LOCATION ALDERWOOD WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, mesic Vitrandic Dystroxerepts
TYPICAL PEDON: Alderwood gravelly ashy sandy loam - forested. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 7 inches; very dark grayish brown (10YR 3/2) gravelly ashy sandy loam, brown (10YR 5/3) dry; moderate fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many fine roots; few fine irregular pores; slightly acid (pH 6.2); abrupt smooth boundary. (3 to 7 inches thick)
Bw1--7 to 21 inches; dark yellowish brown (10YR 4/4) very gravelly ashy sandy loam, yellowish brown (10YR 5/4) dry; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many fine roots; many fine tubular and irregular pores; 35 percent gravel; diffuse smooth boundary; slightly acid (pH 6.2).
Bw2--21 to 30 inches; brown (10YR 4/3) very gravelly ashy sandy loam, pale brown (10YR 6/3); dry; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common fine roots; few very fine tubular pores; 40 percent gravel; slightly acid (pH 6.2); clear wavy boundary. (Combined Bw1 and Bw2 horizons are 15 to 30 inches thick)
2Bg--30 to 35 inches; 50 percent olive brown (2.5Y 4/4) very gravelly sandy loam, light yellowish brown (2.5Y 6/4) dry and 50 percent dark grayish brown (2.5Y 4/2) iron-mangenese nodules with strong brown (7.5YR 5/6) coatings on fragments, light brownish gray (2.5Y 6/2) and reddish yellow (7.5YR 6/6) dry; massive; slightly hard, very friable, nonsticky and nonplastic; few fine roots; common fine tubular and interstitial pores; 45 percent gravel; moderately acid (pH 6.0); abrupt wavy boundary. (0 to 15 inches thick)
2Cd1--35 to 43 inches; dark grayish brown (2.5Y 4/2) very gravelly sandy loam, light brownish gray (2.5Y 6/2) dry; dark yellowish brown (10YR 4/4), olive (5Y 4/4), yellowish red (5YR 4/6) and strong brown (7.5YR 5/6) in cracks; massive; extremely hard; extremely firm, nonsticky and nonplastic; few fine roots; few fine tubular pores; 40 percent gravel; moderately acid (pH 6.0); abrupt irregular boundary. (5 to 20 inches thick)
2Cd2--43 to 60 inches; grayish brown (2.5Y 5/2) dense glacial till that breaks to very gravelly sandy loam, light gray (2.5Y 7/2) dry; massive; extremely hard, extremely firm, nonsticky and nonplastic; 40 percent gravel; moderately acid (pH 6.0).
TYPE LOCATION: Snohomish County, Washington; about 5 miles east of Lynnwood on Maltby road; 200 feet south and 400 feet east of the center of sec. 28. T. 27 N., R. 5 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is estimated to range from 47 to about 55 degrees F. These soils are usually moist, but are dry between depths of 8 and 24 inches for 60 to 75 consecutive days in the summer in most years. The soil is strongly acid to slightly acid above the 2Cd1 horizon and slightly acid or moderately acid in the 2Cd1 horizon. Depth to 2Cd1 horizon is 20 to 40 inches. Rock fragments in the particle-size control section range from 35 to 50 percent total including 35 to 50 percent gravel and 0 to 10 percent cobbles.
The A horizon has hue of 10YR or 7.5YR, value of 2 or 3 moist, 3 through 5 dry, and chroma of 2 to 4. It has weak or moderate granular structure. Some pedons have an E horizon less than 1 inch thick.
The Bw1 and Bw2 horizons have hue of 10YR or 7.5YR, and value and chroma of 2 through 6 dry or moist. It is very gravelly loam or very gravelly sandy loam and has weak or moderate blocky structure. The Bw1 is gravelly loam in some pedons. This horizon contains none to many hard concretions presumed to be of iron and manganese compounds.
