LOCATION PRIMEN COEstablished Series
TAXONOMIC CLASS: Clayey, smectitic, mesic, shallow Aridic Argiustolls
TYPICAL PEDON: Primen cobbly clay loam on a convex, 30 to 50 percent side slopes in native grassland. (Colors are dry unless otherwise noted.)
A1--O to 4 inches; dark grayish brown (1OYR 4/2) cobbly clay loam, very dark grayish brown (1OYR 3/2) moist; weak fine granular structure; slightly hard, friable, sticky; 20 percent rock fragments; mildly alkaline; clear smooth boundary. (3 to 7 inches thick)
B1--4 to 9 inches; dark grayish brown (10YR 4/2) cobbly clay loam, very dark grayish brown (10YR 3/2) moist; weak coarse subangular blocky structure; hard, friable, sticky; few thin clay films on faces of peds; 25 percent rock fragments; mildly alkaline; clear smooth boundary. (0 to 6 inches thick)
B21t--9 to 14 inches; dark grayish brown (10YR 4/2) cobbly clay loam; very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; very hard, firm, sticky; common thin clay films on faces of peds; 25 percent rock fragments; mildly alkaline; clear wavy boundary. (3 to 6 inches thick)
B22t--14 to 18 inches; dark grayish brown (2.5Y 4/2) gravelly clay loam, dark grayish brown (2.5Y 4/2) moist, moderate medium subangular blocky structure; very hard, firm, sticky; few thin clay films on faces of peds; 15 percent rock fragments; mildly alkaline; gradual wavy boundary. (0 to 5 inches thick)
IICr--18 inches; light gray (2.5Y 7/2) soft sandstone, dark grayish brown (2.5Y 4/2) moist.
TYPE LOCATION: Jefferson County, Colorado; 1 3/4 miles north of the Denver Federal Center; 110 feet east and 1750 feet south of the northwest corner of Sec. 33, T. 3 S., R. 69 W.
RANGE IN CHARACTERISTICS: The mollic epipedon is 7 to 20 inches thick and in some pedons includes the upper part of the argillic horizon. Solum thickness and the depth to paralithic contact ranges from 10 to 20 inches. Rock fragments range from 15 to 35 percent by volume and are dominantly 1/8 to 10 inches in diameter. Some pedons are calcareous throughout with a calcium carbonate equivalent less than 15 percent. Mean annual soil temperature is less than 15 degrees F.
The A horizon has hue of 2.5Y through 7.5YR, value of 4 or 5, 2 or 3 moist, and chroma of 2 or 3. It has cobbly, very cobbly, very stony, or extremely stony modifiers of the fine earth fraction. Reaction is neutral to mildly alkaline.
The B horizon has hue of 2.5Y through 7.5YR, value of 4 through 6, 3 through 5 moist, and chroma of 2 through 4 with the darker colors in the upper part. It is gravelly clay loam, gravelly clay, cobbly clay loam, or cobbly clay and clay content ranges from 35 to 50 percent. Reaction is mildly to moderately alkaline.
IICr is soft shales, sandstones, and mudstones.
COMPETING SERIES: This is the Seligman series in the same family and the Shena series in another family. Seligman soils have a mean annual soil temperature of 52 to 58 degrees F. Shena soils have mixed mineralogy.
GEOGRAPHIC SETTING: Primen soils are on convex ridges and side slopes. Slopes range from 9 to 70 percent. They formed in clayey, gravelly, and cobbly materials overlying soft sedimentary rocks. Elevations range from 4,000 to 6,500 feet. They formed in a semiarid climate with average annual precipitation ranging from 13 to 17 inches. Mean annual temperature is 47 to 50 degrees F. Frost-free season is 125 to 145 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Denver, Kutch, Leyden, Nunn and Standley series. Denver, Nunn, and Standley soils lack bedrock above a depth of 60 inches. Kutch and Leyden soils have bedrock between a depth of 20 to 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; runoff is rapid; permeability is slow.
USE AND VEGETATION: Soils are used for grazing, recreation, wildlife habitat, and community development. Native vegetation is sideoats grama, needleandthread, western wheatgrass, green needlegrass, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Foothills and plains area of central Colorado. The series is of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jefferson County, Colorado, 1980. Golden Area Soil Survey.
REMARKS: Last updated by the state 4/80.