LOCATION STEQUATEHO WAEstablished Series
TAXONOMIC CLASS: Medial, mixed, isomesic Aquic Fulvudands
TYPICAL PEDON: Stequateho gravelly medial loam - forestland on a 2 percent westerly aspect at an elevation of 380 feet in a western hemlock/Alaska huckleberry-salal plant association. (When described on December 11, 1997, the soil was moist throughout. Colors are for moist soil unless otherwise stated. All textures are apparent field textures.)
Oi-- 0 to 1 inch; slightly decomposed needles, leaves, twigs, and cone fragments; abrupt smooth boundary. (0.5 to 2 inches thick)
Oe-- 1 to 2 inches; intermediately decomposed organic materials; many very fine, fine, medium, and coarse roots; abrupt smooth boundary. (0 to 4 inches thick)
Oa-- 2 to 7 inches; highly decomposed organic materials; many very fine and fine and common medium and coarse roots; abrupt smooth boundary. (1 to 6 inches thick)
A-- 7 to 10 inches; 65 percent dark brown (7.5YR 3/3) gravely medial loam, brown (7.5YR 4/3) dry and 35 percent strong brown (7.5YR 4/6), reddish yellow (7.5YR 6/6) dry; weak very fine, fine, and medium subangular blocky and weak very fine and fine granular structure; slightly hard and hydrophobic when dry, friable, slightly sticky and slightly plastic; weakly smeary; common very fine, fine, medium, and coarse roots; common very fine and fine tubular and irregular pores; 15 to 20 percent gravel; very strongly acid (pH 4.6); clear smooth boundary. (2 to 4 inches thick)
Bw1-- 10 to 17 inches; dark yellowish brown (10YR 4/6) gravelly medial loam, brownish yellow (10YR 6/6) dry; moderate very fine, fine, and medium subangular blocky and weak very fine and fine granular structure; slightly hard, friable, moderately sticky and slightly plastic; weakly smeary; few very fine, fine, medium, and coarse roots; few very fine and fine tubular and irregular pores; 20 percent gravel; very strongly acid (pH 4.8); clear wavy boundary.
Bw2-- 17 to 23 inches; dark yellowish brown (10YR 4/6) medial loam, brownish yellow (10YR 6/6) dry; moderate very fine, fine, and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; few very fine, fine, medium, and coarse roots; few very fine and fine tubular and irregular pores; 10 percent gravel; very strongly acid (pH 5.0); clear wavy boundary.
Bw3-- 23 to 34 inches; strong brown (7.5YR 4/6) medial silt loam, strong brown (7.5YR 5/6) dry; moderate very fine, fine, and medium subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; weakly smeary; few very fine, fine, medium, and coarse roots; few very fine and fine tubular and irregular pores; 5 percent gravel; very strongly acid (pH 4.8); clear wavy boundary.
Bw4-- 34 to 39 inches; strong brown (7.5YR 4/6) medial silty clay loam, strong brown (7.5YR 5/6) dry; moderate very fine, fine, and medium subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; weakly smeary; few very fine and fine roots; few very fine and fine tubular and irregular pores; 5 percent gravel; very strongly acid (pH 5.0); clear wavy boundary.
Bw5-- 39 to 48 inches; strong brown (7.5YR 4/6) medial silty clay loam, strong brown (7.5YR 5/6) dry; moderate very fine, fine, and medium subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; weakly smeary; few very fine roots; few very fine and fine tubular and irregular pores; few fine distinct light olive brown (2.5Y 5/3), light yellowish brown (2.5Y 6/3) dry irregularly shaped iron depletions with clear boundaries in the matrix; 5 percent gravel; very strongly acid (pH 5.0); clear wavy boundary. (Combined thickness of the Bw horizon is 36 to 48 inches thick.)
2C-- 48 to 67 inches; dark yellowish brown (10YR 3/4) extremely gravelly sandy loam, yellowish brown (10YR 5/4) dry; weak very fine and fine subangular blocky structure; slightly hard, friable, slightly sticky an slightly plastic; 70 percent gravel, 5 percent cobbles; strongly acid (pH 5.2).
