LOCATION COALMONT CO+WYEstablished Series
TAXONOMIC CLASS: Fine, smectitic Ustic Argicryids
TYPICAL PEDON: Coalmont loam - grassland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 4 inches; light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; moderate very fine granular structure; soft, very friable, slightly sticky, slightly plastic; some of the sand grains have bleached surfaces; mildly alkaline (pH 7.6); abrupt smooth boundary. (3 to 6 inches thick)
B21t--4 to 10 inches; grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) moist; strong coarse prismatic structure that parts to coarse angular blocks; slightly hard, firm, very sticky, very plastic; peds are extremely hard, firm; thin continuous wax-like coatings on faces of peds, and wax-like coatings and fillings in root channels and pores; mildly alkaline (pH 7.6); clear wavy boundary. (5 to 17 inches thick)
B22t--10 to 16 inches; grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) moist; moderate coarse prismatic structure that parts to coarse angular blocks; hard, friable, sticky, plastic; peds are extremely hard, firm; thin nearly continuous wax-like coatings on faces of peds and wax-like coatings and fillings in root channels and pores; calcareous; moderately alkaline (pH 8.5); gradual wavy boundary. (0 to 8 inches thick)
B3ca--16 to 20 inches; light brownish gray (10YR 6/2) light clay, dark grayish brown (10YR 4/2) moist; weak coarse angular blocky structure; hard, friable, sticky, plastic; peds are extremely hard, firm; few thin glossy patches on faces of peds; discontinuous glossy coatings in root channels and pores; visible secondary calcium carbonate as concretions and in thin seams; calcareous; moderately alkaline (pH 8.5); diffuse wavy boundary. (3 to 6 inches thick)
C1ca--20 to 30 inches; light yellowish brown (2.5Y 6/3) clay loam, light olive brown (2.5Y 5/3) moist; massive; very hard, firm, sticky, plastic; visible secondary calcium carbonate as concretions and in thin seams and streaks; calcareous; moderately alkaline (pH 8.5); diffuse wavy boundary. (4 to 25 inches thick)
C2--30 to 60 inches; calcareous clay shale.
TYPE LOCATION: Jackson County, Colorado; 780 feet west and 780 feet north of SE corner of Sec. 19, T. 8 N., R. 79 W.
RANGE IN CHARACTERISTICS: Mean annual soil temperature is about 42 degrees F, and mean summer soil temperature is about 56 degrees F. Depth to uniformly calcareous material ranges from 7 to 30 inches. Depth to the paralithic contact ranges from 20 to 40 inches. Depth to the base of the argillic horizon ranges from 12 to 36 inches. Depth to continuous subhorizons of visible secondary carbonate and/or sulfate ranges from 10 to 36 inches, but such horizons are not strong enough to qualify as calcic or gypsic horizons. ESP either remains constant or increases with increasing depth, ranging from 0 to 15 percent in the solum but exceeding 15 percent in the Cca horizon in some pedons. Rock fragments range from 0 to 15 percent by volume in a major part of the solum and in the C horizon above the bedrock and are mainly 1/4 to 10 inches in diameter.
The A horizon has hue from 5Y through 7.5YR, value of 5 through 7 dry, 3 through 6 moist, and chroma of 1 through 4. It ranges from slightly acid to mildly alkaline.
The B2t horizon has hue of 5Y through 7.5YR, value of 5 through 7 dry, 4 through 6 moist, and chroma of 1 through 6. It is typically heavy clay loam or light clay but averages 35 to 50 percent clay, 15 to 40 percent silt, and 15 to 45 percent sand with more than 15 percent fine or coarser sand. This horizon ranges from slightly acid to moderately alkaline.
The C horizon, if present, has hue of 5Y through 7.5YR. Subhorizons redder than 7.5YR occur in some pedons. It is typically clay loam or clay but clay ranges from 18 to 50 percent. This horizon is moderately or strongly alkaline and has about 3 to 14 percent calcium carbonate equivalent of the fine earth fraction.
COMPETING SERIES: These are the Boettcher and Phillips series. Boettcher soils lack an abrupt textural change between the A and B2t horizons. Phillips soils lack a paralithic contact above a depth of 40 inches.
GEOGRAPHIC SETTING: Coalmont soils are on gently to moderately sloping upland hills and ridges where bedrock occurs above a depth of 40 inches. Slopes typically range from about 2 to 20 percent. The soil formed in medium to fine textured calcareous sediments weathered residually from sedimentary bedrock. At the type location the average annual precipitation is 10 inches with peak periods of precipitation in the spring and early summer. The average annual temperature is 38 degrees F, and the average summer temperature is 57 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Barishman soils and the competing Boettcher soils. Barishman soils lack a paralithic contact above a depth of 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; slow permeability.
USE AND VEGETATION: These soils are used principally as native pastureland. Native vegetation is mainly alkali sage, thickspike wheatgrass, and pine needlegrass.
DISTRIBUTION AND EXTENT: High mountain valleys of north-central Colorado. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jackson County, Colorado, 1973.
REMARKS: Last updated by the state 10/73.