LOCATION SKYKOMISH          WA
Established Series
Rev. MK/RJE
4/94

SKYKOMISH SERIES


The Skykomish series consists of deep, somewhat excessively drained soils formed in glacial outwash and volcanic ash. Skykomish soils are on outwash terraces and terrace escarpments and have slopes of 0 to 65 percent. The mean annual precipitation is about 60 inches and the average annual temperature is about 45 degrees F.

TAXONOMIC CLASS: Sandy-skeletal, mixed, frigid Typic Vitrixerands

TYPICAL PEDON: Skykomish gravelly loam - forested. (Colors are for moist soil unless otherwise noted. All textures are apparent field textures.)

Oi--4 to 3 inches; forest litter of leaves and twigs.

Oa--3 inches to 0; decomposed forest litter.

A--0 to 2 1/2 inches; dark reddish brown (5YR 3/3) gravelly loam, dark brown (7.5YR 4/4) dry; black (5YR 2/1) stains on 70 percent of ped surface; moderate coarse subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic, weakly smeary; common very fine, fine, medium and coarse roots; common very fine discontinuous pores; 17 percent rounded and angular pebbles; very strongly acid (pH 5.0); abrupt smooth boundary. (1 to 11 inches thick)

Bs1--2 1/2 to 12 inches; yellowish red (5YR 4/8) gravelly loam, light brown (7.5YR 6/4) dry; weak coarse subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic, weakly smeary; few very fine, fine, medium and coarse roots; common very fine discontinuous pores; 20 percent rounded and angular pebbles; medium acid (pH 6.0); clear wavy boundary. (5 to 13 inches thick)

Bs2--12 to 19 inches; yellowish red (5YR 4/6) very gravelly fine sandy loam, reddish yellow (7.5YR 6/6) dry; weak coarse subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic, weakly smeary; few very fine, fine and common medium and coarse roots; common very fine discontinuous pores; 40 percent rounded and angular pebbles; medium acid (pH 6.0); abrupt irregular boundary. (0 to 12 inches thick)

2C1--19 to 28 inches; dark yellowish brown (10YR 4/4) extremely gravelly loamy coarse sand, light yellowish brown (10YR 6/4) dry; single grain; loose; few very fine, fine and medium roots; 65 percent pebbles and 5 percent cobbles; very compact discontinuous 1- to 2-inch thick layer in upper part of horizon; medium acid (pH 6.0); abrupt wavy boundary. (3 to 40 inches thick)

2C2--28 to 60 inches; very dark grayish brown (10YR 3/2) extremely gravelly coarse sand, olive (5Y 5/3) dry; single grain; loose; 65 percent pebbles and 5 percent cobbles; medium acid (pH 6.0).

TYPE LOCATION: Snohomish County, Washington; 2,000 feet east and 2,150 feet south of northwest corner of sec. 35, T. 31 N., R. 7 E.

RANGE IN CHARACTERISTICS: The mean annual soil temperature at a depth of 20 inches is 44 to 47 degrees F. These soils are usually moist, but are dry in the moisture control section for 45 to 60 consecutive days following summer solstice. Solum thickness ranges from 14 to 31 inches, but loamy-skeletal material does not extend below a depth of 20 inches. The upper part of the particle-size control section averages 35 to 50 percent rock fragments and the lower part averages 50 to 80 percent rock fragments.

The A horizon has hue of 10YR or 7.5YR, value of 2 through 5 moist, 3 through 7 dry, and chroma of 1 through 4 moist and dry. Some pedons lack an A horizon and have an E horizon.

The matrix of the Bs horizons has hue of 5YR through 10YR, value of 3 through 5 moist, 4 through 6 dry and chroma of 3 through 8 moist and dry. Below 10 inches it is gravelly loam, very gravelly loam, very gravelly fine sandy loam, or very gravelly sandy loam. It is very gravelly loamy sand in the lower part in some pedons. Reaction is very strongly acid to medium acid.

The 2C horizon has hue of 10YR through 5Y, value of 3 through 6 moist, 3 through 7 dry, and chroma of 2 through 6 moist, 3 through 6 dry. It ranges from extremely gravelly coarse sand to very gravelly loamy sand.

COMPETING SERIES: These are the Colton, Etach, Guardlake, Harmon, Limking, Marblemount, Masardis, Sheepscot, Stetson, Teneriffe, and Waiska series. The Colton, Guardlake, Hermon, Masardis, Sheepscot, Stetson, Teneriffe, and Waiska soils have a udic moisture regime. Etach and Marblemount soils have a paralithic contact at 20 to 40 inches. Limking soils are slightly acid to neutral and have 35 to 60 percent granitic rock fragments in the particle-size control section.

GEOGRAPHIC SETTING: Skykomish soils are on glacial outwash terraces at elevations of 400 to 1,800 feet. Slopes range from 0 to 65 percent. The soils formed in glacial outwash with a component of volcanic ash in the upper part. Mean annual precipitation is 50 to 80 inches. Mean January temperature is 33 degrees F, mean July temperature is 61 degrees F, and mean annual temperature is 45 degrees F. The frost-free season is 100 to 140 days. Growing season (28 degrees F) is 130 to 160 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Elwell, Klaus, Olomount, and Winston soils. Elwell soils are coarse-loamy and have dense glacial at a depth of 20 to 40 inches. Klaus soils are mesic and are cemented in the lower part of the spodic horizon. Olomount soils have a lithic contact at a depth of 20 to 40 inches. Winston soils are mesic and are coarse-loamy over sandy or sandy-skeletal.

DRAINAGE AND PERMEABILITY: Somewhat excessively drained; slow to medium runoff; moderately rapid permeability in the solum and very rapid in the 2C horizon.

USE AND VEGETATION: Mostly used for woodland. Native vegetation is western hemlock, Douglas-fir, western redcedar, and red alder, with an understory of salal, Oregon-grape, western swordfern, red huckleberry, western brackenfern, salmonberry, deerfern, and vine maple.

DISTRIBUTION AND EXTENT: Valleys on the west slopes of the Cascade Mountains in northwestern Washington. Series is of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Snohomish County, Washington, 1942.

REMARKS: Classification and remarks only changed 4/94 because of recent amendments to Soil Taxonomy. Partial National Soil Survey Lab data are available on sample number 74-WA-61-1-1-1 through 5. Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the mineral surface to 2 1/2 inches and a cambic horizon from 2 1/2 inches to 19 inches.


National Cooperative Soil Survey
U.S.A.