LOCATION SILAS WY+CO OR UTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Cumulic Haplocryolls
TYPICAL PEDON: Silas loam-rangeland. (Colors are for dry soil unless otherwise stated.)
A1--0 to 3 inches; very dark gray (10YR 3/1) loam, black (10YR 2/1) moist; weak very fine crumb structure; soft, very friable, slightly sticky and nonplastic; many very fine medium and coarse roots; few pebbles and cobbles; neutral (pH 6.8); abrupt smooth boundary. (1 to 10 inches thick)
A2--3 to 22 inches; very dark grayish brown (10YR 3/2) loam, very dark brown (10YR 2/2) moist with thin lenses of black (10YR 2/1) and very dark gray (10YR 3/1); massive; soft, very friable, slightly sticky and nonplastic; many very fine and medium coarse roots; few pebbles and cobbles; neutral (pH 6.9); abrupt wavy boundary. (10 to 20 inches thick)
C--22 to 60 inches; brown (10YR 5/3) loam stratified with thin lenses of very fine sandy loam, silt loam, dark brown (10YR 4/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; 10 percent gravel, 5 percent cobbles; neutral (pH 7.0).
TYPE LOCATION: Fremont County, Wyoming; SW1/4, SW1/4 of sec. 4, T. 30 N., R. 99 W.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is about 40 to 44 degrees F., and the mean summer soil temperature is about 50 to 55 degrees F. The organic carbon content ranges from 1 to 5 percent and decreases irregularly with depth. The 10- to 40-inch control section is loam or clay loam stratified with lenses of very fine sandy loam and silt loam. It averages 18 to 35 percent clay. Rock fragments range from 0 to 15 percent and are cobbles or gravel. These soils are noncalcareous throughout. Some pedons have strata of sand and gravel below 40 inches.
The A horizon has hue of 2.5Y or 10YR, value of 3 through 5 dry, 2 or 3 moist, and chroma of 1 through 3. Reaction is slightly acid through mildly alkaline.
The C horizon has hue of 2.5Y through 7.5YR, value of 4 through 6 dry, 3 or 4 moist, and chroma of 1 through 4. Reaction is slightly acid through mildly alkaline.
COMPETING SERIES: This is the Adderton series. The Adderton soils are well drained. Leavittville, Osmund, Thayne, and Uhl soils are similar. Leavittville and Osmund soils have a regular decrease in organic carbon. The Thayne and Uhl soils do not have the thick mollic epipedon.
GEOGRAPHIC SETTING: Silas soils are on mountain valley fills and outwash terraces. Slopes are 0 to 12 percent. The soils formed in mixed alluvium. Elevation is 7,000 to over 11,000 feet. The mean annual precipitation is about 12 to 25 inches. Where mean annual precipitation is less than 15 inches, additional moisture in the form of snowpack or runon from surrounding areas is available. The mean annual temperature is about 32 to 44 degrees F., and the mean summer temperature is about 50 to 57 degrees F. The frost-free season is estimated to range from 60 to 90 days, but frost may occur at any time in higher elevations.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ansel, Farlow, and Midelight soils. Ansel soils formed under conifer cover and have an argillic horizon. Farlow and Midelight soils lack the thick mollic epipedon.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow to medium runoff; moderately permeable.
USE AND VEGETATION: These soils are mainly used for range. Some areas are used for pasture and hay production. Native vegetation is bluegrass, sedges, quaking aspen, rose bushes, and forbs.
DISTRIBUTION AND EXTENT: In the mountainous areas of Wyoming and Colorado. The soil is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Fremont County, Wyoming, Lander Area; 1975.
REMARKS: Diagnostic horizons recognized in this pedon are:
Mollic epipedon--0 to 22 inches (A1,A2)