LOCATION SNEFFELS           WY
Established Series
Rev. PSD
02/1999

SNEFFELS SERIES


The Sneffels series consists of well drained soils that are moderately deep to hard sandstone. They are on ridges, dip slopes, and mountain slopes. The Sneffels soils formed in slope alluvium and residuum derived from sedimentary bedrock. Slopes are 2 to 20 percent. The mean annual precipitation is about 17 inches, and the mean annual temperature is about 35 degrees F.

TAXONOMIC CLASS: Fine, smectitic Ustic Argicryolls

TYPICAL PEDON: Sneffels loam-rangeland. (Colors are for dry soil unless otherwise stated.)

A1--0 to 3 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, friable, slightly sticky and slightly plastic; many fine roots; neutral (pH 7.2); clear smooth boundary.

A2--3 to 11 inches; dark brown (10YR 4/3) loam, dark brown (10YR 3/3) moist; moderate fine and medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; neutral (pH 7.2); clear smooth boundary. (Combined thickness of the A horizon is 3 to 11 inches)

Bt1--11 to 17 inches; brown (10YR 5/3) clay loam, dark brown (10YR 4/3) moist; moderate fine and medium prismatic structure parting to moderate medium angular blocky; hard, firm, sticky and plastic; common fine roots; many thin and few moderately thick clay films on faces of peds; mildly alkaline (pH 7.4); clear smooth boundary.

Bt2--17 to 27 inches; yellowish brown (10YR 5/4) clay, dark yellowish brown (10YR 4/4) moist; moderate medium prismatic structure parting to strong fine and medium angular blocky; hard, firm, sticky and plastic; few fine roots; common thick clay films on faces of peds; mildly alkaline (pH 7.4); abrupt smooth boundary. (Combined thickness of the Bt horizon is 10 to 25 inches)

R--27 inches; hard, noncalcareous sandstone fractured in the upper few inches but not displaced.

TYPE LOCATION: Natrona County, Wyoming; SE1/4, NW1/4 of sec. 36, T. 32 N., R. 79 W.

RANGE IN CHARACTERISTICS: The mollic epipedon ranges from 7 to 15 inches thick and includes the upper part of the argillic horizon in about half the observed pedons. Depth to bedrock ranges from 20 to 40 inches. Where bedrock depth exceeds 30 inches, a BC or C horizon is common. The mean annual soil temperature is about 34 to 40 degrees F., and the mean summer temperature is 50 to 56 degrees F. These soils are noncalcareous throughout.

The A horizon has hue of 7.5YR or 10YR, value of 3 or 4 dry, 2 or 3 moist, and chroma of 2 or 3. Coarse fragments, mainly pebbles or channers, range from 0 to 15 percent. Clay ranges from 20 to 27 percent. It is slightly acid or neutral.

The Bt horizon has hue of 3 through 5 dry, 3 or 4 moist, and chroma of 2 through 4. Texture is heavy clay loam or clay with 35 to 50 percent clay. It may be modified with 0 to 15 percent pebbles or channers and 0 to 5 percent cobbles or flagstone. It is slightly acid through mildly alkaline.

COMPETING SERIES: These are the Brinkert, Buckskin, Florissant, Gothic, Heath, Jerry, Judy, Little Horn, Mayoworth, Owen Creek, Piltz, Sessions, Trout Creek, Waters, and Youman series. The Brinkert, Buckskin, Gothic, Heath, Jerry, Sessions, and Youman soils are deep. The Florissant soils have a contact to a Bkm at 20 to 40 inches. Judy and Little Horn soils have horizons of carbonate accumulation. Mayoworth, Owen Creek, Piltz, and Trout Creek soils have a paralithic contact at 20 to 40 inches. Waters soils have hue of 5YR or redder.

GEOGRAPHIC SETTING: Sneffels soils occur on ridges, dip slopes, and mountain slopes. They formed in slope alluvium and residuum derived primarily from argillaceous sandstone. Slopes are 2 to 20 percent. Elevations range from 7,000 to 8,500 feet or more. The mean annual precipitation ranges from 15 to 23 inches. The mean annual temperature is about 33 to 36 degrees F. The frost-free season is estimated to range from 45 to 75 days but some south aspects may reach 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chittum and competing Owen Creek soils. The Chittum soils have bedrock at less than 20 inches.

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

USE AND VEGETATION: Rangeland and wildlife habitat. Native vegetation consists of Idaho fescue, bluebunch wheatgrass, prairie junegrass, low rabbitbrush, winterfat, and big sagebrush.

DISTRIBUTION AND EXTENT: Mountain areas of Wyoming and Colorado. The series is of limited extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Natrona County Area, Wyoming; 1985.

National Cooperative Soil Survey
U.S.A.


REMARKS: The Sneffels series was proposed in Colorado in 1972 but was never correlated at the type location. The concept of the soils fits soils mapped in Natrona County, Wyoming, and the series was established during the final correlation conference of Natrona County in 1985. The type location has been moved from Colorado to Wyoming.