LOCATION WHITEHORN WAEstablished Series
TAXONOMIC CLASS: Fine-loamy, isotic, mesic Aquandic Endoaqualfs
TYPICAL PEDON: Whitehorn silt loam - on a 1 percent southeast-facing slope in grass pasture at 150 feet elevation. (Colors are for moist soil unless otherwise noted. All textures are apparent field textures).
Ap--0 to 10 inches; very dark brown (10YR 2/2) silt loam, dark grayish brown (10YR 4/2) dry; moderate fine granular structure; hard, friable, slightly sticky, slightly plastic; many very fine and fine roots; many very fine irregular pores; NaF pH 9.4: moderately acid (pH 5.6); abrupt wavy boundary. (8 to 12 inches thick)
AB--10 to 14 inches; dark brown (10YR 3/3) loam, grayish brown (10YR 5/2) and light brownish gray (10YR 6/2) dry; many fine distinct mottles of dark yellowish brown (10RY 3/6) and 10YR 4/6), yellowish brown (10YR 5/6) dry; moderate medium subangular blocky structure; hard, friable, slightly sticky, slightly plastic; common very fine and fine roots; many very fine irregular pores; NaF pH 9.4; moderately acid (pH 5.8); clear wavy boundary. (0 to 4 inches thick).
BAg--14 to 18 inches; dark grayish brown (10YR 4/2) and light olive brown (2,5Y 5/4) very fine sandy loam, light gray (10YR 7/2) and light yellowish brown (10YR 6/4) dry; many coarse prominent mottles of dark yellowish brown (10YR 3/4) and strong brown (7.5YR 4/6), brownish yellow (10YR 6/6) dry; moderate medium subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine and fine roots; many very fine irregular pores; 5 percent pebbles; slightly acid (pH 6.4); clear wavy boundary. (4 to 19 inches thick)
Bg--18 to 26 inches; dark brown (10YR 4/3) and grayish brown (10YR 5/2) very gravelly sandy loam, pale brown (10YR 6/3) and light gray (10YR 7/2) dry; many coarse prominent mottles of dark yellowish brown (10YR 4/6), brownish yellow (10YR 6/6) and reddish yellow (7.5YR 6/6) dry; weak fine subangular blocky structure; hard, friable, nonsticky and nonplastic; few very fine and fine roots; many very fine irregular pores; 35 percent pebbles; slightly acid (pH 6.4); abrupt wavy boundary. (8 to 16 inches thick)
Btg--26 to 33 inches; olive brown (2.5Y 4/4) and grayish brown (2.5Y 5/2) loam, light yellowish brown (10YR 6/4) and light gray (2.5Y 7/2) dry; many medium prominent mottles of dark yellowish brown (10YR 4/6), brownish yellow (10YR 6/6) dry; massive; very hard, firm, slightly sticky and slightly plastic; 5 percent pebbles; neutral (pH 6/8); clear wavy boundary. (6 to 12 inches thick)
2C--33 to 60 inches; olive brown (2.5Y 4/4) and brown (10YR 5/3) silt loam, very pale brown (10YR 7/3) and light gray (2.5Y 7/2) dry; common fine prominent mottles of dark yellowish brown (10YR 4/6 and 10YR 3/4), brownish yellow (10YR 6/6) dry; massive; very hard, very firm, slightly sticky and slightly plastic; 5 percent pebbles; neutral (pH 7.0).
TYPE LOCATION: Whatcom County, Washington; about 3 miles west of Ferndale; 1,000 feet south and 200 feet east of the northwest corner of sec. 35, T. 39 N., R. 1 E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature is 50 to 54 degrees F. Thickness of the solum is 20 to 40 inches. Depth to the Btg is 16 to 24 inches. By weighted average, the particle-size control section has 10 to 18 percent clay and 0 to 15 percent pebbles, although the Bg2 horizon contains 0 to 40 percent pebbles.
The A and AB horizons have hue of 7.5YR or 10YR, value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. Structure is weak or moderate. The A horizon is mottled in some pedons. Reaction is strongly acid or moderately acid.
The BAg horizon has hue of 10YR or 2.5Y, value of 4 through 6 moist, 5 through 7 dry, and chroma of 2 through 4 moist and dry. Structure is weak or moderate. Dry consistence is slightly hard or hard. Reaction is moderately acid or slightly acid. It is loam, silt loam, or very fine sandy loam.
The Bg horizon has hue of 10YR or 2.5Y, value of 4 or 5 moist, 6 or 7 dry, and chroma of 2 through 4 moist and dry. It is sandy loam, gravelly loam, gravelly sandy loam, or very gravelly sandy loam. Reaction is moderately acid or slightly acid.
The Btg and C horizons have hue of 10YR through 5Y, value of 4 through 6 moist, 6 through 8 dry, and chroma of 2 through 4 moist and dry. They are loam, silt loam, clay loam, or silty clay loam. Rock fragments range from 0 to 15 percent by weighted average. Reaction is slightly acid or neutral.
COMPETING SERIES: These are the Labounty and Lantz series. Labounty soils are loam or silt loam immediately above the argillic horizon. Lantz soils have an ochric epipedon.
GEOGRAPHIC SETTING: Whitehorn soils are in depressional areas in wave-reworked glaciomarine drift plains at elevations of 50 to 350 feet. Slopes are 0 to 2 percent. The soils formed in glaciofluvial deposits with an admixture of loess and volcanic ash over glaciomarine drift. Whitehorn soils are in a marine climate with warm dry summers and cool, moist winters. Snow cover is intermittent. Average annual precipitation is 30 to 40 inches, which falls mostly between October and May. Each of the summer months has at least one inch of rainfall. Mean January temperature is 36 degrees F; mean July temperature is 62 degrees F. The mean annual temperature is 50 degrees F. The frost-free season is 160 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Labounty soils and the Birchbay, Clipper, Hale, Kickerville, Whatcom and Yelm soils. None of these soils except the Yelm soils and the competing Labounty soils have an aquic moisture regime. Birchbay soils are coarse-loamy over sandy or sandy-skeletal. Clipper soils have a xeric moisture regime and lack an argillic horizon. Hale soils are coarse-loamy over sandy or sandy skeletal. Kickerville and Yelm soils are medial.. Whatcom soils are coarse-loamy.
DRAINAGE AND PERMEABILITY: Poorly drained; very slow to ponded runoff; moderately slow permeability. The water table is as high as ponded to 1 foot below the surface at times during November through May, unless drained.
USE AND VEGETATION: Used for pasture, hayland, cropland, and woodland. Native vegetation is western redcedar, red alder, western hemlock, black cottonwood, and Douglas-fir, with an understory of salmonberry, western brackenfern, trailing blackberry, skunkcabbage, sweetscented bedstraw, red huckleberry, and western swordfern.
DISTRIBUTION AND EXTENT: Puget lowlands in northwestern Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Whatcom County, Washington, 1983.
REMARKS: This draft reflects a change in classification from coarse-loamy, mixed, mesic Typic Humaquepts to coarse-loamy, mixed, mesic Typic Umbraqualfs. Diagnostic horizons and features recognized in this pedon are an umbric epipedon from the surface to 14 inches and a glayed argillic horizon from 26 to 33 inches. The argillic horizon is assumed based on thin sections from the associated Whatcom and Labounty series.