LOCATION RED ROCK UTEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Cumulic Haploxerolls
TYPICAL PEDON: Red Rock silt loam - dry cropland (Colors are for dry soil unless otherwise noted.)
Ap--0 to 9 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium and coarse subangular blocky structure; soft, friable, nonsticky, slightly plastic; common fine roots; many fine pores; slightly alkaline (pH 7.7); abrupt smooth boundary. (6 to 13 inches thick)
A--9 to 17 inches; grayish brown (10YR 5/2) silt loam, very dark brown (10YR 2/2) moist; weak medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common fine roots; common fine pores; slightly alkaline (pH 7.4); clear smooth boundary. (8 to 20 inches thick)
Bw1--17 to 25 inches; grayish brown (10YR 5/2) silt loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; hard, friable, slightly sticky, slightly plastic; common fine roots; common fine pores; neutral (pH 7.3); clear smooth boundary. (0 to 10 inches thick)
Bw2--25 to 37 inches; grayish brown (10YR 5/2) silt loam, dark brown (10YR 3/3) moist, moderate medium subangular blocky structure; hard, friable, slightly sticky, slightly plastic; common fine roots; common fine and medium pores; neutral (pH 7.3); gradual wavy boundary. (6 to 18 inches thick)
Bw3--37 to 48 inches; light brownish gray (10YR 6/2) silt loam, dark brown (10YR 3/3) moist; weak medium and coarse subangular blocky structure; hard, friable, slightly sticky, slightly plastic; few fine roots; few fine and few medium pores; moderately calcareous; slightly alkaline (pH 7.4); gradual wavy boundary. (9 to 14 inches thick)
Bk1--48 to 66 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; massive; hard, friable, slightly sticky, slightly plastic; few fine roots; few fine pores; moderately calcareous, lime is laminar and veined; slightly alkaline (pH 7.7); gradual wavy boundary. (O to 25 inches thick)
C--66 to 84 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; massive; hard, friable, slightly sticky, slightly plastic; few fine roots; moderately calcareous, lime is non-indurated and massive; slightly alkaline (pH 7.8).
TYPE LOCATION: Box Elder County, Utah; about 1/2 mile northwest of Blue Creek exit from Interstate 80 in Blue Creek Valley; 1,500 feet north and 1,300 feet west of SE corner, sec. 1, T.13N., R.6W.
RANGE IN CHARACTERISTICS: The average annual soil temperature at 20 inches is 47 to 55 F., and the average summer temperature is 68 to 74 F. The soil is usually moist. It is moist in some part of the moisture control section for more than one-half of the time the soil temperature is above 41 degrees F. in 7 out of 10 years. The soils is dry in all parts of the moisture control section for 60 to 90 consecutive days following the summer solstice.
The mollic epipedon is 20 to 48 or more inches thick. Organic matter content decreases irregularly or remains above 0.5 percent to a depth of 50 inches. The series control section averages about 18 to 27 percent clay and contains less than 15 percent coarser than very fine sand. Base saturation percentage is about 85 to 100.
The A horizon has value of 4 or 5 dry and 2 or 3 moist and chroma of 1 to 3. It is neutral to slightly alkaline. This horizon is dominantly noncalcareous but some recharging of lime has occurred in the surface plow layer in some pedons making it slightly calcareous.
The B horizon has value of 5 or 6 dry, and 2 through 4 moist and chroma of 2 or 3. It is loam, silt loam or silty clay loam. This horizon is neutral to moderately alkaline and is noncalcareous.
The Bk and C horizons have hue of 10YR or 2.5Y, value of 5 or 6 dry, and 3 to 5 moist, and chroma of 2 through 4. It ranges from fine sandy loam to clay loam and is stratified at depths below 36 inches in some pedons. This horizon is slightly to strongly alkaline and slightly to moderately calcareous, with less than 15 percent calcium carbonate equivalent.
COMPETING SERIES: These are the Caldwell(WA), Harana(OR), Jett(OR), Keigley(UT), Loupence(T ID), Rustico(T UT), and Snow(WA) series. Caldwell soils are noncalcareous throughout, and are somewhat poorly drained and contain mottles below 40 inches. Harana soils have a particle size control section that contains 27 to 35 percent clay. Jett soils are calcareous throughout. Keigley soils are strongly calcareous throughout with 15 to 30 percent calcium carbonate equivalent and lack Bw horizons. Loupence soils are noncalcareous throughout, receive 8 to 10 inches annual precipitation,and are dry more than half the time in the moisture control section. Rustico soils have annual precipitation of 8 to 12 inches and the control section averages 27 to 35 percent clay. Snow soils are calcareous throughout and have slightly hard consistence.
GEOGRAPHIC SETTING: Red Rock soils occur on alluvial fans, stream terraces and lake terraces at elevations of 4,300 to 5,800 feet. Slopes are most commonly 0 to 3 percent and range from 0 to 6 percent. These soils formed in mixed alluvium or reworked lacustrine deposits. The climate is dry subhumid with 12 to 16 inches of annual precipitation and 90 to 140 frost free days. The mean annual air temperature ranges from 45 to 55 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bandag, Calita, Erda, Hansel, Hupp, Kearns, Parleys, Postma, Taylorsflat, and Timpanogos soils. Bandag, Hansel, and Postma soils have ochric epipedons, and Hansel soils have argillic horizons. Hupp soils are calcareous throughout and have more than 35 percent coarse fragments. Kearns soils have mollic epipedons less than 20 inches thick. Taylorsflat soils have an ochric epipedon and calcic horizon. Calita and Erda soils have calcic horizons. Timpanogos and Parleys soils have argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; slow or medium runoff; moderate permeability.
USE AND VEGETATION: Dry cropland. Native vegetation is big sagebrush, Great Basin wildrye, bluebunch wheatgrass, and cheat grass.
DISTRIBUTION AND EXTENT: Western Utah. Moderately extensive. MLRA 28A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Salt Lake Area, Utah, 1936.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the surface of the soil to 37 inches. (Ap, A2, Bw1, and Bw2 horizons)