LOCATION SILVERHORN WAEstablished Series
TAXONOMIC CLASS: Fine, isotic Vertic Glossocryalfs
TYPICAL PEDON: Silverhorn gravelly loam - forestland, on a 42 percent slope with a northerly aspect at an elevation of 3,225 feet in a Pacific silver fir/Pacific rhododendron plant association. (When described on November 7, 1993, the soil was moist throughout. Colors are for moist soil unless otherwise stated.)
Oi--0 to 2 inches; slightly decomposed needles, leaves, and twigs; abrupt smooth boundary. (0.5 to 2 inches thick)
E1--2 to 6 inches; dark yellowish brown (10YR 3/4) gravelly loam, pale yellow (2.5Y 7/3) dry; weak very fine and fine granular and weak very fine and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, fine, medium, and coarse roots; common very fine and fine tubular and irregular pores; 20 percent gravel; moderately acid (pH 5.6); clear smooth boundary.
E2--6 to 11 inches; olive brown (2.5Y 4/4) gravelly loam, pale yellow (2.5Y 7/3) dry; weak very fine and fine subangular blocky and weak very fine and fine granular structure; slightly hard, friable, moderately sticky and slightly plastic; common very fine, fine, medium, and coarse roots; common very fine and fine tubular and irregular pores; 20 percent gravel, 5 percent cobbles; moderately acid (pH 5.6); clear wavy boundary. (Combined thickness of the E horizon is 4 to 11 inches.)
Bt/E1--11 to 17 inches; 65 percent dark yellowish brown (10YR 4/4) (Bt) and 35 percent olive brown (2.5Y 4/3) pale yellow (2.5Y 7/3) dry (E) gravelly clay loam; weak very fine, fine, and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine and fine and few medium and coarse roots; common very fine and fine tubular and irregular pores; few faint clay films on faces of peds and lining pores; 20 percent gravel, 5 percent cobbles; moderately acid (pH 5.8); clear wavy boundary.
Bt/E2--17 to 23 inches; 55 percent brown (10YR 4/3) (Bt) and 45 percent light olive brown (2.5Y 5/3) pale yellow (2.5Y 7/3) dry (E) gravelly clay loam; weak fine, medium, and coarse subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine and fine roots; few very fine and fine tubular and irregular pores; few distinct clay films on faces of peds and lining pores; few fine distinct strong brown (7.5YR 4/6) irregularly shaped masses of iron accumulation with clear boundaries in the matrix; 15 percent gravel; moderately acid (pH 6.0); clear wavy boundary.
Bt/E3--23 to 31 inches; 80 percent olive brown (2.5Y 4/3) (Bt) and 20 percent light olive gray (5Y 6/2) pale yellow (5Y 8/3) dry silty clay; moderate medium and coarse subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine roots; few very fine and fine tubular and irregular pores; common distinct clay films on faces of peds and lining pores; few fine distinct strong brown (7.5YR 4/6) irregularly shaped masses of iron accumulation with clear boundaries in the matrix; 10 percent gravel; slightly acid (pH 6.2); clear wavy boundary. (Combined thickness of the Bt/E horizon is 14 to 20 inches.)
Bt1--31 to 41 inches; olive brown (2.5Y 4/3) silty clay; moderate medium and coarse subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine tubular and irregular pores; many distinct clay films on faces of peds and lining pores; few fine distinct strong brown (7.5YR 4/6) irregularly shaped masses of iron accumulation with clear boundaries in the matrix; common fine and medium distinct olive (5Y 5/3) irregularly shaped iron depletions with clear boundaries in the matrix; 10 percent gravel; slightly acid (pH 6.4); clear wavy boundary. (6 to 12 inches thick)
2Bt2--41 to 55 inches; olive brown (2.5Y 4/3) gravelly silty clay; moderate medium and coarse angular blocky structure; very hard, very firm, very sticky and moderately plastic; few very fine irregular pores; many distinct dark yellowish brown (10YR 3/4) clay films on faces of peds and lining pores; 15 percent gravel; neutral (pH 6.6); clear wavy boundary.
2Bt3--55 to 62 inches; olive brown (2.5Y 4/3) gravelly silty clay; moderate medium and coarse angular blocky structure; very hard, very firm, very sticky and moderately plastic; common distinct dark brown (10YR 3/3) dry clay films on faces of peds and lining pores; 20 percent gravel; neutral (pH 6.8).
