture: Loam or sandy loam
Clay content: 8 to 18 percent
Content of rock fragments: 0 to 10 percent--0 to 10 percent gravel, 0 to 5 percent cobbles
Electrical conductivity (dS/m): 0 to 0.3
Reaction: pH 6.6 to 7.6
Bk horizon(s):
Hue: 10YR
Value: 6 or 7 dry; 4 to 6 moist
Chroma: 2 to 4 dry; 2 or 3 moist
Texture: Loam or sandy loam
Clay content: 8 to 17 percent
Content of rock fragments: 0 to 35 percent--0 to 30 percent gravel, 0 to 10 percent cobbles
Calcium carbonate equivalent: 5 to 30 percent
Electrical conductivity (dS/m): 0 to 0.3
Reaction: pH 7.6 to 8.6
2Bk horizon:
Hue: 10YR
Value: 6 or 7 dry; 5 or 6 moist
Chroma: 2 to 4 dry; 2 or 3 moist
Texture: Loamy sand or sand
Clay content: 5 to 13 percent
Content of rock fragments: 50 to 85 percent40 to 80 percent gravel, 2 to 15 percent cobbles
Calcium carbonate equivalent: 5 to 30 percent
Electrical conductivity (dS/m): 0 to 0.3
Reaction: pH 7.6 to 8.6
2C horizon(s) (where present):
Hue: 10YR
Value: 6 dry; 5 moist
Chroma: 4
Texture: Loamy sand or sand
Clay content: 5 to 10 percent
Content of rock fragments: 40 to 70 percent10 to 60 percent gravel, 0 to 15 percent cobbles
Calcium carbonate equivalent: 0 to 25 percent
Electrical conductivity (dS/m): 0 to 0.3
Reaction: pH 7.4 to 8.4
Note: colors of this horizon are variegated in some pedons.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landscape Intermountain valleys.
Landform - Alluvial fans, stream terraces.
Elevation 4,200 to 5,400 feet.
Slope - 0 to 15 percent
Parent material - Coarse-loamy alluvium over gravelly alluvium 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 - 43 to 45 degrees F.
Frost-free period - 90 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Beaverell, Chinook, Cozberg and Vendome series. Beaverell soils are loamy-skeletal, have an argillic horizon and occur on slightly higher, more linear landform positions. Chinook and Cozberg soils are coarse-loamy and occur on similar landform positions. Vendome soils are sandy-skeletal and occur on slightly higher convex landform positions and stream terrace risers.
DRAINAGE AND PERMEABILITY: Well drained; moderately rapid permeability in the coarse-loamy material (A through Bk2 horizons) and rapid permeability in the sandy-skeletal material (2Bk3 horizon).
USE AND VEGETATION: Used mainly as rangeland and/or cropland. Potential native vegetation is bluebunch wheatgrass, needleandthread, blue grama and prairie Junegrass.
DISTRIBUTION AND EXTENT: Cozdome soils are of small extent in the intermountain valleys of southwestern Montana. MLRA44.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES PROPOSED: Park County, Montana, 2003.
REMARKS: Diagnostic features and horizons recognized in this pedon are:
Mollic epipedon the zone from the surface to 8 inches (A and Bw horizons).
Calcic horizon the zone from 8 to 60 inches (Bk1, Bk2 and 2Bk3 horizons)
Horizons of secondary carbonate accumulation the zone from 8 to 60 inches (Bk1, Bk2 and 2Bk3 horizons).
Particle-size control section the zone from 10 to 40 inches (Bk1, Bk2 and 2Bk3 horizons).
Cozdome soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.