LOCATION SHAAK MT+WYEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Vertic Paleustolls
TYPICAL PEDON: Shaak silty clay loam - native grass. (Colors are for dry soil unless otherwise noted.)
A2--0 to 4 inches; light brownish gray (10YR 6/2) silt loam, dark brown (10YR 3/3) moist; weak thin platy structure beneath a soft vesicular surface crust; soft, very friable, nonsticky and nonplastic; many very fine roots; continuous coating of clear unstained mineral grains on peds; neutral (pH 7.0); abrupt smooth boundary. (2 to 5 inches thick)
B and A--4 to 6 inches; grayish brown (10YR 5/2) silty clay loam, dark brown (10YR 3/3) moist; moderate medium prismatic structure that parts to moderate medium and thick platy and fine angular blocky; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; patchy dark grayish brown (10YR 4/2) clay films and nearly continuous coating of clear unstained mineral grains; neutral (pH 7.0); clear wavy boundary. (2 to 4 inches thick)
B2t--6 to 15 inches; brown (10YR 5/3) clay, dark brown (10YR 4/3) moist; moderate medium prismatic structure in upper part parting to strong fine and very fine angular blocky; strong medium prismatic structure in lower part parting to moderate medium angular blocky; very hard, firm, very sticky and very plastic; common very fine roots; common fine and very fine tubular pores; continuous brown (10YR 4/2) clay films on peds and bridging and coating sand grains throughout peds; few clear sand grains on surfaces of peds; 5 percent pebbles; mildly alkaline (pH 7.0); gradual smooth boundary. (6 to 16 inches thick)
B3t--15 to 18 inches; light yellowish brown (2.5Y 6/4) silty clay, dark brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate medium and fine angular blocky; very hard, firm, very sticky and very plastic; common very fine roots; common fine and very fine pores; discontinuous brown (10YR 5/3) very thin clay films; slightly effervescent; moderately alkaline (pH 8.0); clear irregular boundary. (2 to 6 inches thick)
C1ca--18 to 44 inches; light brownish gray (2.5Y 6/2) light silty clay, light olive brown (2.5Y 5/4) moist; weak medium prismatic structure in upper part that parts to medium angular blocky, weak coarse blocky structure in lower part; very hard, firm, sticky and plastic; common very fine roots; common fine and very fine pores; 10 percent pebbles; few to common soft nodules of segregated lime; strongly effervescent; moderately alkaline (pH 8.3); clear boundary.
IIC2--44 to 60 inches; pale brown (10YR 6/3) very gravelly loam, brown (10YR 5/3) moist; massive; hard, friable, nonsticky and nonplastic; 50 percent pebbles; strongly effervescent; moderately alkaline (pH 8.3).
TYPE LOCATION: Yellowstone County, Montana; 660 feet east and 475 feet south of W1/4 corner, section 9, T.4S., R.27E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 41 to 47 degrees F. Depth to calcareous material ranges from 12 to 24 inches. Depth to very gravelly or extremely gravelly IIC horizon is 24 to 50 inches. Coarse fragments in the A and B horizons range from 0 to 10 percent pebbles. The B3 horizon and upper part of the C horizon have 0 to 20 percent pebbles; and the IIC horizon has 35 to 60 percent pebbles. Some pedons have brown (10YR 5/3) loam or silt loam A1 horizons. The B3cs and C1ca horizons have 5 to 15 percent calcium carbonate.
The A horizon has hue of 7.5YR or 10YR, value of 5 or 6 dry, 4 or 5 moist, and chroma of 2 or 3. It is mainly loam or silt loam. Some cultivated areas are silty clay loam, or clay loam. This horizon is slightly acid or neutral.
The B horizon has hue of 7.5YR through 2.5Y, value of 4 or 5 dry, 3 or 4 moist, and chroma of 2 through 4. It averages silty clay or clay. This horizon is neutral or mildly alkaline. Some pedons contain a B3ca horizon.
The C horizon has hue of 10YR or 2.5Y, value of 5 or 6 dry, 4 or 5 moist, and chroma of 2 or 3. The upper part of the C horizon in some pedons is silty clay, clay, or gravelly clay loam. The IIC horizon is very gravelly clay loam, very gravelly loam or very gravelly sandy loam. The C horizon is mildly or moderately alkaline.
COMPETING SERIES: These are the Coben and Ekah series in the same family and the related Dutton and Shane series. Coben soils have a gray-capped columnar B2t horizon and have a Ccs horizon. Dutton soils have soft bedrock at depths of 20 to 40 inches. Ekah soils have a calcic horizon. Shane soils are very-fine.
GEOGRAPHIC SETTING: Shaak soils are nearly level to gently sloping and are on terraces and fans at elevations of 3,000 to 4,500 feet. They formed in loamy alluvium from mixed rock origin. The climate is cool semiarid, continental, with cold dry winters and moist springs. The mean annual temperature ranges from 41 to 47 degrees F. The average annual precipitation ranges from 13 to 17 inches, most of which falls during spring and early summer. The (32 degrees F.) growing season is 105 to 125 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Danvers, Farland, Gerdrum, and Oburn soils. All of these soils may occur in complex with Shaak soils on the same landscape. Danvers and Farland soils lack an abrupt clay textural increase in the B2t horizon. Gerdrum and Oburn soils have natric horizons.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; slow permeability.
USE AND VEGETATION: Dryland production of small grains and as rangeland. Principal native vegetation is western wheatgrass, blue grama, Sandberg bluegrass and fringed sagewort.
DISTRIBUTION AND EXTENT: Eastern Montana and Wyoming near the high mountain ranges. Shaak series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Big Horn County (Big Horn Area), Montana, 1970.
OSED scanned by SSQA. Last revised by state on 11/76.