LOCATION REBECCA WAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Ultic Haploxerolls
TYPICAL PEDON: Rebecca gravelly sandy loam - on a 4 percent northeast-facing slope at 2,260 feet elevation, under native grasses and shrubs. (Colors are for dry soil unless otherwise noted. All textures are apparent field textures)
A1--0 to 9 inches; dark grayish brown (10YR 4/2) gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; weak very fine subangular blocky parting to weak fine granular structure; slightly hard, very friable, slightly sticky, slightly plastic; many very fine and fine roots; 20 percent subrounded pebbles; neutral (pH 6.6); clear smooth boundary. (5 to 13 inches thick)
A2--9 to 15 inches; grayish brown (10YR 5/2) gravelly sandy loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky, nonplastic; common very fine and fine roots; 30 percent subrounded pebbles; neutral (pH 7.0) clear smooth boundary. (6 to 12 inches thick)
Bw1--15 to 29 inches; pale brown (10YR 6/3) gravelly sandy loam, brown (10YR 5/3) moist; weak fine subangular structure; soft, very friable, slightly sticky, nonplastic; common very fine and fine roots; 20 percent subrounded pebbles; neutral (pH 7.0); clear smooth boundary.
Bw2--29 to 45 inches; light yellowish brown (10YR 6/4) gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky, nonplastic; common very fine and fine roots; 20 percent subrounded pebbles, neutral (pH 7.2); clear wavy boundary. (Combined thickness of the Bw horizon is 10 to 26 inches)
C--45 to 60 inches; light yellowish brown (10YR 6/4) gravelly coarse sandy loam, yellowish brown (10YR 5/4) moist; massive; soft, very friable, nonsticky, nonplastic; few very fine and fine roots; 30 percent pebbles; neutral (pH 7.2)
TYPE LOCATION: Colville Indian Reservation; Okanogan County, Washington; about 4 miles northeast of the town of Coulee Dam; 1,800 feet east, 1,200 feet south of the northwest corner of sec. 27, T. 29 N., R. 31 E., W.M.
RANGE IN CHARACTERISTICS: The mean annual soil temperature at a depth of 20 inches ranges from 49 to 51 degrees F. These soils are usually moist but are dry in all parts between depths of 8 and 24 inches for 90 to 105 consecutive days following the summer solstice. The mollic epipedon is 12 to 18 inches thick. The solum is 30 to 50 inches thick. The particle-size control section is 15 to 35 percent subrounded or subangular rock fragments and 5 to 15 percent clay.
The A horizon has value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3 dry or moist. It is 0 to 30 percent pebbles.
The Bw horizon has value of 5 or 6 dry, 4 or 5 moist, sand chroma of 3 or 4 dry or most. It is gravelly sandy loam or gravelly fine sandy loam and is 15 to 35 percent pebbles. Reaction is neutral or mildly alkaline.
The C horizon has value of 5 through 7 dry, 4 or 5 moist, and chroma of 2 through 4 dry or moist. It is gravelly sandy loam or gravelly coarse sandy loam and is 15 to 35 percent pebbles. Reaction is neutral or mildly alkaline.
COMPETING SERIES: These are the Ardening, Billyridge, Canderly, Catelli, Conconully, Crouch, Donavan, Fanal (T), Ginnis, Hellgate, Picard, Shangland, Spokane, Usk, and Windriver series. Ardening soils have 15 to 35 soft schist fragments in the particle-size control section and are dry for 60 to 75 consecutive days. Billyridge soils are dry for 60 to 75 consecutive days. Canderly soil have a mean annual soil temperature of 54 to 56 degrees F. Catelli, Ginnis, Shangland, Spokane, and Usk soils are 20 to 40 inches deep to a paralithic contact. Conconully soils have a C horizon in the lower part of the particle-size control section that is dense and hard when dry. Crouch soils have a mean annual soil temperature of about 55 degrees F. Donavan, Hellgate, and Phoebe soils are dry for 75 to 90 consecutive days. Fanal soils have mottles in the lower part of the B and in the C horizons. Owhi soils are sandy-skeletal in the lower part of the particle-size control section. Picard soils have 0 to 10 percent pebbles in the particle-size control section. Windriver soils have a mean annual soil temperature of 50 to 54 degrees F, and a solum 15 to 25 inches thick.
GEOGRAPHIC SETTING: Rebecca soils are on alluvial fans. These soils formed in alluvium of mixed mineralogy. Slopes are 0 to 15 percent. Elevation ranges from 1,200 to 2,600 feet. The climate is characterized by warm, dry summers and cool, moist winters. The average annual precipitation is 12 to 15 inches. The mean January temperature is about 25 degrees F, the mean July temperature is about 71 degrees F, and the mean annual air temperature is about 48 degrees F. The frost-free period is 110 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Beckley, Haley, Hobohill, Nespelem, Tyee, and Yaxon soils, and the competing Conconully and Ginnis soils. Haley soils are coarse-loamy over sandy or sandy-skeletal. Hobohill soils are sandy in the lower part of the particle-size control section. Nespelem soils are coarse-silty and have a weakly cemented duripan at a depth of 20 to 40 inches. Tyee soils are 20 to 20 inches deep to a paralithic contact with weathered granitic rock. Yaxon soils are fine-loamy and have an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderately rapid permeability.
USE AND VEGETATION: Livestock grazing, wildlife habitat, hay and pasture are the principal uses. Native vegetation is bluebunch wheatgrass, needleandthread, Thurber needlegrass, antelope bitterbrush, threetip sagebrush, Wyeth eriogonum, silky lupine, hood phlox, and micro pussytoes.
DISTRIBUTION AND EXTENT: Northeastern Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Colville Indian Reservation, Okanogan County, Washington, 1987.
REMARKS: Diagnostic horizons and features recognized in these soils ae a mollic epipedon from the surface to 15 inches, a cambic horizon from 15 to 45 inches, and a coarse-loamy, 10-to 40-inch, particle-size control section.