LOCATION EARLMONT WAEstablished Series
TAXONOMIC CLASS: Fine-silty, siliceous, superactive, acid, mesic Fluvaquentic Endoaquepts
TYPICAL PEDON: Earlmont silt loam - cultivated. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 9 inches; dark grayish brown (10YR 4/2) silt loam (diatomaceous earth), white (10YR 8/1) dry; moderate coarse and very coarse granular structure; slightly hard, friable, nonsticky, nonplastic; many roots; strongly acid (pH 5.4); abrupt smooth boundary. (7 to 11 inches thick)
Bw1--9 to 25 inches; grayish brown (10YR 5/2) silt loam (diatomaceous earth), white (10YR 8/1) dry; common fine prominent brown (7.5YR 4/4) and many large distinct yellowish brown (10YR 5/6 and 5/8) redox concentrations, brownish yellow (10YR 6/6) and yellow (10YR 7/6) dry; moderate very coarse prismatic structure; hard, firm, slightly sticky, slightly plastic; common roots; very strongly acid (pH 4.8); gradual smooth boundary. (13 to 16 inches thick)
Bw2--25 to 41 inches; light brownish gray (2.5Y 6/2) silty clay loam (diatomaceous earth), white (N 8/) dry; common fine prominent yellowish red (5YR 5/8) redox concentrations in root casts, yellow (10YR 7/6 and 8/6) dry; moderate very coarse prismatic structure; hard, firm, moderately sticky and moderately plastic; common roots; very strongly acid (pH 4.8); clear smooth boundary. (16 to 20 inches thick)
Bw3--41 to 44 inches; brown (10YR 5/3) and light brownish gray (10YR 6/2) silt loam (diatomaceous earth), white (N 8/) dry; common fine prominent yellowish brown (10YR 5/6) redox concentrations, light yellowish brown (10YR 6/4) and brownish yellow (10YR 6/6) dry; moderate very coarse prismatic structure; hard, firm, slightly sticky, slightly plastic; common roots; very strongly acid (pH 4.8); abrupt smooth boundary. (2 to 4 inches thick)
2C1--44 to 46 inches; very pale brown (10YR 7/3) very fine sandy loam and silt loam (volcanic ash), white (10YR 8/1) dry; common fine prominent strong brown (7.5YR 5/8) redox concentrations, pale brown (10YR 6/3) dry; massive; hard, firm, nonsticky, nonplastic; common roots; very strongly acid (pH 4.6); abrupt smooth boundary. (0 to 3 inches thick)
3C2--46 to 48 inches; black (10YR 2/1) and very dark brown (10YR 2/2) muck, dark grayish brown (10YR 4/2) dry; 5 percent white (10YR 8/1) streaks dry; massive; hard, firm, slightly sticky, slightly plastic; few roots; very strongly acid (pH 4.8); abrupt smooth boundary. (0 to 3 inches thick)
4C3--48 to 60 inches; very dark brown (10YR 2/2) and light gray (10YR 7/2) laminations of diatomite and muck, white (N 8/) and grayish brown (10YR 5/2) dry; common medium prominent yellowish brown (10YR 5/6 and 5/8) redox concentrations in the diatomite, very pale brown (10YR 8/4) dry; weakly laminar; hard, firm, slightly sticky, slightly plastic; few roots; very strongly acid (pH 4.8).
TYPE LOCATION: King County, Washington; 930 feet west and 250 feet north of the east 1/4 corner of section 27, T. 26 N., R. 5 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 48 to 54 degrees F. The control section contains less than 15 percent particles coarser than very fine sand, 22 to 32 percent clay, and less than 5 percent coarse fragments. The soil is strongly acid at the surface and very strongly acid in the subsoil.
The Ap horizon has moderately coarse and very coarse granular structure.
The B horizon is grayish brown (10YR 5/2), brown (10YR 5/3), or light brownish gray (10YR 6/2 and 2.5Y 6/2), with fine and medium, distinct and prominent redox concentrations. It is silt loam or silty clay loam. It has moderate to strong very coarse prismatic structure.
The C horizon has layers of volcanic ash, peat, muck, and diatomite. Some pedons contain gravel lenses below a depth of 4 feet.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: These soils are on nearly level flood plains at elevations of about 40 feet. They formed in diatomaceous earth with some lenses of volcanic ash and muck below 40 inches. Average January temperature of 38 degrees F., average July temperature is 64 degrees F., and mean annual temperature is 50 degrees F. The frost-free season is about 200 days. The mean annual precipitation is 45 to 50 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Snohomish and Tukwila soils. Snohomish soils have peaty muck within the control section. Tukwila soils are deep organic soils.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Permeability is moderate. Runoff is slow.
USE AND VEGETATION: Mostly row crops and seeded grass pasture.
DISTRIBUTION AND EXTENT: Northwestern Washington. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: King County, Washington, 1971.
REMARKS: Diagnostic horizons and other features:
Ochric epipedon
Cambic horizon - 9 to 44 inches