LOCATION GREENWATER WAEstablished Series
TAXONOMIC CLASS: Mixed, mesic Dystric Xeropsamments
TYPICAL PEDON: Greenwater loamy sand - grass. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 9 inches; very dark brown (10YR 2/2) loamy sand, dark grayish brown (10YR 4/2) dry; weak very fine granular structure; soft, very friable; nonsticky and nonplastic; many very fine roots; about 7 percent fine pumice; moderately acid (pH 5.8); clear smooth boundary. (5 to 10 inches thick)
Bw--9 to 19 inches; dark yellowish brown (10YR 3/4) loamy sand, yellowish brown (10YR 5/4) dry; massive; soft, friable; nonsticky and nonplastic; many very fine roots; about 10 percent fine pumice; moderately acid (pH 5.8); clear smooth boundary. (0 to 12 inches thick)
C1--19 to 26 inches; very dark grayish brown (10YR 3/2) sand, gray (10YR 5/1) dry; massive; slightly hard, firm; nonsticky and nonplastic; few very fine roots; compact (somewhat water stable) coarse stratified layers; 8 percent fine pumice; moderately acid (pH 6.0); gradual smooth boundary. (5 to 8 inches thick)
C2--26 to 60 inches; very dark gray (10YR 3/1) sand, gray (10YR 5/1) dry; single grain; loose; nonsticky and nonplastic; few very fine roots; about 12 percent fine pumice; moderately acid (pH 6.0).
TYPE LOCATION: Snoqualmie Pass Area, Pierce County, Washington; 500 feet west and 3,000 feet north of the southeast corner, sec. 2, T. 19 N., R. 6 E.
RANGE IN CHARACTERISTICS: The average annual soil temperature is 48 to 51 degrees F. These soils are usually moist, but are dry in all parts for 60 to 75 consecutive days. The control section contains less than 15 percent rock fragments and 5 to 25 percent volcanic ash, cinders, and pumice.
The A horizon has hue of 10YR or 2.5Y, value of 2 to 5 moist, 3 to 7 dry, and chroma of 2 or 3 moist and 2 to 6 dry.
The Bw horizon has hue of 2.5Y to 7.5YR, value of 3 to 5 moist, 4 to 7 dry, and chroma of 2 to 4 moist and dry. Below 10 inches it is fine sand, loamy sand or sand and has weak blocky structure or is massive or single grain. Reaction is strongly acid to neutral.
The C horizon has hue of 10YR through 5Y, value of 3 to 6 moist, 4 to 8 dry, and chroma of 1 to 4. The upper part above 40 inches has 0 to 35 percent rock fragments. At depths below 40 inches the C horizon is sand or coarse sand modified by 35 to 75 percent rock fragments or is stratified with thin layers of sandy loam and silt loam in some pedons. Reaction is moderately acid to neutral.
COMPETING SERIES: These are the Birdsview, Indianola, Keystone, and Pilchuck series. These soils lack pumice in the particle-size control section.
GEOGRAPHIC SETTING: The Greenwater soils are on low terraces at elevations from 100 to 1,800 feet. Slopes are 0 to 45 percent slopes. They formed in mixed alluvium derived mainly from andesite and pumice. They are in a mild maritime humid climate. Average annual precipitation is 40 to 80 inches, average January temperature is 38 degrees F, average July temperature is 61 degrees F, and average annual temperature is about 49 degrees F. The frost-free season ranges from 130 to 170 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Buckley, Ledow, National, Siler, Schooley, and Snoqualmie soils and the competing Pilchuck soils. Buckley soils are poorly drained and have more than 18 percent clay in the control section. Ledow soils have an irregular decrease in organic carbon and layers finer than fine sand in the control section. National soils are cindery over medial. Siler soils are ashy over medial. Schooley soils are ashy over loamy and have an aquic moisture regime. Snoqualmie soils are sandy-skeletal.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; slow runoff; rapid permeability. Flooding is none or rare.
USE AND VEGETATION: Greenwater soils are used for woodland, pasture, and homesites. Native vegetation is mainly Douglas-fir, western hemlock, red alder, western redcedar, and bigleaf maple with an understory of salal, western swordfern, creambush oceanspray, trailing blackberry, rose, western brackenfern, red huckleberry, and Oregon-grape.
DISTRIBUTION AND EXTENT: Valleys on the west slopes of the Cascade Mountains in western Washington. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: King County, Washington, 1939.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
a. ochric epipedon from the mineral surface to 9 inches and a particle-size control section from 10 to 40 inches that is sandy throughout.