LOCATION WHATCOM WAEstablished Series
TAXONOMIC CLASS: Fine-loamy, isotic, mesic Aqualfic Haplorthods
TYPICAL PEDON: Whatcom silt loam - on a 2 percent south-facing slope in pasture at 180 feet elevation. (Colors are for moist soil unless otherwise noted. All textures are apparent field textures.)
Ap--0 to 9 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; weak fine granular structure; soft, very friable, nonsticky, nonplastic; weakly smeary; many very fine and common fine roots; many very fine irregular pores; 5 percent pebbles and 2 percent concretions; NaF pH 10.5; moderately acid (pH 6.0); abrupt smooth boundary. (3 to 9 inches thick)
Bs1--9 to 13 inches; dark brown (7.5YR 4/4) silt loam, light brown (7.5YR 6/4) dry; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic, weakly smeary; many very fine roots; many very fine irregular pores; 5 percent pebbles and 1 percent concretions; NaF pH 11.5; moderately acid (pH 6.0); clear smooth boundary.
Bs2--13 to 16 inches; dark brown (7.5YR 3/4) silt loam, light brown (7.5YR 6/4) dry; weak fine subangular blocky structure; soft, very friable; nonsticky, nonplastic, weakly smeary; many very fine roots; many very fine irregular pores; 5 percent pebbles and 1 percent concretions; NaF pH 12.0; moderately acid (pH 6.0); abrupt smooth boundary. (Combined thickness of the Bs horizon is 6 to 23 inches)
2Bt1--16 to 20 inches; light olive brown (2,5Y 5/4) loam, pale yellow (2.5Y 7/4) dry; many medium prominent mottles of dark yellowish brown (10YR 4/4), yellowish brown (10YR 5/4) dry; medium thick platy structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine roots; many very fine irregular pores; few, thin patchy clay films on faces of peds; 5 percent pebbles; NaF pH 9.8; moderately acid (pH 6.0); clear smooth boundary.
2Bt2--20 to 26 inches; light olive brown (2.5Y 5/4) loam, light gray (2.5Y 7/2) dry; many coarse prominent mottles of yellowish brown (10YR 5/6), reddish yellow (7.5YR 6/6) dry; moderate thick platy structure; slightly hard, friable, nonsticky, slightly plastic; few very fine roots; many very fine irregular pores; few, thin patchy clay films on faces of peds; 10 percent pebbles; NaF pH 10.0; moderately acid (pH 6.0); abrupt smooth boundary. (Combined thickness of the 2BC horizon is 7 to 15 inches)
2C1--26 to 35 inches; light olive gray (5Y 6/2) loam, white (5Y 8/2) dry; many medium prominent mottles of light olive brown (2.5Y 5/6) moist and dry; moderate thick platy structure; very hard, firm, slightly sticky, slightly plastic; common very fine irregular pores; 5 percent pebbles; NaF pH 9.4: neutral (pH 6.6); clear smooth boundary. (5 to 25 inches thick)
2C2--35 to 60 inches; dark gray (5Y 4/1) loam, light gray (5Y 7/1) dry; moderate thick blocky structure; extremely hard, very firm, slightly sticky, slightly plastic; very few very fine irregular pores; 5 percent pebbles; NaF pH 9.6; mildly alkaline (pH 7.6); slightly effervescent.
TYPE LOCATION: Whatcom County, Washington; about 7 miles northeast of Bellingham; 20 feet north and 600 feet east of the southwest corner of sec. 30, T. 39 N., R. 4 E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature is 50 to 54 degrees F. These soils are usually moist, but are dry for 45 to 60 consecutive days following the summer solstice. Thickness of volcanic ash influence and depth to the 2B horizon is 14 to 28 inches. By weighted average, the upper part of the control section has 0 to 10 percent pebbles, and the lower part has 5 to 25 percent. Clay content in the lower part of the control section ranges from 18 to 30 percent by weighted average.
The A horizon has hue of 7.5YR or 10YR, value of 3 or 4 moist, 4 or 5 dry, and chroma of 2 through 4 moist, 3 or 4 dry. Reaction is moderately acid or slightly acid.
The Bs horizon has hue of 7.5YR or 10YR, value of 3 or 4 moist, 5 or 6 dry, and chroma of 4 through 6 moist and dry. Rock fragments range from 0 to 15 percent. Reaction is moderately acid or slightly acid.
The 2Bt 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. Rock fragments range from 35 to 25 percent, although individual horizons contain up to 35 percent. It is loam, gravelly loam, clay loam, gravelly clay loam, or silty clay loam, Reaction is moderately acid through neutral. Thin strata of sandy loam are in some pedons.
The 2C horizon has hue of 2.5Y or 5Y, value of 4 through 6 moist, 6 through 8 dry, and chroma of 1 or 2 moist and dry. Mottles, when present, have hue of 10YR or 2.5Y, value of 5 or 6 dry. Rock fragments range from 5 to 25 percent, although individual horizons contain up to 35 percent. It is loam, gravelly loam, clay loam, gravelly clay loam, or silty clay loam. Structure is blocky or the soil is massive. Reaction is neutral or mildly alkaline. Thin strata of sandy loam are in some pedons.
COMPETING SERIES: This is the Skipopa series in another family. Skipopa soils are in a fine family.
GEOGRAPHIC SETTING: Whatcom soils are on glaciomarine drift plains at elevations of 50 to 600 feet. They occupy the upland position in a kame-kettle type topography. Slopes are 0 to 60 percent. The soils formed in volcanic ash and loess over glaciomarine drift. Whatcom soils are in a marine climate with warm, dry summers and cool, moist winters. Snow cover is intermittent. Average annual precipitation is 35 to 55 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 150 to 190 days.
GEOGRAPHICALLY ASSOCIATED SOILS These are the Barneston, Birchbay, Kline, Labounty, Shalcar, Squalicum, Whitehorn, and Yelm soils. Barneston and Kline soils are sandy-skeletal. Birchbay soils are coarse-loamy over sandy or sandy-skeletal. Squalicum and Yelm soils are coarse-loamy. Labounty and Whitehorn soils have an aquic moisture regime and an umbric epipedon.
DRAINAGE AND PERMEABILITY: Moderately well drained; very slow to medium runoff; moderate permeability in the solum, slow in the substratum. A perched water table is as high as 1.5 to 3 feet at times from December to April.
USE AND VEGETATION: Used mainly for woodland, cropland, and homesites. Hay and pasture are common crops. Native vegetation is Douglas-fir, western hemlock, red alder, bigleaf maple, paper birch, and western redcedar, with an understory of vine maple, red huckleberry, salal, western swordfern, Oregon-grape, western brackenfern, salmonberry, sweetscented bedstraw, and trailing blackberry.
DISTRIBUTION AND EXTENT: Northwestern Washington. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Whatcom County, Washington, 1910.
REMARKS: This draft reflects a change in classification from medial over loamy, mixed, mesic Aquic Xerochrepts to fine-loamy, mixed, mesic Aqualfic Haplorthods. Characterization data are available on these soils. Laboratory number S81WA-073-7. Partial laboratory data are also available under laboratory numbers S81WA-073-19 through S81WA-073-21. Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the surface to 9 inches and a spodic horizon from 9 to 16 inches, and an argillic horizon from 16 to 26 inches.