LOCATION CUMBRES COEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Calcidic Argiustolls
TYPICAL PEDON: Cumbres stony loam - grassland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 4 inches; grayish brown (10YR 5/2) very stony loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable; 40 percent angular rock fragments (primarily basalt); neutral; clear smooth boundary. (2 to 6 inches thick)
B21t--4 to 7 inches; brown (10YR 5/3) very stony heavy clay loam; dark brown (10YR 3/3) moist; weak medium subangular blocky structure that parts to weak fine subangular blocks; slightly hard, very friable, slightly sticky and slightly plastic; 60 percent rock fragments, thin patchy clay films on peds; neutral; clear smooth boundary. (2 to 6 inches thick)
B22t--7 to 10 inches; brown (10YR 5/3) extremely stony heavy clay loam; dark brown (10YR 3/3) moist; weak medium subangular blocky structure that parts to weak fine subangular blocks; slightly hard, very friable, slightly sticky and slightly plastic; 60 percent rock fragments, thin patchy clay films on peds; neutral; clear smooth boundary. (2 to 6 inches thick)
B3--10 to 16 inches; light yellowish brown (10YR 6/4) extremely stony clay loam; dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure that parts to moderate fine subangular blocks; hard, friable, slightly sticky and slightly plastic; thin patchy clay films on peds; 70 percent lime-coated rocks; strongly effervescent, moderately alkaline; clear smooth boundary. (4 to 8 inches thick)
C1ca--16 to 22 inches; light gray (10YR 7/2) extremely stony sandy loam, grayish brown (10YR 5/2) moist; massive; hard, firm; 70 percent lime-coated rock fragments; very strongly effervescent with much disseminated lime and many lime nodules; moderately alkaline. (4 to 10 inches thick)
R--22 inches; basalt, fractured in some places.
TYPE LOCATION: Conejos County, Colorado; approximately 1,200 feet south and 950 feet east of the NW corner of Sec. 2, T. 33 N., R. 7 E.
RANGE IN CHARACTERISTICS: Depth to bedrock ranges from 20 to 40 inches. Rock fragments range from 20 to 40 percent by volume in the A horizon and 35 to 75 percent in the subsurface horizons, with 1/2 to 3/4 of total being 3 to 10 inches in diameter. Depth to uniformly calcareous material normally ranges from 7 to 24 inches. Depth to the base of the argillic horizon ranges from 8 to 24 inches.
The A horizon has hue of 7.5YR or 10YR, value of 4 or 5 dry, 2 or 3 moist, and chroma of 1 through 3.
B2t horizon has hue of 7.5YR through 2.5Y, value of 4 through 6 dry, 3 or 4 moist, and chroma of 2 through 4. Clay content of the fine earth fraction ranges from 35 to 45 percent.
The C horizon has hue of 7.5YR through 2.5Y.
COMPETING SERIES: These are the Radersburg series in the same family and the Borky series. Radersburg soils are more than 40 inches deep over bedrock. Borky soils have a paralithic contact at depths of 20 to 40 inches.
GEOGRAPHIC SETTING: The Cumbres soils are on hills and ridges and have gradients of 2 to 30 percent. The soils formed in material weathered from igneous rock. Elevation ranges from 8,000 to 9,300 feet. Average annual precipitation ranges from 14 to 16 inches. Mean annual temperature is 40 degrees F., mean summer temperature is 60 degrees F. The frost-free season is about 80 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Luhon, Stunner, and Travelers soils. Luhon and Stunner soils lack bedrock above a depth of 40 inches. Travelers soils have a loamy-skeletal control section.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used mainly for grazing land for sheep, cattle, and antelope. Native vegetation is dominantly blue grama, western wheat, yucca, prickly pear, rabbitbrush, scatter currant, some scattered pinyon, juniper, buckbrush and snowberry.
DISTRIBUTION AND EXTENT: Southwest part of the San Luis Valley, south- central Colorado. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Conejos County, Colorado, 1975.
REMARKS: Last updated by the state 7/57.