LOCATION TROMP WAEstablished Series
TAXONOMIC CLASS: Sandy, mixed, mesic Aquic Haplorthods
TYPICAL PEDON: Tromp loam - on a 1 percent northeast facing slope in pasture at 70 feet elevation. (Colors are for moist soil unless otherwise noted. All textures are apparent field textures.)
Ap--0 to 11 inches; dark brown (10YR 3/3) loam, light yellowish brown (10YR 6/4) dry; weak medium subangular blocky parting to weak fine granular structure; soft, very friable, nonsticky, nonplastic, weakly smeary; many very fine and fine roots; many very fine irregular pores; NaF pH 12.0; moderately acid (pH 5.6); abrupt smooth boundary. (5 to 11 inches thick)
BS1--11 to 15 inches; dark brown (7.5YR 4/4) loam, brownish yellow (10YR 6/6) dry; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic, weakly smeary; common very fine and fine roots; many very fine irregular pores; NaF pH 12.0; strongly acid (pH 5.2); clear smooth boundary. (4 to 14 inches thick)
BS2--15 to 20 inches; strong brown (7.5YR 4/6) loam, reddish yellow (7.5YR 6/6) dry; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic, weakly smeary; common very fine and fine roots; many very fine irregular pores; NaF pH 12.0; strongly acid (pH 5.4); abrupt smooth boundary. (4 to 18 inches thick)
BCs--20 to 26 inches; dark yellowish brown (10YR 4/4) sandy loam, light yellowish brown (10YR 6/4) dry; many fine prominent strong brown (7.5YR 5/8) mottles, reddish yellow (7.5YR 6/8) dry; massive; slightly hard, friable, nonsticky, nonplastic; common very fine and fine roots; common fine irregular pores; NaF pH 11.5; moderately acid (pH 5.6); abrupt smooth boundary. (5 to 18 inches thick)
2CBs--26 to 46 inches; olive brown (2.5Y 4/4) weakly cemented medium sand, pale yellow (2.5Y 7/4) dry; common medium prominent yellowish brown (10YR 5/6) and dark grayish brown (2.5Y 4/2) mottles, brownish yellow (10YR 6/6) and light gray (2.5Y 7/2) dry; massive; slightly hard, friable, nonsticky, nonplastic; many fine irregular pores; NaF pH 12.0; moderately acid (pH 5.8); clear irregular boundary. (2 to 22 inches thick)
2C--46 to 60 inches; dark grayish brown (2.5Y 4/2) and grayish brown (2.5Y 5/2) medium sand, light brownish gray (2.5Y 6/2) and light gray (2.5Y 7/2) dry; common medium prominent yellowish brown (10YR 5/6) mottles, brownish yellow (10YR 6/6) dry; single grain; loose; NaF pH 11.0; moderately acid (pH 5.8).
TYPE LOCATION: Whatcom County, Washington; about 2 miles north of Ferndale; 2,300 feet south and 1,800 feet east of the northwest corner of sec. 8, T. 39 N., R. 2 E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature is 50 to 54 degrees F. Thickness of the influence of volcanic ash is 14 to 30 inches. The particle-size control section has by weighted average is loamy sand with 0 to 5 percent pebbles.
The A horizon has hue of 7.5YR or 10YR, value of 3 or 4 moist, 4 through 6 dry, and chroma of 2 through 4 moist and dry. Reaction is strongly acid or moderately acid.
The Bs horizon has hue of 7.5YR or 10YR, value of 3 or 4 moist, 4 through 6 dry, and chroma of 3 through 6 moist and dry. Rock fragments range from 0 to 5 percent. It is loam, silt loam, or fine sandy loam. Reaction is strongly acid or moderately acid.
The BCs and 2CBs horizons have hue of 10YR or 2.5Y, value of 3 through 5 moist, 4 through 7 dry, and chroma of 2 through 4 moist and dry. Rock fragments range from 0 to 5 percent. The 2CB horizon has weak cementation expressed either as a massive horizon with slightly hard to hard dry consistence or as 2 to 15 percent ortstein fragments l/4 to 2 inches in diameter having consistence of slightly hard to hard when dry. The BCs horizon is sandy loam or fine sandy loam. The 2CBs horizon is loamy sand or sand.
The 2C horizon has hue of 10YR through 5Y, value of 3 through 5 moist, 4 through 7 dry, and chroma of 2 through 4 moist and dry. Rock fragments range from 0 to 10 percent. It is sand or loamy sand. Reaction is moderately acid or slightly acid.
COMPETING SERIES: This is the Yaquina series and the similar Clipper, Hale, and Laxton series. Clipper soils are coarse-loamy. Yaquina soils are sandy throughout. Hale and Laxton soils are coarse-loamy over sandy or sandy-skeletal.
GEOGRAPHIC SETTING: Tromp soils are on outwash terraces and outwash plains at elevations of 50 to 300 feet. Slopes are 0 to 2 percent. The soils formed in volcanic ash, loess, and sandy glacial outwash. Tromp soils are in a marine climate with warm, dry summers and cool, moist winters. Snow cover is intermittent. Average annual precipitation is 40 to 55 inches, which falls mostly between October and May. Each of the summer months has at least one inch of rainfall. Mean January temperature is 36 degrees F; mean July temperature is 62 degrees F. The mean annual temperature is 50 degrees F. The frost-free season is 150 to 190 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Hale and Laxton soils, and the Edmonds, Lynden, Pangborn, and Woodlyn soils. Edmonds and Woodlyn soils have an aquic moisture regime. Lynden soils lack mottles with a chroma of 2 or less in the upper 75 cm. Pangborn soils are Histosols.
DRAINAGE AND PERMEABILITY: Moderately well drained; very slow runoff; permeability is moderate in the upper part of the solum, and rapid in the substratum. An apparent water table is as high as 1.5 to 2.5 feet at times from November through April.
USE AND VEGETATION: Used mainly for cropland. Berry crops, hay and pasture are common crops. Some is used for timber production, and homesites. Native vegetation is Douglas-fir, western hemlock, western redcedar, and red alder with an understory of western swordfern, salal, red huckleberry, vine maple, western brackenfern, and Oregon-grape.
DISTRIBUTION AND EXTENT: Northwestern Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Whatcom County, Washington, l945.
REMARKS: This draft reflects a change in classification from medial over sandy or sandy-skeletal, mixed, mesic Aquic Dystric Xerochrepts to sandy, mixed, mesic Aquic Haplorthods. Characterization data are available on these soils. Laboratory number S81WA-073-4. Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the surface to 11 inches, and a spodic horizon from 11 to 26 inches. The spodic horizon does not meet chemical criteria for a spodic horizon but does have micro morphology, i.e. cracked coatings and silt-sized and larger pellets.