LOCATION ELWELL WAEstablished Series
TAXONOMIC CLASS: Medial, ferrihydritic, frigid Aquic Durudands
TYPICAL PEDON: Elwell silt loam - woodland. (Colors are for moist soil unless otherwise noted. Textures are apparent field textures.)
01--2 to 1 inch; leaves, needles, and twigs.
O2--1 inch to 0; decomposed mat of leaves, needles, and twigs.
A--0 to 2 inches; black (10YR 2/1) silt loam, very dark brown (10YR 2/2) dry; moderate fine granular structure; slightly hard, friable, slightly sticky, slightly plastic and weakly smeary; many fine, medium, and coarse roots; many fine tubular pores; extremely acid (pH 4.2); abrupt smooth boundary. (0 to 8 inches thick)
Bsl--2 to 8 inches; strong brown (7.5YR 5/6) silt loam, reddish yellow (7.5YR 6/6) dry; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic and weakly smeary; many fine, medium, and coarse roots; few fine tubular pores; 5 percent pebbles; 5 percent iron concretions; strongly acid (pH 5.2); gradual wavy boundary. (2 to 10 inches thick)
Bs2--8 to 14 inches; brown (7.5YR 5/4) silt loam, light brown (7.5YR 6/4) dry; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic and weakly smeary; common medium and coarse roots; few fine tubular pores; 5 percent pebbles; 5 percent concretions; strongly acid (pH 5.2); gradual wavy boundary. (2 to 10 inches thick)
Bs3--14 to 23 inches; yellowish brown (10YR 5/6) silt loam, yellow (10YR 7/6) dry; few fine faint brownish yellow (10YR 6/6) mottles, yellow (10YR 8/6) dry; weak medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic and weakly smeary; few fine medium and coarse roots; few fine tubular pores; 10 percent pebbles, strongly acid (pH 5.2); abrupt smooth boundary. (0 to 14 inches thick)
BC--23 to 27 inches; pale olive (5Y 6/4) gravelly fine sandy loam, pale yellow (5Y 7/4) dry; many large distinct dark yellowish brown (10YR 4/4) mottles, light yellowish brown (10YR 6/4) dry; weak medium platy structure; hard, firm, slightly sticky, slightly plastic and weakly smeary; few fine tubular pores; 20 percent pebbles; strongly acid (pH 5.4); abrupt smooth boundary. (0 to 13 inches thick)
Bsm--27 inches; olive (5Y 5/3) gravelly sandy loam, pale olive (5Y 6/3) dry; massive; very hard, very firm, nonsticky and nonplastic; weakly cemented; 20 percent pebbles; moderately acid (pH 5.6).
TYPE LOCATION: Snohomish County, Washington; approximately seven miles northeast of Arlington; 2,640 feet north and 1,570 feet west of the southeast corner of sec. 27, T. 31 N., R. 7 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature at a depth of 20 inches ranges from 45 to 47 degrees F. Depth to the pan ranges from 20 to 40 inches. Coarse fragments in the series control section ranges from 5 to 35 percent.
The A horizon has hue of 10YR or 7.5YR, value of 2 through 4 moist, 4 through 6 dry, and chroma of 1 through 4 moist and dry. It has weak fine subangular blocky or weak fine granular structure. Some pedons have an E horizon with hue of 10YR or 7.5YR, value of 4 or 5 moist, 6 dry, and chroma of 1 to 3 moist or dry. Reaction is moderately acid to extremely acid.
The Bs horizon has hue of 10YR, 7.5YR, or 5YR, value of 3 through 6 moist, 4 through 7 dry, and chroma of 2 through 8 moist and dry. It is silt loam, loam, gravelly silt loam, or gravelly loam with 5 to 35 percent pebbles. Reaction is strongly acid or moderately acid.
The Bsm horizon has hue of 10YR, 2.5Y or 5Y, value of 4 through 6 moist, 5 through 8 dry, and chroma of 2 through 4 moist or dry. It is gravelly loamy sand, gravelly fine sandy loam, gravelly sandy loam, very gravelly loam, or gravelly loam with 5 to 40 percent pebbles.
COMPETING SERIES: These are the Getchell, Potchub, Tokul, and Verlot series in other families. Getchell, Potchub, and Verlot soils are cryic. Tokul soils are mesic.
GEOGRAPHIC SETTING: Elwell soils are on mountain slopes and plateaus at elevations ranging from 800 to 2,500 feet. Slopes are 3 to 90 percent. The soils formed in glacial till and volcanic ash. The till was derived from a wide variety of rock. Elwell soils are in a cool marine climate with cool, dry summers and cool, wet winters. The mean annual precipitation ranges from 60 to 80 inches. The mean January temperature is 29 degrees F; mean July temperature is 59 degrees F; and the mean annual temperature is 45 degrees F. The frost-free season is 120 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Oakes, Ogarty, Olomount, Oso, Philippa, Pitcher, Saxon and Skykomish soils and the competing Getchell and Tokul soils. Oakes and Skykomish soils have more than 35 percent coarse fragments in the 10- to 40-inch control section and are deeper than 40 inches. Ogarty soils have a mean annual temperature of more than 47 degrees F. Ogarty, Olomount and Oso soils have bedrock at a depth of 20 to 40 inches. Saxon soils are fine-silty. Philippa soils have more than 35 percent coarse fragments in the control section.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow or medium runoff; moderate permeability to the duripan and very slow in the duripan. A perched water table is as high as 1.5 to 3 feet at times from November through June.
USE AND VEGETATION: Used for woodland and wildlife habitat. Native vegetation is western hemlock, Douglas-fir, red alder, western redcedar, with an understory of western swordfern, red huckleberry, western brackenfern, deer fern, salal, ladyfern, Oregon-grape, devilsclub, and trailing blackberry.
DISTRIBUTION AND EXTENT: West slopes of the Cascade Mountains in northwestern Washington. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Snohomish County, Washington, 1979.
REMARKS: Classification only changed 4/94 because of recent amendments to Soil Taxonomy. Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the mineral surface to 2 inches, and a horizon from 2 to 27 inches with andic soil properties.