LOCATION CHAMA ND+MTEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Typic Calciustolls
TYPICAL PEDON: Chama silt loam on an 8 percent south-southeast-facing slope in a pasture. When described, the soil was dry throughout. (Colors are for dry soil unless otherwise stated.)
A--0 to 4 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium and fine subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; neutral; abrupt smooth boundary. (3 to 7 inches thick)
Bw--4 to 8 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; slightly hard, friable, slightly sticky and nonplastic; slight effervescence; slightly alkaline; clear smooth boundary. (0 to 7 inches thick)
Bk1--8 to 13 inches; light gray (2.5Y 7/2) silt loam, light olive brown (2.5Y 5/4) moist; weak medium prismatic structure parting to moderate medium and fine subangular blocky; slightly hard, friable, slightly sticky and nonplastic; many fine masses of carbonates; violent effervescence; slightly alkaline; clear smooth boundary.
Bk2--13 to 22 inches; light yellowish brown (2.5Y 6/4) silt loam, olive brown (2.5Y 4/4) moist; weak medium subangular blocky and weak thick platy structure; slightly hard, friable, slightly sticky and nonplastic; many medium masses of carbonates; violent effervescence; slightly alkaline; clear smooth boundary. (Combined Bk horizons 0 to 28 inches thick)
BCk--22 to 34 inches; light yellowish brown (2.5Y 6/4) silt loam, light olive brown (2.5Y 5/4) moist; massive; slightly hard, friable, slightly sticky and nonplastic; many large carbonate concretions; slight effervescence; slightly alkaline; gradual wavy boundary. (0 to 14 inches thick)
Cr--34 to 60 inches; pale yellow (2.5Y 7/4) soft siltstone, light olive brown (2.5Y 5/4) moist; slight effervescence; slightly alkaline.
TYPE LOCATION: Slope County, North Dakota; 1420 feet east and 1180 feet north of the southwest corner, sec. 15, T. 136 N., R. 99 W.
RANGE IN CHARACTERISTICS: Depth to soft bedrock ranges from 20 to 40 inches. The mollic epipedon ranges from 7 to 10 inches thick.
The A horizon has hue of 10YR or 2.5Y, value of 3 to 5 and 2 or 3 moist, and chroma of 2. It is silt loam, silty clay loam, clay loam or loam. It is neutral to moderately alkaline.
The Bw horizon has hue of 2.5Y or 10YR, value of 4 to 7 and 3 to 6 moist, and chroma of 2 or 3. It is silt loam or silty clay loam. It is calcareous throughout and is slightly alkaline or moderately alkaline.
The Bk horizon has hue of 10YR, 2.5Y or 5Y, value of 4 to 7 and 3 to 6 moist, and chroma of 2 to 4. It is silt loam or silty clay loam. It is slightly alkaline to strongly alkaline.
Some pedons have a C horizon above the Cr horizon.
COMPETING SERIES: There are the Maschetah and Rusklyn series. These soils do not have paralithic beds at depths of 20 to 40 inches.
GEOGRAPHIC SETTING: Chama soils are on level to very steep uplands. Slope gradients are commonly 3 to 15 percent but range from 0 to 45 percent. The soils formed in materials weathered from soft siltstone, mudstone and shale. The mean annual air temperature is 39 to 45 degrees F, and the mean annual precipitation is 13 to 18 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cabba, Golva, Grassna, Morton, Reeder and Sen soils. Cabba soils are on knobs and steeper landscapes. They have soft bedrock at depths of less than 20 inches. Golva and Grassna soils are in the lower lying positions. They do not have soft siltstone within 40 inches. Morton and Reeder soils are on similar positions. They have argillic horizons. Sen soils are on similar landscapes. They have noncalcareous Bw horizons.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium to rapid. Permeability is moderate or moderately slow.
USE AND VEGETATION: Soils are cropped to small grains, which are mostly wheat; a significant acreage is in rangeland. The native vegetation is principally western wheatgrass, needleandthread and blue grama.
DISTRIBUTION AND EXTENT: Western North Dakota, eastern Montana, and possibly northwestern South Dakota. The series is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Wibaux County, Montana, 1956.
REMARKS: Revised 5/94.
Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 8 inches; calcic horizon - the zone from 8 to 22 inches (Bk1 and Bk2 horizons).