LOCATION ALTAPEAK WAEstablished Series
TAXONOMIC CLASS: Ashy-skeletal over sandy or sandy-skeletal, amorphic over isotic Andic Haplocryods
TYPICAL PEDON: Altapeak ashy loamy sand - forested (color is for moist soil unless otherwise stated. All textures are apparent field textures).
Oi--0 to 1 inch; slightly decomposed loose forest litter, needles, twigs, bark and moss. (1 to 3 inches thick)
Oa--1 to 3 inches; black (10YR 2/1) highly decomposed organic matter that is matted and bound by roots; abrupt wavy boundary. (0 to 5 inches thick)
E--3 to 5 inches; pinkish gray (7.5YR 6/2) ashy loamy sand (volcanic ash), light gray (7.5YR 7/1) dry; weak moderate subangular blocky structure; soft, very friable, nonsticky, nonplastic; many very fine roots; many very fine and fine interstitial pores; NaF pH 9.2; very strongly acid (pH 5.0); abrupt wavy boundary. (1 to 3 inches thick)
Bhs--5 to 19 inches; dark reddish brown (2.5YR 2/4) and yellowish red (5YR 5/8) very gravelly ashy sandy loam (large amount of volcanic ash), strong brown (7.5YR 5/6) and reddish brown (5YR 4/4) dry; moderate medium subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; many very fine and fine and common medium and coarse roots; many very fine and fine interstitial pores; 15 percent cobbles and 20 percent gravel and hard cinders; NaF pH 12.0+; moderately acid (pH 5.8); clear irregular boundary. (3 to 14 inches thick)
Bs--19 to 27 inches; strong brown (7.5YR 5/6) very cobbly ashy loamy sand, reddish yellow (7.5YR 6/6) dry; weak moderate subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic, common very fine and fine and few medium and coarse roots; many very fine and fine interstitial pores; 20 percent cobbles, 20 percent gravel; NaF pH 12.0+; moderately acid (pH 5.6); clear smooth boundary. (6 to 8 inches thick)
2C1--27 to 36 inches; pale yellow (2.5Y 7/4) extremely cobbly loamy sand, very pale brown (10YR 7/3) dry; massive; hard, friable, slightly sticky and nonplastic; common fine roots; common very fine and fine interstitial pores; 15 percent gravel; 45 percent cobbles; NaF pH 11.5; moderately acid (pH 5.8); gradual smooth boundary. (6 to 24 inches thick)
2C2--36 to 53 inches; grayish brown (2.5Y 5/2) extremely gravelly coarse sand, light brownish gray (2.5Y 6/2) dry; massive; hard, friable; few fine roots; 45 percent gravel, 25 percent cobbles; NaF pH 11.5; slightly acid (pH 6.2); gradual irregular boundary. (0 to 20 inches thick)
2Cr--53 inches; grayish brown (2.5Y 5/2) highly weathered granodiorite; light brownish gray (2.5Y 6/2) dry; this material can be cut with a spade with difficulty and textures as very gravelly coarse sand; 65 percent hard gravel; slightly acid (pH 6.2).
TYPE LOCATION: Snoqualmie Pass Area, King County, Washington; in upper Hansen Creek drainage, about 200 feet west of spur off Forest Service Road number 2291A; 1,000 feet south and 900 feet east of the northwest corner of sec. 28, T. 22 N., R. 10 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 37 to 42 degrees F. Depth to a paralithic contact is 40 to 60 inches. The solum and upper part of the particle-size control section has an estimated moist bulk density of 0.75 to 1.40 g/cc, volcanic glass content of 30 to 60 percent, acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of more than 2.0 percent and 15-bar water retention of 5 to 12 percent for air-dried samples. Rock fragments, including hard cinders in the control section, average 35 to 70 percent. Bedrock is granitic rock, or low grade metamorphic rock including slate and phyllite. Depth to the lithologic discontinuity is 14 to 25 inches.
