LOCATION VELDKAMP COEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, mixed, superactive, mesic Aridic Argiustolls
TYPICAL PEDON: Veldkamp very cobbly sandy loam - grassland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 3 inches; dark grayish brown (10YR 4/2) very cobbly sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; slightly hard, friable, slightly sticky; 35 to 50 percent rock fragments dominantly gravel and cobbles; neutral; clear smooth boundary. (2 to 8 inches thick)
B21t--3 to 6 inches; dark grayish brown (10YR 4/2) very cobbly clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure parting to moderate medium granular; hard, firm, sticky; few thin clay films on faces of some peds and coating rock fragments; 35 to 50 percent rock fragments; neutral; clear smooth boundary. (2 to 8 inches thick)
B22t--6 to 12 inches; brown to dark brown (10YR 4/3) very cobbly clay, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure parting to moderate fine subangular blocky; hard, firm, very sticky; common moderately thick clay films on faces of peds and coating rock fragments; 35 to 50 percent rock fragments; neutral; clear smooth boundary. (4 to 10 inches thick)
B23t--12 to 21 inches; dark yellowish brown (10YR 4/4) very cobbly heavy clay loam, dark yellowish brown (10YR 3/4) moist; moderate medium subangular blocky structure parting to moderate fine subangular blocky; hard, firm, sticky; few thin clay films on the faces of peds and coating rock fragments; 35 to 50 percent rock fragments; neutral; clear wavy boundary. (6 to 14 inches thick)
2C--21 to 60 inches; dark yellowish brown (10YR 4/4) stratified very cobbly sandy loam, dark yellowish brown (10YR 3/4) moist; massive; slightly hard, friable, slightly sticky; 35 to 50 percent rock fragments; neutral.
TYPE LOCATION: Jefferson County, Colorado; about 6 miles north of Golden; 105 feet north and 100 feet west of the southeast corner of Sec. 2, T. 3 S., R. 70 W.
RANGE IN CHARACTERISTICS: The mollic epipedon ranges from 7 to 20 inches thick. The thickness of solum ranges from 15 to 30 inches. The clay content of the fine earth fraction of the B2t ranges from 35 to 60 percent. Rock fragments range from 35 to 60 percent by volume and are most commonly well rounded and are dominantly 1/8 to 10 inch in diameter. Reaction is neutral to mildly alkaline.
The A horizon has hue of 7.5YR through 2.5Y, color value of 3 through 5, 2 or 3 moist, and chroma of 2 or 3. It has cobbly and very cobbly modifiers.
The B2t horizon has hue of 7.5YR through 2.5Y, color value of 4 through 6, 2 through 5 moist and chroma of 2 through 4. It is dominantly very gravelly and very cobbly clay loam, clay and sandy clay.
The 2C horizon has hue of 7.5YR through 2.5Y. It is stratified and most commonly very gravelly and very cobbly sandy clay loam and sandy loams.
COMPETING SERIES: These are the Stroupe and Tafoya series. Stroupe soils have a lithic contact at a depth of 20 to 40 inches and the Tafoya soils have sola over 30 inches thick. Both soils have a higher percentage by volume of stones.
GEOGRAPHIC SETTING: Veldkamp soils are on pediments; high terraces and side slopes. Slopes range from 0 to 5 percent. Elevations range from 5,600 to 6,500 feet. The soils formed in very gravelly and cobbly stratified old alluvium derived from sedimentary, metamorphic and igneous rocks. The average annual precipitation ranges from 16 to 18 inches. The mean annual temperature is about 47 degrees F. The frost free season is 125 to 142 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Flatirons, Nederland, Willowman, and Valmont soils. Flatirons soils have an abrupt increase in clay content from the A to B2t horizons. The Nederland and Willowman soils have B2t horizons with less than 35 percent clay. Valmont soils have contrasting substratums.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; slow permeability.
USE AND VEGETATION: Soils are used for grazing, wildlife, and community development. Native vegetation is mainly blue grama, little bluestem, mountain muhly, switch grass, big bluestem, western wheatgrass, and forbs.
DISTRIBUTION AND EXTENT: Foothills area of north central Colorado. The series is of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Golden Area Soil Survey, Jefferson County, Colorado, 1980.
REMARKS: Last updated by the state 4/80.
The superactive cation exchange activity class was added in 03/2003 to the taxonomic classification by the National Soil Survey Center on request of the Lakewood MLRA office, without review of the soil series property data. The remainder of this document has not been updated.