LOCATION WESTELK                 CO

Established Series
Rev. RHM, SJJ
11/2022

WESTELK SERIES

The Westelk series consists of moderately deep, well drained soils that formed in materials weathered from siltstone and silty shale. These soils are on moderate to steeply sloping upland hills, ridges, and mountainsides. The average annual precipitation at the Type Location is about 20 inches, and the mean annual air temperature is about 36 degrees F.

TAXONOMIC CLASS: Fine-silty, mixed, superactive Ustic Argicryolls

TYPICAL PEDON: Westelk silt loam - grassland. (Colors are for dry soil unless otherwise noted.)

A--0 to 8 inches; very dark grayish brown (10YR 3/2) silt loam, very dark brown (10YR 2/2) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; neutral; gradual smooth boundary. (6 to 12 inches thick)

Bt1--8 to 12 inches; dark grayish brown (10YR 4/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure, that parts to fine granular; slightly hard, very friable, slightly sticky and slightly plastic; few thin clay films on some peds; neutral; clear smooth boundary. (0 to 5 inches thick)

Bt2--12 to 24 inches; brown (10YR 5/3) silty clay loam, brown (10YR 4/3) moist; strong medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; peds are hard, very friable; thin nearly continuous clay films on ped faces, and in root channels and pores; neutral; gradual smooth boundary. (10 to 23 inches thick)

Cr--24 to 40 inches; soft noncalcareous silty shale and siltstone.

TYPE LOCATION: Gunnison County, Colorado; NE 1/4 Sec. 7, T. 15 S., R. 86 W.

RANGE IN CHARACTERISTICS: Westelk soils are noncalcareous throughout, except that in a few pedons very thin and discontinuous calcareous subhorizons occur just above the paralithic contact. In some pedons C horizons occur below the solum and above bedrock. Depth to the paralithic contact ranges from 20 to 40 inches. Depth to the base of the argillic horizon ranges from 15 to 40 inches. Rock fragments range from 0 to 35 percent by volume in a major part of the solum and C horizon, and range from 1/8 to 10 inches in diameter. The solum ranges from slightly acid through slightly alkaline. The mean annual soil temperature is 40 degrees F, and the mean summer soil temperature is 54 degrees F, without an O horizon present.

The A horizon has hue of 5Y through 7.5YR, value of 3 through 5 dry, 2 or 3 moist, and chroma of 1 through 3.

The Bt2 horizon has hue of 5Y through 7.5YR, value of 5 through 7 dry, 3 through 6 moist, and chroma of 1 through 6. It is typically silt loam, silty clay loam, or clay loam, with 18 to 35 percent clay, 35 to 65 percent silt, and 5 to 35 percent sand, and has less than 15 percent fine or coarser sand.

COMPETING SERIES: This is the Willow Creek series. Willow Creek soils are calcareous in the lower part of the solum and in the C horizon, have consistent horizons of secondary carbonate accumulation, and lack a paralithic contact above depth of 40 inches.

GEOGRAPHIC SETTING: The Westelk soils are on moderate to steeply sloping upland hills, ridges, and mountainsides. The soil formed in silty materials weathered from underlying siltstone and silty shale. At the Type Location the average annual precipitation is 20 inches, most of which falls during the spring and summer. The mean annual temperature is 36 degrees F, and mean summer temperature is 53 degrees F. Elevation is 9,000 to 10,000 feet.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Tongue River and Cochetopa soils. Tongue River soils lack mollic epipedons and have albic horizons. Cochetopa soils are fine textured and have mollic epipedons more than 16 inches thick.

DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderately slow permeability.

USE AND VEGETATION: These soils are used as native pastureland and for recreational purposes. Native vegetation is mainly Big sagebrush, Thurber fescue, Nodding brome, Idaho fescue, and scattered growths of aspen.

DISTRIBUTION AND EXTENT: High mountainous areas of central Colorado. The series is of moderate extent. MLRA 48A and 48B.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Gunnison County, Colorado, 1974.

REMARKS: Series was renamed on 11/2022, as instructed by National Headquarters, to remove offensive or sensitive names. Fine-silty particle size class would not be correct, if enough rock fragments 2mm to 3 inches (75mm) occur in the profile. This should be investigated.

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National Cooperative Soil Survey
U.S.A.