LOCATION FIDALGO WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, mesic Vitrandic Dystroxerepts
TYPICAL PEDON: Fidalgo gravelly loam-forested. (Colors are for moist soil unless otherwise noted. All textures are apparent field textures.)
Oi--0 to 1 inch; needles, leaves and twigs.
A--1 to 4 inches; very dark brown (7.5YR 2/2) gravelly loam, dark brown (7.5YR 3/2) dry; weak very fine granular structure; soft, very friable, slightly sticky AND nonplastic and weakly smeary; common very fine, fine, medium and coarse roots; 25 percent rounded and angular pebbles and 5 percent cobbles; neutral (pH 7.0); clear smooth boundary. (0 to 4 inches thick)
Bw1--4 to 13 inches; dark brown (7.5YR 4/2) very gravelly fine sandy loam, brown (7.5YR 5/4) dry; moderate medium subangular blocky structure; soft, very friable, nonsticky AND nonplastic, and very weakly smeary; common very fine, fine, medium and coarse roots; 35 percent rounded and angular pebbles; NaF ph 10.5; neutral (pH 6.6); clear irregular boundary. (7 to 12 inches thick)
Bw2--13 to 19 inches; dark brown (7.5YR 4/4) very gravelly fine sandy loam, brown (7.5YR 5/4) dry; weak coarse subangular blocky structure; soft, very friable, nonsticky AND nonplastic and very weakly smeary; common very fine, fine, medium and coarse roots; 45 percent angular and rounded pebbles; NaF pH 10.1; neutral (pH 6.8); clear wavy boundary. (5 to 10 inches thick)
BC--19 to 26 inches; dark brown (7.5YR 3/2) very gravelly sandy loam, dark brown (7.5YR 4/4) dry; massive; soft, very friable, nonsticky and nonplastic; common very fine, fine, medium and coarse roots; 50 percent angular and rounded pebbles; NaF pH 9.2; neutral (pH 6.8); clear wavy boundary. (6 to 10 inches thick)
C--26 to 30 inches; very dark brown (10YR 2/2) extremely gravelly loamy sand, dark brown (7.5YR 4/2) dry; single grain, loose; common fine, medium and coarse roots; 65 percent angular and rounded pebbles and 10 percent angular cobbles; neutral (pH 6.6); abrupt wavy boundary. (0 to 6 inches thick)
2R--30 inches; hard argillite.
TYPE LOCATION: Fidalgo Island, Skagit County, Washington; 1,000 feet east and 1,000 feet south of the northwest corner sec. 1, T. 34 N., R. 1 E.
RANGE IN CHARACTERISTICS: Depth to a lithic contact is 20 to 40 inches. Coarse fragments in the particle-size control section average 35 to 80 percent. These soils are usually moist, but are dry in the moisture control section for 60 to 75 consecutive days following summer solstice. The mean annual soil temperature is estimated to range from 48 to 52 degrees F.
The A horizon has hue of 5YR, 7.5YR or 10YR, value of 2 or 3 moist. 3 through 6 dry, and chroma of 2 through 4. Reaction is slightly acid or neutral.
The Bw horizon has hue of 5YR, 7.5YR or 10YR, value of 4 or 5 moist, 4 through 6 dry; and chroma of 2 through 6. It is very gravelly loam, very gravelly fine sandy loam, or very gravelly sandy loam. Reaction is slightly acid or neutral.
The BC horizon has hue of 7.5YR or 10YR, value of 3 through 5 moist or dry, and chroma of 2 through 4. It is very gravelly sandy loam or very gravelly fine sandy loam.
The C horizon has hue of 7.5YR through 2.5Y, value of 2 through 4 moist, 3 through 6 dry, and chroma of 2 through 4. It is extremely gravelly loamy sand or very gravelly sandy loam. Reaction is slightly acid or neutral.
COMPETING SERIES: These are the Whistle and Yedlick series. Whistle soils lack a lithic contact within depths less than 40 inches. Yedlick soils are more than 40 inches deep.
GEOGRAPHIC SETTING: Fidalgo soils are on hillslopes at elevations of 20 to 1,300 feet. They formed in colluvium, glacial till and residuum from serpentine, argillite, and basalt with an admixture of volcanic ash and loess in the upper part. Slopes range from 3 to 90 percent. Average annual precipitation is 18 to 30 inches. Average estimated January temperature is about 36 degrees F, average estimated July temperature is about 64 degrees F, and the mean annual temperature is about 50 degrees F. Frost-free season is 160 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Swinomish and the competing Whistle soils. Swinomish soils have a paralithic contact with dense glacial till at a depth of 20 to 40 inches.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium runoff; moderate permeability.
USE AND VEGETATION: Woodland is the principal use. Native vegetation is Douglas-fir and Pacific madrone, with an understory of Oregon-grape, trailing blackberry, salal, creambush oceanspray, longtube twinflower, ninebark, broadleaf starflower, sticky currant, and Indian plum.
DISTRIBUTION AND EXTENT: Western Skagit County, Washington. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Skagit County, Washington, 1953.
REMARKS: Classification only changed 4/94 because of recent amendments to Soil Taxonomy. Estimate glass more than 5 percent and acid-oxalate extract more than 0.4 percent from 0 to 18 inches. Diagnostic horizons and features recognized in this pedon are an ochric epipedon, a cambic horizon from 4 to 26 inches, a lithic contact at 30 inches, and a particle-size control section from 11 to 30 inches that averages 52 percent rock fragment.