The 2Bg horizon, or the 2BC or 2CB horizon has hue of 10YR or 2.5Y, value of 5 through 7 dry, and chroma of 2 through 4 moist and dry. They have redox concentrations in some pedons, but lack depletions of 2 or lower chroma within 30 inches of the surface. These horizons are very gravelly sandy loam or very gravelly loam. They have weak subangular blocky structure or are massive.
The 2Cd horizons (densic layers) have hues of 10YR or 2.5Y, value of 4 through 8 dry, and chroma of 1 through 3 moist and dry and are mottled in some pedons. It is very gravelly sandy loam, very gravelly loamy sand, gravelly sandy loam, or gravelly loamy sand when crushed.
COMPETING SERIES: These are the Baldhill, Neausite, Dabob, Fidalgo, and Whistle series. The Baldhill soils are very deep and lack densic materials. The Beaustie and Fidalgo soils are 20 to 40 inches deep to a lithic contact. The Whistle soils are 40 to 60 inches deep to a lithic contact. Dabob soils have an albic horizon and lack densic materials within 60 inches.
GEOGRAPHIC SETTING: These soils are on till plains and moraines at elevations of 0 to about 800 feet. Slope is 0 to 65 percent. The soils formed in glacial till. Alderwood soils are in a cool marine climate. The summers are cool and dry, and the winters are mild and wet. Mean annual precipitation ranges from 25 to 60 inches, most of which falls as rain from November through March. Mean January temperature is 38 degrees F, mean July temperature is 60 degrees F, and mean annual temperature is 50 degrees F. The growing season (28 degrees F) is about 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Beausite, Dick, Everett, Hoogdal, Indianola, Kitsap, Norma, Quilcene, Skipopa and Whidbey series. All of these soils except Whidbey soils lack a densic layer within 40 inches. In addition, the Beausite soils have a lithic contact at 20 to 40 inches. Dick, Hoogdal, Indianola, Kitsap, and Skipopa soils have less than 35 percent coarse fragments. Everett soils are sandy-skeletal. McKenna soils have an aquic moisture regime. Norma soils have an aquic moisture regime of less than 35 percent coarse fragments in the upper part of the control section. Quilcene soils are in a fine family. Whidbey soils have an E horizon 2 to 5 inches thick and have a higher base status.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow to medium runoff; moderately rapid permeability to the densic layer and very slow permeability below. A perched water table is as high as 18 to 36 inches at times from January through March.
USE AND VEGETATION: Used mostly for woodland, field crops, hay and pasture, orchards, vineyards, wildlife habitat, watershed, and non-farm uses. The native vegetation is Douglas-fir, western hemlock, western redcedar, and red alder with an understory of salal, Oregon-grape, western brackenfern, western swordfern, Pacific rhododendron, huckleberry, red huckleberry, evergreen huckleberry, and Orange honeysuckle.
DISTRIBUTION AND EXTENT: Northwestern Washington; MLRA 2. The series is extensive.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Snohomish County, Washington 1936.
REMARKS: Classification only changed 4/94 because of recent amendments to Soil Taxonomy, except the horizon nomenclature was updated, and fragments of ortstein and ortstein were changed to iron-mangenese nodules and a densic layer. Classification changed 1/2000 from mixed, mesic Vitrandic Durochrepts to isotic, mesic Vitrandic Dystroxerepts based on revision to Soil Taxonomy. Diagnostic horizons and features include:
Ochric epipedon
Cambic horizon - from 7 to 35 inches
Densic material - from 43 to 60 inches
Vitrandic feature - assumed to be from 0 to 30 inches
Oxyaquic feature - perched water table at 18 to 36 inches at times from January to March.
All depths to diagnostic horizons and features noted in the range of characteristics are measured from the top of the first mineral horizon.
More investigation is needed to differentiate the Alderwood from the Dabob series.
ADDITIONAL DATA: Partial data available for this series. Sample # S71WA-033-002, Riverside Lab., 11/73.