LOCATION ROCK CREEK WA+IDEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Lithic Mollic Haploxeralfs
TYPICAL PEDON: Rock Creek stony loam - grassland. (colors are for dry soil unless otherwise noted.)
A--0 to 2 inches; reddish brown (5YR 5/3) stony loam, dark reddish brown (5YR 3/3) moist; weak medium granular structure; slightly hard, friable, slightly sticky, and slightly plastic; many fine roots; many fine vesicular pores; 10 percent stones, 5 percent cobbles and 15 percent gravel; neutral (pH 6.6); abrupt smooth boundary. (1 to 3 inches thick)
Bt1--2 to 7 inches; reddish brown (5YR 5/4) cobbly clay loam, dark reddish brown (5YR 3/4) moist; weak thick platy structure; hard, firm, moderately sticky and moderately plastic; common fine roots; many fine vesicular pores; 15 percent cobbles and 15 percent gravel; few faint clay films; neutral (pH 6.6); gradual wavy boundary. (2 to 6 inches thick)
Bt2--7 to 10 inches; reddish brown (5YR 5/4) extremely cobbly clay loam, dark reddish brown (5YR 3/4) moist; massive; hard, firm, moderately sticky and moderately plastic; few roots forming mats on basalt fragments; 30 percent cobbles, 35 percent gravel and 5 percent stones; few distinct clay films on basalt fragments and on fracture planes; neutral (pH 6.6); abrupt wavy boundary. (2 to 6 inches thick)
Bt3--10 to 14 inches; brown (7.5YR 4/4) extremely cobbly clay, dark brown (7.5YR 3/4) moist; massive; extremely hard, firm, very sticky and moderately plastic; few roots forming mats on basalt fragments; 40 percent cobbles, 45 percent gravel and 5 percent stones; common distinct clay films on basalt fragments and along fracture planes; neutral (pH 6.6); gradual wavy boundary. (0 to 6 inches thick)
R--14 inches; fractured basalt
TYPE LOCATION: Yakima County, Washington; 3/4 mile east of Fort Simcoe, 600 feet north of State Highway 3B, SW 1/4 SE 1/4 sec. 16, T. 10 N., R. 16 E., WM.
RANGE IN CHARACTERISTICS: The mean annual soil temperature at the lithic contact is 47 to 52 degrees F. Depth to the lithic contact ranges from 8 to 20 inches. The particle-size control section contains 35 to 45 percent clay in the fine-earth fraction and 35 to 90 percent rock fragments. Soil reaction is neutral or slightly acid.
The A horizon has hue of 5YR, 7.5YR, or 10YR, value of 4 or 5 dry, 2 to 4 moist and chroma of 2 or 3 dry or moist. Texture of the fine-earth fraction is loam or silt loam and is very stony, very cobbly, gravelly, cobbly, or stony. It has weak or moderate structure.
The Bt horizon has hue of 5YR or 7.5YR and value of 4 or 5 dry, 3 or 4 moist and chroma of 2 to 4 dry, 2 or 3 moist. Texture of the fine-earth section is silty clay loam, clay loam, silty clay, or clay and is extremely cobbly, extremely gravelly, very cobbly or very gravelly. It has clay films on faces of peds and on rock fragments.
COMPETING SERIES: There are no competing series. Similar soils are the Bakeoven, Lickskillet and Vantage series. These soils have a mollic epipedon and the Bakeoven and Lickskillet soils are loamy-skeletal and lack an argillic horizon.
GEOGRAPHIC SETTING: These soils are on plateaus, canyon side slopes, and ridgetops at elevations of 1,200 to 4,200 feet. Slopes are 0 to 70 percent. They formed in residuum derived from basalt mixed with loess. They are in a climate has warm, dry summers and cool, moist winters. The mean annual precipitation is 10 to 16 inches. The mean annual temperature is 46 to 50 degrees F. The frost-free season is 120 to 170 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Clint, Harwood, McDaniel, Simcoe, and Taneum soils. All of these soils have a mollic epipedon. Clint soils lack an argillic horizon and are on side slopes. Harwood soils are 20 to 40 inches deep to a duripan and are on uplands and dissected terraces. McDaniel soils are more than 60 inches deep and are on canyon side slopes and hillslopes. Simcoe soils are 30 to 40 inches deep over a lithic contact and are on hillslopes. Taneum soils are more than 40 inches deep and have less than 15 percent coarse fragments and are on mountain slopes and hillslopes.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used for rangeland and wildlife habitat. Native vegetation is bluegrass, bluebunch wheatgrass, bighead clover, hooker balsamroot, biscuitroots, stiff (scab) sagebrush, Eriogonum, phlox, wild onion, violet, and windflower.
DISTRIBUTION AND EXTENT: Southern and eastern Washington; MLRA 8. Series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Yakima County, Washington, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Ochric epipedon
Argillic horizon - from 2 to 14 inches (Bt1, Bt2, and Bt3 horizons)
Lithic contact - at 14 inches
Particle-size control section - from 2 to 14 inches
Mollic feature - value of 3 moist to 15 inches with 0.7 percent or more organic carbon within the upper 4 inches.