LOCATION GOBLE OREstablished Series
TAXONOMIC CLASS: Fine-silty, isotic, mesic Andic Fragiudepts
TYPICAL PEDON: Goble silt loam, woodland. (Colors are for moist soil unless otherwise noted.)
Oi--0 to 1 inch; needles, twigs, moss, leaves, etc.
A1--1 to 8 inches; very dark grayish brown (10YR 3/2) silt loam, brown (10YR 5/3) dry; strong fine granular structure; soft, friable, slightly sticky and slightly plastic; many fine roots; many fine and very fine pores; many fine concretions; moderately acid (pH 5.6); abrupt smooth boundary. (6 to 9 inches thick)
A2--8 to 15 inches; dark brown (10YR 3/3) silt loam, yellowish brown (10YR 5/4) dry; strong fine granular structure; soft, friable, slightly sticky and slightly plastic; many fine roots; many very fine pores; few fine concretions; strongly acid (pH 5.4); clear smooth boundary. (6 to 9 inches thick)
Bw1--15 to 27 inches; dark brown (7.5YR 3/4) silt loam, yellowish brown (10YR 5/4) dry; moderate fine subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common fine and few medium roots; many very fine pores; strongly acid (pH 5.4); clear smooth boundary. (9 to 13 inches thick)
Bw1--27 to 38 inches; dark brown (10YR 4/3) silty clay loam, light yellowish brown (10YR 6/4) dry; moderate fine subangular blocky structure; slightly hard, firm, moderately sticky and moderately plastic; few fine roots; common very fine pores; strongly acid (pH 5.2); abrupt smooth boundary. (10 to 12 inches thick)
2Btx--38 to 51 inches; dark yellowish brown (10YR 4/4) silty clay loam, light yellowish brown (10YR 6/4) dry; many fine and medium distinct dark brown (7.5YR 3/2), strong brown (7.5YR 5/6) and light gray (10YR 7/1) redox features and light gray (10YR 7/1) tongues in fracture planes; numerous fine and medium black stains; weak very coarse prismatic and medium blocky and some subangular blocky structure; hard, brittle, very firm, moderately sticky and moderately plastic; common very fine pores; common faint clay films in fractures and on prism sides; very strongly acid (pH 5.0).
TYPE LOCATION: Multnomah County, Oregon; about 30 feet west of Skyline Blvd.; NE1/4 NW1/4 NE1/4 section 3, T.2N., R.2W., W.M.
RANGE IN CHARACTERISTICS: The soils have a udic moisture regime but have a dry period of less than 45 days during the summer. The mean annual soil temperature ranges from 47 degrees to 55 degrees F. The depth to the fragipan ranges from 30 to 45 inches. The soil is more than 60 inches deep to bedrock. The umbric epipedon is 10 to 20 inches thick.
The A horizon has value of 4 or 5 dry, and chroma of 2 or 3 moist and 2 through 4 dry.
The Bw horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist and 5 or 6 dry, and chroma of 3 or 4. It is typically silty clay loam, but includes silt loam in the upper part. None to few faint mottles with chroma of 3 or 4 in hue of 5YR are near the boundary with the fragipan in some pedons. This horizon has a smeary feel when moist.
The Btx horizon (fragipan) has matrix colors similar to the horizon above it, but has distinct and prominent mottles with chroma of 2. It is hard, very firm, and has a brittle feel. Clay films on prism faces and fractures are common or continuous and thin. The fragipan is normally more than one foot thick and overlies old alluvium or loess, and residual material of mixed origin.
COMPETING SERIES: These are the Cascade, Dollar, Kinton and Powell series. Cascade soils have fragipans at depths of less than 30 inches and are mottled at depths of 20 to 30 inches. Dollar soils are fine-loamy. Kinton and Powell soils have ochric epipedons and xeric moisture regimes. Also, Powell soils are mottled at depths of 20 to 30 inches.
GEOGRAPHIC SETTING: The Goble soils are on smooth or rolling hills with convex, long slopes and ridgetops on all exposures at elevations of 200 to 1,800 feet. The soils formed in loess over mixed old alluvium or slope wash. The soils formed under a cool moist winter and a warm dry summer climate. Average July temperature is 64 degrees F., average January temperature is 34 degrees F., average annual temperature is 49 degrees F. Average annual precipitation is 60 to 75 inches. Frost-free period is 180 to 190 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Delena, Olyic and Melby soils and the competing Cascade soils. Delena soils are poorly drained, and have chroma of 2 or less and mottles throughout the B horizon and the fragipan. Olyic and Melby soils lack fragipans.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow to medium surface runoff; moderate permeability above the fragipan and slow in the fragipan.
USE AND VEGETATION: Small grains and seed crops, hay, pasture, and woodland. Small areas are used for berries. Native vegetation consists of Douglas-fir, western redcedar, big leaf maple, alder, vine maple, salal, swordfern.
DISTRIBUTION AND EXTENT: Northwestern Oregon. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Washington County, Oregon, 1975.