LOCATION ANTROBUS COEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Ustic Haplocryolls
TYPICAL PEDON: Antrobus very stony loam, grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 8 inches; dark grayish brown (10YR 4/2) very stony loam, very dark brown (10YR 2/2) moist; moderate medium granular structure; soft, very friable, slightly sticky, and slightly plastic; 40 percent basalt stones; many dark colored mineral grains in the sand and silt fractions; slightly effervescent; moderately alkaline; clear wavy boundary. (6 to 10 inches thick)
AC--8 to 13 inches; brown (7.5YR 5/2) very stony loam, dark brown (7.5YR 3/2) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky, and slightly plastic; 50 percent basalt stones; many dark colored mineral grains in the sand and silt fractions; strongly effervescent; moderately alkaline; diffuse wavy boundary. (4 to 10 inches thick)
C--13 to 60 inches; brown (7.5YR 5/2) extremely stony loam, brown (7.5YR 4/2) moist; massive; slightly hard, very friable, nonsticky, and nonplastic; 65 percent basalt stones; many dark colored mineral grains in the sand and silt fractions; strongly effervescent; moderately alkaline.
TYPE LOCATION: Garfield County, Colorado; 1,000 feet east and 2,300 feet north of the southwest corner of sec. 7, T. 7 S., R. 87 W.; Carbondale USGS quad; lat. 39 degrees 27 minutes 38 seconds N. and long. 107 degrees 09 minutes 24 seconds W., NAD 27.
RANGE IN CHARACTERISTICS: Thickness of the mollic epipedon ranges from 7 to 16 inches. These soils are generally calcareous throughout but are leached to depths of 1 or 2 inches in a few pedons. Organic carbon typically ranges from .8 to 2 percent and decreases uniformly with increasing depth. Rock fragments range from 35 to 80 percent and consist mainly of basalt fragments more than 10 inches in diameter. The particle size control section is very stony to extremely stony loam gravelly or very gravelly loam or clay loam and has 20 to 35 percent clay. Mean annual soil temperature ranges from 32 to 47 degrees F., and mean summer soil temperature ranges from 40 to 58 degrees F. without an 0 horizon.
The A horizon has hue of 2.5Y through 7.5YR, value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3. Primary structure is generally granular but may be subangular blocky. Consistence ranges from soft to slightly hard.
The C horizon has hue of 2.5Y through 7.5YR. Calcium carbonate equivalent ranges from less than 1 to about 4 percent.
COMPETING SERIES: These are the Brickel, Broad Canyon, Fairydell, Farlow, Foxmount (T), Grafen, Greyback, Handran, Kamack, Maurice, McCort (T), Midelight, Midfork, Parachute, Sebud, Silvercliff, Sup, Supervisor, Teemat (T), Thornburgh, Tiban, and Tineman series. Brickel, Foxmount, Grafen, Parachute, and Supervisor soils have a lithic or paralithic contact at depths of 20 to 40 inches. Broad Canyon, Handran, Maurice, McCort, Thornburgh, and Tineman soils contain less than 20 percent clay in the particle size control section. Greyback, Farlow, and Teeman soils have continuous horizons of secondary carbonate accumulation. Fairydell, Kamack, Sebud, and Tiban soils have cambic horizons. Midfork soils formed in material weathered from calcareous sedimentary rocks and lack dark colored minerial grains in the sand and silt fraction. Midelight soils formed in material weathered from metamorphic rocks. Sup soils are noncalcareous throughout with medium or slightly acid soil reactions. Silvercliff has a calcic horizon in the series control section.
GEOGRAPHIC SETTING: The Antrobus soils are on moderate to steeply sloping alluvial fans. Slope gradients typically range from 2 to 65 percent. The soils formed in thick very stony, medium to moderately fine textured parent sediments derived primarily from basalt. At the type location the average annual precipitation is 18 to 25 inches with near equal distribution throughout the year. The average annual temperature is 40 degrees F., the average summer temperature is 56 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cochetopa and Jerry soils. Cochetopa soils have mollic epipedons more than 16 inches in thickness. Jerry soils have an argillic horizon and have continuous horizons of secondary carbonate accumulation.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate permeability.
USE AND VEGETATION: These soils are used principally for grazing. Principal native vegetation is oakbrush, service berry, mountain mahogany, native bluegrass and wheatgrass.
DISTRIBUTION AND EXTENT: Western slope of the mountains in Colorado. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: The Aspen Gypsum Area, Colorado, 1982.