The E horizon has hue of 5YR, 7.5YR or 10YR, value of 4 through 7 moist and 6 or 7 dry, and chroma of 0 through 2 moist and dry. There is tonguing of this horizon into the B horizon in some pedons. It is strongly acid or very strongly acid.
The Bhs horizon has hue of 2.5YR or 5YR moist and 5YR or 7.5YR dry, values are 2 through 5 moist and 4 or 5 dry, chroma is 4 through 8 moist and 4 through 6 dry. There is up to 15 percent black organic staining up to 2mm in diameter in some pedons. Texture is ashy sandy loam or ashy loam modified by 15 to 45 percent coarse fragments including hard cinders. Structure is weakly to strongly expressed. There are two distinct Bhs horizons in some pedons. In pedons where there are two distinct Bhs horizons, the structure in the upper horizon is strong subangular or angular blocky.
The Bs horizon has value of 4 or 5 moist and 5 or 6 dry, and chroma of 4 through 6 moist and dry. It is very gravelly ashy loamy sand or very gravelly ashy sandy loam. It is slightly acid to strongly acid.
The 2C horizon has hue of 10YR or 2.5Y, value of 4 through 7 moist and dry, and chroma of 2 through 4 moist and 2 or 3 dry. The fine earth fraction is loamy sand, coarse sand or loamy coarse sand. Coarse fragments are angular and residual in origin and range from 45 to 75 percent by volume. The horizon is massive exhibiting some rock structure. Some pedons have weak, fine subangular blocky structure or single grain. It is slightly acid to strongly acid.
COMPETING SERIES: These are the Index, Serene and Skipeak series. Serene soils are 20 to 40 inches to paralithic contact. Skipeak soils do not have a Bhs horizon, and have mixed rounded rock fragments of mixed lithology in the particle-size control section. Index soils have a mean annual soil temperature of 42 to 46 degrees F.
GEOGRAPHIC SETTING: Altapeak soils are on mountain slopes at 3,200 to 5,600 feet in elevation. Slopes range from 3 to 90 percent. Altapeak soils formed in a thin mantle of volcanic ash and cinders over residuum and colluvium from granitic and low grade metamorphic rocks including slate and phyllite. The climate is maritime influenced with cold, wet winters, and cool, moist summers. The mean January temperature is about 27 degrees F, the mean July temperature is about 58 degrees F, mean annual air temperature is about 40 degrees F. Annual precipitation is 70 to 130 inches, with a considerable portion of this being in the form of snow. Frost-free season is 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Index and Serene soils and the Haywire, Klapatche, Nagrom, Nimue, Playco, Reggad, Serene, Shuksan, and Spukwash soils. Nagrom, Haywire, Nimue, Playco, and Shuksan soils are loamy-skeletal. Shuksan soils have a paralithic contact with dense glacial till at 20 to 40 inches. Haywire, Klapatche, and Nagrom soils are 20 to 40 inches deep to a lithic contact. Reggad soils are fragmental and lack a spodic horizon. Spukwash soils are ashy over-loamy horizon.
DRAINAGE AND PERMEABILITY: Well drained, slow to rapid runoff; moderately rapid permeability in the upper part and rapid below.
USE AND VEGETATION: Used for timber production, watershed, and wildlife habitat. Native vegetation is western hemlock, Pacific silver fir, noble fir, Alaska yellow cedar, and mountain hemlock, with an undergrowth of common beargrass, longtube twinflower, bunchberry dogwood, huckleberry, princes pine, deer fern, lupine, salal, and cascade azalea.
DISTRIBUTION AND EXTENT: West and east slopes of the Cascade Mountains in west central Washington; MLRA 3. Series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Snoqualmie Pass Area, King County, Washington, 1987.
REMARKS: Partial laboratory data are available on this soil. NSSL numbers 80T7089-7090. Diagnostic horizons and features recognized in this pedon are an albic horizon from the mineral surface to 2 inches, a spodic horizon from 5 to 27 inches, and a paralithic contact at 53 inches. The particle-size class was updated to ashy-skeletal over sandy or sandy-skeletal on 8/2007 due to addition of this class in the 10th edition of Keys to Soil Taxonomy.