TYPE LOCATION: Grays Harbor County, Washington, about 2 3/4 miles north-northwest of the intersection of State Highway 101 and Forest Service road #21, about 1,935 feet north and 2,510 feet west of the southeast corner of Section 4, T. 23 N., R. 10 W. (Latitude 47 degrees 31 minutes 29 seconds N., Longitude 124 degrees 07 minutes 12 seconds W.)
RANGE IN CHARACTERISTICS: Mean annual soil temperature is 47 to 50 degrees F. The difference between the mean summer and mean winter soil temperature is 4 to 7 degrees F. These soils are usually moist, and are dry less than 45 consecutive days in the soil moisture control section. Depth to glaciofluvial deposits (2C horizon) is 40 to 50 inches. Depth to the redox features is 30 to 40 inches. The particle-size control section has andic soil properties throughout, and 0 to 25 percent rock fragments by volume. The andic soil material has an estimated moist bulk density of 0.75 to 0.90 g/cc, acid-oxalate extractable aluminum plus one half of the acid-oxalate extractable iron of 2 to 4 percent, phosphate retention of 85 to 100 percent, and 15-bar water retention of 25 to 35 percent for air dried samples, acid oxalate iron is 0.5 to 1.5 percent, and over 2 cmol/kg of aluminum. The particle-size control section has 20 to 35 percent field estimated clay and 10 to 40 percent sand.
The A horizon has hue of 7.5YR or 10YR moist and dry, value of 3 or 4 moist and 4 through 6 dry, and chroma of 3, 4, or 6 moist and dry. It has 10 to 20 percent organic matter.
The Bw horizon has hue of 10YR or 7.5YR moist and dry, value of 4 or 5 moist and 5 or 6 dry, and chroma of 4 or 6 moist and dry. It is gravelly medial loam, medial loam, medial silt loam, or medial silty clay loam. Reaction is very strongly acid or strongly acid. It has 2 to 12 percent organic matter decreasing to less than 7 percent within 20 inches of the mineral soil surface.
The 2C horizon has hue of 10YR or 2.5Y, value of 3 or 4 moist and 5 or 6 dry, and chroma of 3 or 4 moist and 4 or 6 dry. It is extremely gravelly sandy loam or very gravelly sandy loam. Reaction is very strongly acid or strongly acid.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Stequateho soils are on glacial outwash terraces. Slopes are 0 to 10 percent. The soils formed in alluvium over glacial outwash. Elevations are 350 to 470 feet. Mean annual precipitation is 115 to 130 inches. Fog drip contributes to the effective precipitation totals. Mean annual temperature is 46 to 48 degrees F. The frost-free season is 140 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These soils are the Haas, Kunamakst, Manorcreek, and Salmonriver. Haas, Kunamakst, and Salmonriver soils are on ground moraines and have an isofrigid soil temperature regime. Manorcreek soils are in closed wet depressions and are organic soils and are very poorly drained soils.
DRAINAGE AND PERMEABILITY: Moderately well drained; moderate permeability. Stequateho soils have a seasonal zone of saturation between 2.5 and 5.0 feet from November through April.
USE AND VEGETATION: Timber production, wildlife habitat, recreation, and watershed. Native vegetation is western hemlock, salal, Alaska huckleberry, red huckleberry, and deer fern.
DISTRIBUTION AND EXTENT: Grays Harbor County, Washington; MLRA 4A. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Grays Harbor County, Washington, 2007; Quinault Indian Reservation.
REMARKS: Diagnostic horizons and features recognized in this pedon are the following:
- Folistic epipedon
- Ochric epipedon
- Cambic horizon - 10 to 48 inches (Bw1 through Bw5 horizons)
- Andic soil properties - 7 to 48 inches (A and Bw1 through Bw5 horizons)
- Aquic conditions - 39 to 48 inches (Bw5 and C horizons)
- PSCS - 7 to 47 inches (A and Bw1 through Bw5 horizons)
- All depths to diagnostic horizons and features are measured from the top of the first mineral horizon.