LOCATION ILLABOT WAEstablished Series
TAXONOMIC CLASS: Medial-skeletal, amorphic, frigid Vitric Hapludands
TYPICAL PEDON: Illabot very gravelly loam - on a 17 percent convex south-facing slope under a forest canopy. (Colors are for moist soil unless otherwise stated. All textures are apparent field textures.)
01--3 to 1 inch; accumulation of needles, twigs, and roots.
02--1 inch to 0; partially decomposed forest litter.
A1-0 to 3 inches; brown (10YR 4/3) very gravelly loam, very pale brown (10YR 7/3) dry; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic, weakly smeary; common fine roots; common very fine irregular pores; 45 percent rounded pebbles, 5 percent cobbles; NaF pH 10.0; moderately acid (pH 6.0); abrupt wavy boundary. (0 to 7 inches thick)
B21--3 to 9 inches; yellowish brown (10YR 5/4) very gravelly loam, light yellowish brown (10YR 6/4) dry; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic, weakly smeary; common fine roots; common fine irregular pores; 45 percent rounded pebbles, 5 percent cobbles; NaF pH 10.0 moderately acid (pH 6.0); abrupt wavy boundary. (5 to 17 inches thick)
B22--9 to 30 inches; light olive brown (2.5Y 5/4) very gravelly loam, pale yellow (2.5Y 7/4) dry; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common fine irregular pores; 45 percent rounded pebbles, 5 percent cobbles; NaF pH 10.0; moderately acid (pH 6.0); abrupt wavy boundary. (6 to 21 inches thick)
2Cd--30 to 60 inches; olive brown (2.5Y 4/4) dense glacial till that breaks to very gravelly sandy loam, pale olive (5Y 6/3) dry; massive; very hard, very firm, slightly sticky and slightly plastic; few very fine tubular pores; 45 percent rounded pebbles, 5 percent cobbles; moderately acid (pH 5.6)
TYPE LOCATION: Skagit County, Washington; about 1 mile east of Concrete, Washington; 205 feet north and 1,850 feet east of the southwest corner, sec. 1, T. 35 N., R. 8 E.
RANGE IN CHARACTERISTICS: The thickness of the solum and depth to a paralithic contact with dense glacial till is 20 to 40 inches. These soils are usually moist but are dry for 45 to 60 consecutive days following summer solstice. Mean annual soil temperature is estimated to range from 45 to 47 degrees F. Depth of influence of volcanic ash ranges from 8 to 14 inches. Reaction is strongly acid or moderately throughout.
The A horizon has hue of 7.5YR or 10YR, value of 4 or 5 moist, 6 through 8 dry, and chroma of 3 or 4 moist and dry.
The B horizon has hue of 7.5YR, 10YR, or 2.5Y, value of 4 or 5 moist, 5 through 7 dry, and chroma of 4 or 5 moist and dry. It is loam or sandy loam with 6 to 15 percent clay. Rock content averages from 40 to 60 percent.
The 2Cd horizon has hue of 2.5Y or 5Y, value of 4 or 5 moist, 6 or 7 dry, and chroma of 3 or 4 moist and dry. It is dense glacial till that breaks to very gravelly sandy loam or very gravelly loam. Clay content is 5 to 12 percent. Rock fragments average from 40 to 60 percent.
COMPETING SERIES: These are the Belzar, Hartill, Inkler, Newbell, Rinker, Sugarbowl, Talls, and Yedlick series. Belsar and Rinker soils have a lithic contact within the control section. Hartill soils are neutral or slightly acid and are dry for more than 60 consecutive days. Inkler, Newbell, Oakes, Sugarbowl, Talls, and Yedlick soils lack a paralithic contact within depths of 40 inches.
GEOGRAPHIC SETTING: Illabot soils are on glacially modified mountain sides. Slopes range from 3 to 65 percent. Elevation is 1,000 to 2,200 feet. These soils formed in glacial till with a surface mixture of volcanic ash. The average annual precipitation is 65 to 80 inches, and the mean annual temperature is 43 to 44 degrees F. Average January temperature is about 33 degrees F., and average July temperature is about 61 degrees F. The frost-free season is 120 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Barneston, Kindy, and Saar soils. Barneston soils are sandy-skeletal and mesic. Kindy and Saar soils have a spodic horizon and are cryic.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow to rapid runoff; moderate permeability.
USE AND VEGETATION: Used for woodland. Native vegetation consists of western hemlock, Douglas-fir, western redcedar, Oregon-grape, salal, western swordfern, western brackenfern, longtube twinflower, red huckleberry, and vine maple.
DISTRIBUTION AND EXTENT: Northwestern Washington. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Skagit County, Washington, 1981.
REMARKS: Classification changed 4/94 because of recent amendments to Soil Taxonomy, and in addition the nomenclature of the Cr was changed to Cd.