LOCATION SPUKWUSH WAEstablished Series
TAXONOMIC CLASS: Ashy over loamy, amorphic over isotic Typic Vitricryands
TYPICAL PEDON: Spukwush loamy sand - in a clearcut area. (Colors are for moist soil unless otherwise noted. All textures are apparent field textures.)
A--0 to 2 inches; brown (7.5YR 4/4) loamy sand (volcanic ash and pumice) pinkish gray (7.5YR 6/2) dry; single grain; loose, nonsticky and nonplastic; few medium and coarse and common very fine and fine roots; 10 percent 2 to 6 mm diameter cinders; strongly acid (pH 5.2); abrupt smooth boundary. (1 to 2 inches thick)
Bs1--2 to 4 inches; strong brown (7.5YR 5/6) loamy sand, (volcanic ash and pumice) light yellowish brown (10YR 6/4) dry; single grain; loose, nonsticky and nonplastic; few medium and coarse and common very fine and fine roots; 15 percent 2 to 6 mm diameter cinders; strongly acid (pH 5.4); abrupt smooth boundary. (2 to 5 inches thick)
Bs2--4 to 7 inches; strong brown (7.5YR 5/6) and pale brown (10YR 6/3) loamy sand (volcanic ash and pumice) strong brown (7.5YR 5/6) and white (10YR 8/1) variegated, dry; single grain; loose, nonsticky and nonplastic, weakly smeary; few medium and common very fine and fine roots; 5 percent 2 to 6 mm diameter cinders; 5 percent pebbles; strongly acid (pH 5.4); clear smooth boundary. (3 to 8 inches thick)
Bs3--7 to 15 inches; brown (10YR 5/3) very cindery sandy loam (volcanic ash and pumice) very pale brown (10YR 7/4) dry; weak fine subangular blocky structure; soft, very friable, slightly sticky, slightly plastic, weakly smeary; few medium and coarse and common fine roots; 20 percent pebbles and 30 percent 2 to 6 mm diameter cinders; strongly acid (pH 5.4); abrupt smooth boundary. (4 to 9 inches thick)
2Bsb1--15 to 30 inches; yellowish brown (10YR 5/4) loam, very pale brown (10YR 8/3) dry; moderate medium subangular blocky structure; slightly hard, friable, sticky, plastic; few fine and medium roots; few very fine and fine irregular pores; 3 percent pebbles; moderately acid (pH 5.6); clear smooth boundary. (12 to 18 inches thick)
2Bsb2--30 to 36 inches; light yellowish brown (10YR 6/4) loam, very pale brown (10YR 8/3) dry; moderate medium subangular blocky structure; slightly hard, friable, sticky, plastic; bands of yellowish brown (5YR 5/8) and light gray (10YR 7/2), reddish yellow (7.5YR 6/8) dry; few very fine and fine irregular pores; 10 percent pebbles, moderately acid (pH 5.8); clear smooth boundary. (4 to 7 inches thick)
2Cb1--36 to 39 inches; light yellowish brown (10YR 6/4), with flakes of white (10YR 8/1) loam, bands of white (10YR 8/1) and very pale brown (10YR 7/3) dry; moderate medium subangular blocky structure; slightly hard, friable, sticky, plastic; few very fine and fine random tubular and irregular pores; 10 percent pebbles; moderately acid (pH 5.9); clear smooth boundary. (3 to 5 inches, 7.5 to 12.5 cm thick.)
2Cb2--39 to 60 inches; light yellowish brown (10YR 6/4) gravelly loam, very pale brown (10YR 8/3) dry; moderate medium subangular blocky structure; slightly hard, friable, sticky, plastic; few very fine and fine random tubular and irregular pores; 20 percent pebbles; slightly acid (pH 6.1).
TYPE LOCATION: Snoqualmie Pass Area, King County, Washington; 1,000 feet north and 1,200 feet east of the southwest corner, sec. 17, T. 19 N., R. 10 E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 41 to 45 degrees F. The solum thickness ranges from 24 to 40 inches. The lower part of the control section averages from 15 to 30 percent rock fragments and 18 to 27 percent clay. The ashy layers are 14 to 24 inches thick.
The A horizon has hue of 7.5YR or 10YR, value of 4 to 6 moist, 6 or 7 dry, and chroma of 1 to 4 moist, 1 or 2 dry.
The Bs horizon has matrix colors that have hue of 7.5YR or 10YR, value of 4 to 6 moist, 5 or 6 dry, and chroma of 3 to 6 moist or dry. Some pedons have streaks and variegations with value up to 8 dry and chroma from 1 to 6 moist and dry. It is loamy sand or sandy loam modified by 5 to 30 percent pumice and cinders. Some pedons contain 5 to 15 percent hard pebbles.
The 2Bsb horizon is loam or clay loam and contains 2 to 15 percent pebbles.
The 2C horizon has hue of 7.5YR or 10YR, value of 4 to 6 moist, 7 or 8 dry, and chroma of 1 to 4 moist or dry. It contains from 5 to 25 percent pebbles. It is slightly acid or moderately acid.
COMPETING SERIES: These are the Scar and Tusip series. Scar and Tusip soils have 10 to 18 percent clay in the lower part of the particle-size control section. In addition, Scar soils have a xeric moisture regime.
GEOGRAPHIC SETTING: Spukwush soils are on mountainous slump areas at elevations of 2,700 to 4,000 feet. Slopes range from 8 to 30 percent. These soils formed in volcanic ash and cinders overlying weathered tuffaceous material. The mean annual precipitation ranges from 70 to 100 inches with most in the form of snow and rain during the winter months. Mean January temperature is about 27 degrees F, the mean July temperature is about 60 degrees F, and the mean annual temperature is about 43 degrees F. The frost-free season is 110 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dobbs, Foss, Haywire, Littlejohn, Nagrom, Nimue, Pitcher, and Playco soils. Haywire, Littlejohn, Nagrom, Nimue, and Playco soils are loamy-skeletal. Dobbs soils are frigid. Foss soils are medial over loamy-skeletal. Littlejohn and Pitcher soils are frigid. Haywire and Nagrom soils have a lithic contact between 20 and 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderately slow permeability.
USE AND VEGETATION: Mostly used for timber production. Native vegetation is western hemlock, Douglas-fir, and Pacific silver fir with an understory of red huckleberry, deer fern, evergreen huckleberry, Oregon-grape, longtube twinflower, western swordfern, western brackenfern, devilsclub, and currant.
DISTRIBUTION AND EXTENT: West slopes of the Cascade Mountains in central Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Snoqualmie Pass Area, Pierce County, Washington, 1986.
REMARKS: Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the mineral surface to 2 inches; a spodic horizon from 2 to 36 inches. The soil is more than 60 percent volcanic ash and cinders from the mineral surface to 15 inches. The spodic horizon is assumed not to meet chemical criteria for a spodic horizon but is assumed to have silt-sized and larger pellets and cracked coatings on sand grains.