TYPE LOCATION: Clallam County, Washington, about 3.75 miles northeast of Dirty Face Ridge, about 2,510 feet east and 530 feet south of the northwest corner of Section 11, T. 28 N., R. 3 W. (Latitude 47 degrees, 56 minutes, 21 seconds N., Longitude 123 degrees, 01 minutes, 25 seconds W.)
RANGE IN CHARACTERISTICS: Mean annual soil temperature is 43 to 45 degrees F. The mean summer soil temperature is 45 to 47 degrees F. The mean winter soil temperature is 40 to 44 degrees F. These soils are usually moist, and are dry 30 to 45 consecutive days in the soil moisture control section. The particle-size control section has 5 to 30 percent rock fragments by volume and average clay content of 35 to 50 percent. Depth to the glossic horizon is 4 to 11 inches. Depth to redox concentrations is 10 to 20 inches. Depth to the 2Bt horizon is 24 to 40 inches. A perched water table is present above the 2Bt horizon for 120 to 180 cumulative days. The soil to a depth of 40 inches has an estimated linear extensibility of 2 to 3 inches. Bulk density is 1.50 to 1.80 grams per cubic centimeter.
The E horizon has hue of 10YR or 2.5Y moist and dry, value of 3 or 4 moist and 6 or 7 dry, and chroma of 3 or 4 moist and 2 or 3 dry.
The Bt/E horizon for the Bt portion has hue of 10YR or 2.5Y moist and dry, value of 6 or 7 dry, and chroma of 3 or 4 moist and dry. The E portion has hue of 2.5Y or 5Y moist and dry, value of 4 through 6 moist and 6 through 8 dry, and chroma of 2 or 3 moist and 1 through 3 dry. It is gravelly clay loam, silty clay, or gravelly silty clay loam. Texture of Bt and E material are the same. Reaction is moderately or slightly acid. Albic materials comprise 15 to 50 percent of the horizon. It has 35 to 45 percent clay content.
The Bt and 2Bt horizon has hue of 2.5Y or 5Y moist and dry, value of 4 or 5 moist and 5 through 7 dry, and chroma of 1 through 3 dry. It is gravelly silty clay, silty clay, or clay. It has 40 to 50 percent clay content.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Silverhorn soils are on low relief, dissected uplands and have slopes of 30 to 60 percent. The soils formed in colluvium and residuum from proglacial lake deposits. Elevations are 2,750 to 3,500 feet. Average annual precipitation ranges from 40 to 70 inches. Average annual temperature is 41 to 43 degrees F. The frost-free season is 130 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ayock, Bungalow, Mueller, and Tylerpeak soils. Ayock soils are on low relief, dissected uplands and are loamy-skeletal. Bungalow, Mueller, and Tylerpeak soils are on mountain slopes and are well drained.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow permeability. The Silverhorn soils have a perched zone of saturation between 1.0 and 3.0 feet from November through April; 120 to 180 cumulative days.
USE AND VEGETATION: Timber production, wildlife habitat, recreation, and watershed. Native vegetation is western hemlock, western redcedar, Pacific silver fir, Douglas-fir, Pacific rhododendron, northern twinflower, vine maple, bunchberry dogwood, and deerfoot vanillaleaf.
DISTRIBUTION AND EXTENT: Clallam County, Washington; MLRA 3. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Clallam County, Washington, 2000; Olympic National Forest.
REMARKS: Diagnostic horizons and features recognized in this pedon are the following:
Ochric epipedon
Albic horizon - 2 to 11 inches (E1 and E2 horizons)
Glossic horizon - 11 to 31 inches (Bt/E1, Bt/E2 and Bt/E3 horizons)
Argillic horizon - 11 to 62 inches (Bt/E1, Bt/E2, Bt/E3, Bt, 2Bt1, and 2Bt2 horizons)
Oxyaquic feature - perched water table is at its highest depth between the months of November through April and is present for 120 to 180 cumulative days.
PSCS - zone from 11 to 31 inches (Bt/E1, Bt/E2, and Bt/E3 horizons)
The soils formed in relic proglacial lake deposits in a wetter environment. The presence of the albic materials and redox features in the upper most horizons were not formed from present day pedogenesis.
Depth to diagnostic horizons and other features are measured from the top of the first mineral horizon. Based on the color combinations in the glossic horizon some pedons will also meet aquic subgroup criteria and are considered taxadjuncts.