LOCATION MOWICH WAEstablished Series
TAXONOMIC CLASS: Coarse-silty over clayey, isotic over smectitic, frigid Aquic Haplorthods
TYPICAL PEDON: Mowich silt loam - on a 3 percent southwest facing slope under coniferous forest at 2,020 feet elevation. (Colors are for moist soil unless otherwise stated. All textures are apparent field textures. When described the soil was moist to 24 inches, saturated below.)
Oi--8 to 5 inches; accumulation of needles, twigs, leaves, and mosses.
Oa--5 inches to 0; decomposed forest litter; many very fine, fine, and medium roots; abrupt smooth boundary.
A--0 to 7 inches; dark brown (7.5YR 3/2) silt loam, brown (7.5YR 5/2) dry; moderate medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic, moderately smeary; many very fine fine, medium, and coarse roots; common very fine
tubular pores; very strongly acid (pH 4.6); abrupt wavy boundary. (5 to 10 inches thick)
Bs1--7 to 10 inches; strong brown (7.5YR 5/6) silt loam, reddish yellow (7.5YR 6/6) dry; reddish brown (5YR 4/4) iron oxide coatings on 20 percent of the ped faces; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic, moderately smeary; common very fine and fine roots; common very fine tubular pores; very strongly acid (pH 4.8); clear wavy boundary. (0 to 5 inches thick)
Bs2--10 to 26 inches; dark yellowish brown (10 YR 4/4) silt loam, light yellowish brown (10YR 6/4) dry; common fine distinct yellowish red (5YR 4/6) mottles, and few fine distinct light brown gray (10YR 4/2) mottles; moderate medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; moderately smeary; few very fine and fine roots; many very fine tubular pores; very strongly acid (pH 4.8); clear smooth boundary. (14 to 25 inches thick)
2Cg--26 to 60 inches; light brownish gray (2.5Y 6/2) silty clay, light gray (2.5Y 7/2) dry; many fine and medium prominent yellowish red (5YR 5/8) mottles; massive; very hard, firm, sticky, plastic; few very fine tubular pores; very strongly acid (pH 5.0).
TYPE LOCATION: Snoqualmie Pass Area, Pierce County, Washington; 150 feet south of St. Regis Paper Company 0-6011 Road; 1,600 feet east, 800 feet south of the northwest corner sec. 35, T. 17 N., R. 5 E. W.M.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 43 to 46 degrees F. Depth to the 2Cg horizon ranges from 20 to 35 inches. Coarse fragments in the control section range from 0 to 15 percent by volume. Reaction is very strongly acid or strongly acid throughout. Depth to mottles with chroma of 2 or less is 10 to 25 inches.
The A horizon has hue of 7.5YR or 10YR moist or dry; value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist or dry. Structure is subangular blocky or granular.
The Bs1 horizon, where present, has hue of 5YR or 7.5YR moist or dry, value of 4 or 5 moist, 5 or 6 dry, and chroma of 4 through 6 moist or dry.
The Bs2 horizon has value of 4 through 6 moist, 5 through 7 dry, and chroma of 2 through 4 moist or dry. Texture is silt loam or loam.
The 2Cg horizon has hue of 10YR, 2.5Y, or 5Y, value of 4 through 6 moist, 6 through 8 dry, and chroma of 1 or 2 moist or dry. Texture is silty clay or clay.
COMPETING SERIES: These are the Skipopa and Whatcom series in other families. These soils have an argillic horizon and are mesic. In addition, Whatcom soils are fine-loamy.
GEOGRAPHIC SETTING: Mowich soils are on preglacial lake plains. These soils formed in volcanic ash overlying glaciolacustrine sediments associated with Pleistocene valley glaciation. Slopes are 0 to 15 percent. The climate is marine influenced, with relatively cool, dry summers and cool, wet winters. Average annual precipitation is 55 to 75 inches, which includes an average 4 feet snowfall. Mean January temperature is about 31 degrees F, mean July temperature is about 60 degrees F, and the mean annual temperature is 45 degrees F. The growing season (28 degrees F) is 150 to 170 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Alkiridge, Mashel, Rugles, Scamman, and Zynbar soils. Alkiridge soils are ashy over loamy- skeletal and are cryic. Rugles and Zynbar soils are well drained and are medial. Mashel and Scamman soils are mesic and have an argillic horizon.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow to medium runoff; moderate permeability in the solum, slow permeability in the substratum. A perched water table occurs as high as 1 to 2 feet at times from November through May.
USE AND VEGETATION: Timber production, watershed, and wildlife habitat are the principal uses. Native vegetation is Douglas-fir, western hemlock, western redcedar, and red alder. Understory species include western swordfern, vine maple, salal, deer fern, and red huckleberry.
DISTRIBUTION AND EXTENT: West slopes of the central Cascade Mountains in western Washington. 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 7 inches, a sodic horizon from 7 to 26 inches, and a lithologic change from weathered volcanic ash to glacial lake sediments at 26 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.