LOCATION SWAKANE WAEstablished Series
The Swakane series consists of shallow, well drained soils formed in residuum and colluvium from granitic and meta-igneous rocks with an influence of loess and volcanic ash in the upper part. Swakane soils are on uplands, hills and mountains and have slopes of 0 to 90 percent. The mean annual precipitation is about 15 inches and mean annual temperature is about 48 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Lithic Ultic Haploxerolls
TYPICAL PEDON: Swakane cobbly ashy loam on a 45 percent south-facing slope at 2,720 feet elevation under native range vegetation. (Colors are for dry soil unless otherwise noted.)
A1--0 to 6 inches; grayish brown (10YR 5/2) cobbly ashy loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots; common fine tubular pores; 15 percent gravel, 10 percent cobbles; neutral (pH 6.6); clear wavy boundary. (3 to 8 inches thick)
A2--6 to 11 inches; grayish brown (10YR 5/2) very gravelly ashy loam, very dark grayish brown (10YR 3/2) moist; massive; soft, very friable, nonsticky and nonplastic; common fine roots; common fine tubular and interstitial pores; 40 percent gravel, 15 percent cobbles; neutral (pH 6.8); clear wavy boundary. (0 to 8 inches thick)
2C--11 to 14 inches; brown (10YR 5/3) extremely gravelly sandy loam, dark brown (10YR 3/3) moist; massive; soft, very friable, slightly sticky and slightly plastic; few fine roots; common fine tubular and irregular pores; 45 percent gravel, 15 percent cobbles; neutral (pH 7.0); gradual wavy boundary. (0 to 12 inches thick)
2R--14 inches; unweathered granite.
TYPE LOCATION: Colville Indian Reservation; Okanogan County, Washington; about 6 miles east of the Colville Indian Agency; 1,000 feet west, 100 feet north of the southeast corner of section 1, T. 30 N., R. 31 E., W.M.
RANGE IN CHARACTERISTICS:
Depth to diagnostic horizons and features are measured from the top of the first mineral layer.
Average annual soil temperature - 47 to 52 degrees F.
Moisture control section - dry in all parts to the lithic contact 90 to 105 days after the summer solstice, July to September, moist October through June
Depth to hard bedrock contact - 10 to 20 inches
Thin recent (1980) volcanic ash layer - .25 to .75 inch thick present in some pedons between the organic and mineral soil surface
Base saturation - 50 to 75 percent (by sum of cations)
Volcanic ash influence - 7 to 12 inches thick
Estimated properties of the volcanic ash influenced layers:
Volcanic glass content - 5 to 20 percent
Acid oxalate Al + 1/2 Fe - 0.4 to 1.0 percent
Moist bulk density - 1.0 to 1.2 g/cc
15 bar water retention - 5 to 10 percent on air-dried samples
Particle-size control section:
Clay content - 5 to 15 percent
Sand content - 25 to 55 percent medium and coarse
Rock fragment content - 35 to 70 percent
A horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 to 4 dry and 1 to 3 moist
Texture - Ashy loam, ashy fine sandy loam, ashy sandy loam
Clay content - 5 to 15 percent
Gravel content - 10 to 40 percent
Cobble content - 0 to 15 percent
Stones and boulder content - 0 to 10 percent
Reaction - moderately acid to neutral.
Some pedons have an AB or a Bw horizon.
C horizon (absent in some pedons)
Hue - 10YR, 2.5Y, or is multicolored
Value - 4 to 7 dry, 3 to 5 moist
Chroma - 2 to 4 dry or moist
Texture - loam, sandy loam, loamy sand, coarse sandy loam
Clay content - 5 to 15 percent
Gravel content - 20 to 60 percent
Cobble content - 0 to 25 percent
Stone content - 0 to 10 percent
Reaction - slightly acid to slightly alkaline.
COMPETING SERIES: These are the Brisky, Borid, Buckrock, Cox, Rufus, and Witzel series. Brisky soils are dry for 75 to 90 days and have 35 to 50 percent sandstone rock fragments in the particle-size control section. Borid and Cox soils have an aridic moisture regime. Buckrock soils have less than 25 percent medium and coarse sand and 35 to 65 percent rock fragments in the control section of sedimentary and volcanic origin. A similar soil with isotic mineralogy is the Rufus series. Rufus soils are dry for 75 to 90 days and have 35 to 80 percent shaly rock fragments in the control section. A Similar soil with an active CEC class is the Witzel series. Witzel soils have hue of 7.5YR or 5YR and more than 18 percent clay in the particle-size control section.
GEOGRAPHIC SETTING: Swakane soils are on ridges, shoulders, and backslopes of hills and mountains. These soils formed in residuum and colluvium from granite, granodiorite, quartz monzonite, and granitic gneiss with an influence of loess and volcanic ash. Slopes are 0 to 90 percent. Elevation is 1,100 to 4,900 feet. The climate is characterized by warm, dry summers and cool, moist winters. The mean annual precipitation is 12 to 22 inches. The mean January temperature is about 26 degrees F. and the mean mean July temperature is about 70 degrees F. The mean annual air temperature is about 48 degrees F. The frost-free season is 100 to 165 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Conconully, Dinkelman, Donavan, Ginnis, Skanid, Spokane, Tyee, Vanbrunt and Wynhoff soils. Conconully, Dinkelman, Donavan, Ginnis, Spokane, Vanbrunt, and Wynhoff soils are greater than 20 inches deep to a lithic contact. Conconully soils are on undulating ground moraines and foothills. Dinkelman soils are on footslopes and side slopes. Ginnis soils are on footslopes, backslopes, and shoulders of hills. Spokane soils are on foothills, mountains, and ridgetops. Vanbrunt soils are on mountain ridges, shoulders, and backslopes. Wynhoff soils are on shoulders, backslopes, and footslopes of hills and mountains. Skanid and Tyee soils are 10 to 20 inches deep to a paralithic contact with weathered granitic bedrock. Skanid soils are on mountains. Tyee soils are on mountain side slopes.
DRAINAGE AND PERMEABILITY: Well drained, slow to rapid runoff, moderate permeability.
USE AND VEGETATION: These soils are used for livestock grazing, wildlife habitat, homesite development and watersheds. Potential natural vegetation is bluebunch wheatgrass, Sandberg bluegrass, arrowleaf balsamroot, Wyeth eriogonum, snow eriogonum, common yarrow, antelope bitterbrush, and widely spaced stunted ponderosa pine.
DISTRIBUTION AND EXTENT: North-central and north-eastern Washington. MLRA 6. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Colville Indian Reservation, Okanogan County, Washington, 1987.
REMARKS: Diagnostic horizons and features recognized in this soil are:
Mollic epipedon - the zone from 0 to 11 inches (A1 and A2 horizon)
Vitrandic feature - the zone from 0 to 11 inches (A1 and A2 horizons)
Lithic contact -the zone beginning at 14 inches
Particle-size control section - the zone from 0 to 14 inches
Base saturation (sum of cations) is estimated to be 50 to 75 percent.