LOCATION ROCK CREEK WA+IDEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Lithic Mollic Haploxeralfs
TYPICAL PEDON: Rock Creek stony loam, rangeland, on a 3 percent, east-facing, linear slope at an elevation of 1,300 feet. (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; friable, slightly hard, slightly sticky and slightly plastic; many fine roots; many fine vesicular pores; 5 percent cobbles, 10 percent stones 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; firm, hard, moderately sticky and moderately plastic; common fine roots; many fine vesicular pores; few faint clay films; 15 percent gravel and 15 percent cobbles; neutral (pH 6.6); gradual wavy boundary. (3 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; firm, hard, moderately sticky and moderately plastic; few roots around fragments; few distinct clay films on rock fragments on all faces of peds; 5 percent stones, 30 percent cobbles and 35 percent gravel; 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; firm, hard, very sticky and moderately plastic; few roots around fragments; common distinct clay films on rock fragments and on all faces of peds; 5 percent stones, 40 percent cobbles, and 45 percent gravel; neutral (pH 6.6); gradual wavy boundary. (0 to 6 inches thick)
R--14 inches; fractured basalt bedrock.
TYPE LOCATION: Yakima Nation, Yakima County, Washington; approximately 3/4 of a mile east of Fort Simcoe, and 600 feet north of State Highway 3B, located about 2,200 feet west and 300 feet north of the southeast corner of sec. 16, T. 10 N., R. 16 E., Fort Simcoe USGS quad; lat. 46 degrees, 20 minutes, 49 seconds N. and long.120 degrees, 49 minutes, 33 seconds W., NAD83.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 52 degrees F. The particle-size control section averages 35 to 45 percent clay and 35 to 90 percent rock fragments. All horizons are neutral or slightly acid. Depth to bedrock is 8 to 20 inches.
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. It is very stony, very cobbly, gravelly, cobbly, or stony.
The Bt horizon has hue of 5YR, 7.5YR or 10YR, value of 4 to 6 dry, 3 or 4 moist, and chroma of 2 or 3 dry or moist. It is silty clay loam, clay loam, silty clay, or clay and is extremely cobbly, extremely gravelly, very cobbly or very gravelly.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Rock Creek soils are on plateaus, side slopes, and ridgetops. They formed in residuum from basalt. Slope ranges from 0 to 70 percent. Elevations are 1,200 to 4,200 feet. The climate is characterized by warm, dry summers and cool, moist winters. The mean annual precipitation is 12 to 16 inches. The mean annual temperature is 48 degrees F. The frost-free period is 100 to 170 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bridgewater, Cooscanyon, Hatspring, Onepenne and Selah soils. Bridgewater soils are loamy-skeletal and very deep Mollisols on floodplains. Cooscanyon soils are loamy-skeletal and very deep Mollisols on valley floors and stream terraces. Hatspring soils are fine-loamy and moderately deep Mollisols on plateaus. Onepenne soils are loamy and shallow on plateaus. Selah soils have a duripan at 20 to 40 inches, a mollic epipedon that is 7 to 16 inches thick, are fine-loamy and on uplands and dissected terraces.
DRAINAGE AND PERMEABILITY: Well drained, slow to medium runoff, moderately low saturated hydraulic conductivity.
USE AND VEGETATION: These soils are used for grazing and wildlife. Native vegetation is Sandberg bluegrass, bluebunch wheatgrass, largehead clover, Hooker's balsamroot, biscuitroot, stiff sagebrush, Douglas buckwheat, Hood's phlox, wild onion, sagebrush violet, and narrowleaf goldenweed.
DISTRIBUTION AND EXTENT: Southern and eastern Washington; MLRA 7 and 8. Series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Yakima Nation, Yakima County, Washington, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Ochric epipedon - 0 to 2 inches (A horizon).
Argillic horizon - 2 to 14 inches (Bt1, Bt2, and Bt3 horizons).
Lithic contact - 14 inches (top of R horizon).
Particle-size control section - 2 to 14 inches (Bt1, Bt2, and Bt3 horizons).
Mollic feature - color value of 3 moist with 0.7 percent or more organic carbon within the upper 4 inches.