LOCATION SNOQUALMIE              WA

Established Series
Rev. JAF-RJE
04/2012

SNOQUALMIE SERIES

The Snoqualmie series consists of very deep, somewhat excessively drained soils formed in alluvium on low river terraces. Slopes are 0 to 8 percent. The mean annual precipitation is about 65 inches and the mean annual air temperature is about 48 degrees F.

TAXONOMIC CLASS: Sandy-skeletal, mixed, mesic Dystric Xerorthents

TYPICAL PEDON: Snoqualmie loamy fine sand on a nearly level river terrace under coniferous forest at 1,400 feet elevation. (Colors are for moist soil unless otherwise noted.)

Oi--0 to 1 inch; slightly decomposed needles, leaves, and twigs; abrupt smooth boundary. (0 to 1 inch thick)

A--1 to 9 inches; very dark grayish brown (10YR 3/2) loamy fine sand, dark grayish brown (10YR 4/2) dry; single grain; loose; many very fine, fine, and medium, and common coarse roots; moderately acid (pH 6.0); abrupt smooth boundary. (6 to 20 inches thick)

C1--9 to 37 inches; very dark gray (10YR 3/1) extremely gravelly coarse sand, dark gray (N 4/0) dry; single grain; loose; common fine, medium, and coarse, and few very fine roots; 50 percent gravel, 20 percent cobbles; moderately acid (pH 6.0); abrupt smooth boundary. (8 to 28 inches thick)

C2--37 to 61 inches; very dark gray (10YR 3/1) extremely cobbly coarse sand, dark gray (N 4/0) dry; single grain; loose; 40 percent gravel, 25 percent cobbles; slightly acid (pH 6.2); clear smooth boundary.

TYPE LOCATION: Snoqualmie Pass Area, King County, Washington; about 10 miles east of Enumclaw of U.S. Highway 410; 1,800 feet west and 1,250 feet south of the northeast corner, sec. 3, T. 19 N., R. 8 E.

RANGE IN CHARACTERISTICS: These soils are usually moist, but are dry in the moisture control section for 45 to 60 consecutive days following summer solstice. The mean annual soil temperature is 47 to 51 degrees F. The particle-size control section averages 40 to 785 percent rounded rock fragments. The upper 40 inches of the pedon has hue of 10YR or 7.5YR, value of 2 to 4 moist, 4 or 5 dry, and chroma of 1 to 3 moist, 0 to 2 dry. Reaction is moderately acid to neutral throughout.

COMPETING SERIES: These are the Grove, Neilton, Netrac, and Wiseman series. Grove and Neilton soils have Bs horizons. Netrac soils have a volcanic ash surface layer that is 7 to 14 inches thick. Wiseman soils are 40 to 80 percent phyllite channers in the particle-size control section.

GEOGRAPHIC SETTING: Snoqualmie soils formed in alluvium on low river terraces. Slopes are 0 to 8 percent. Snoqualmie soils occur at elevations of 40 to 1,700 feet. The mean annual precipitation is 50 to 90 inches. The mean January temperature is about 43 degrees F; the mean July temperature is about 62 degrees F; and the mean annual temperature is 46 to 50 degrees F. The frost-free season is 130 to 180 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Greenwater, Klaus, Lemolo, and Pilchuck soils. Greenwater and Pilchuck soils have less than 35 percent rock fragments in the particle-size control section. Lemolo soils are loamy-skeletal and have an aquic moisture regime. Klaus soils have a spodic horizon.

DRAINAGE AND PERMEABILITY: Somewhat excessively drained; very slow runoff; very rapid permeability. The soils are subject to common, brief flooding during November through April. The water table is as high as 3 to 5 feet at times from November through April.

USE AND VEGETATION: Timber production is the principal use. Native vegetation is Douglas-fir, western hemlock, western redcedar, black cottonwood and red alder with an understory of vine maple, western swordfern, red huckleberry, Oregon-grape, longtube twinflower, trailing blackberry, thimbleberry, trillium, bunchberry dogwood, salmonberry, deer fern, and deerfoot vanillaleaf.

DISTRIBUTION AND EXTENT: Valleys of the west slopes of the Cascade Mountains in Washington; MLRA 2 and 3. The series is of small extent.

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

SERIES ESTABLISHED: King County, Washington, 1943.

REMARKS: Diagnostic horizons and features recognized in this pedon are: an ochric epipedon and a particle-size control section from 11 to 41 inches that is sandy throughout and averages 69 percent rock fragments.

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National Cooperative Soil Survey
U.S.A.