LOCATION SCAMMAN WAEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Aquic Palexeralfs
TYPICAL PEDON: Scamman silty clay loam, pasture. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 6 inches; dark brown (10YR 3/3) silty clay loam, brown (10YR 5/3( dry; moderate very fine and fine subangular blocky and granular structure; slightly hard, very friable, sticky and slightly plastic; many very fine interstitial pores; neutral (pH 6.6); abrupt smooth boundary. (5 to 7 inches thick)
E--6 to 13 inches; dark yellowish brown (10YR 4/4) silty clay loam, very pale brown (10YR 7/3) dry; common fine prominent grayish brown (2.5Y 5/2) mottles; moderate coarse subangular blocky structure parting to moderate medium and fine subangular blocky; hard, friable, sticky and slightly plastic; common very fine roots; many very fine tubular pores; moderately acid (pH 6.0); clear smooth boundary. (1 to 8 inches thick)
B/E--13 to 23 inches; B part: about 60 percent dark brown (10YR 4/3) silty clay loam, very pale brown (10YR 7/3) dry, as interior of peds; common medium distinct strong brown (7.5YR 5/6) mottles, reddish yellow (7.5YR 6/6) dry, common large faint very pale brown (10YR 8/3) dry mottles; E part: about 40 percent gray (10YR 5/1) silt loam, white (10YR 8/2) dry, on ped surfaces and in pores; 1-5 mm thick; massive, moderate coarse, medium and fine subangular blocky structure; hard, friable, very sticky and slightly plastic; common very fine roots; many very fine and common fine tubular pores; common fine clay films on peds and in pores; moderately acid (pH 6.0); clear smooth boundary. (4 to 14 inches thick)
Btg1--23 to 32 inches; grayish brown (10YR 5/2) silty clay, light gray (10YR 7/2) dry; many large prominent strong brown (7.5YR 5/8) mottles, reddish yellow (7.5YR 6/8) dry; weak coarse prismatic structure parting to strong coarse medium and fine subangular blocky; hard, friable, sticky and plastic; common very fine roots; many very fine tubular pores; many thin and moderately thick clay films on peds and in pores; light gray (10YR 7/2) dry continuous 1-2 mm coatings of albic material on faces of peds; moderately acid (pH 6.0); abrupt smooth boundary. (8 to 15 inches)
Btg2--32 to 60 inches; dark grayish brown (10YR 4/2) silty clay, white (10YR 8/2) dry; many large prominent yellowish red (5YR 4/8) mottles, strong brown (7.5YR 5/8) dry; strong very coarse angular blocky structure parting to strong coarse, medium and fine angular blocky; very hard, firm (compact), sticky and plastic; few very fine roots; continuous thin and moderately thick clay films on faces of peds; slightly acid (pH 6.2).
TYPE LOCATION: Lewis County, Washington, 1,925 feet east, 2,500 feet south of the northwest corner sec. 14, T. 11 N., R. 2 W.
RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 48 to more than 60 inches. Mean annual soil temperature at depth of 20 inches ranges from 47 to 52 degrees F. These soils are usually moist but are dry in all parts of the moisture control section for 45 to 60 consecutive days during the 3-month period following the summer solstice in more than 7 years out of 10. The argillic horizon is silty clay loam, silty clay or clay and averages 40 to 60 percent clay. Rock fragments are 0 to 10 percent by weighted average.
The A or Ap horizon has value of 2 through 4 moist and 4 through 6 dry, and chroma of 2 through 4 moist and dry. It has moderate granular or subangular blocky structure. This horizon is moderately acid to neutral.
The E horizon has hue of 10YR or 2.5Y, value of 4 through 6 moist, 5 through 7 dry, and chroma of 2 through 4 moist and dry. It is silty clay loam or heavy silt loam. It is moderately acid to neutral.
The B portion of the B/E horizon has value of 4 or 5 moist, 5 through 7 dry, and chroma of 3 or 4 moist or dry. It is silty clay loam or silty clay and occupies 55 to 65 percent of the horizon. The E portion has value of 4 or 5 moist, 7 or 8 dry, and chroma of 1 or 2 moist or dry and occupies 30 to 45 percent of the B/E horizon. It is moderately acid or slightly acid.
The Btg horizon has hue of 10YR, 2.5Y or 5Y, value of 4 or 5 moist, 6 through 8 dry, and chroma of 1 through 3 moist, 2 or 3 dry. It has many to continuous, thin to thick clay films on faces of peds and in pores. It is strongly acid to slightly acid. Rock fragments range from 5 to 15 percent.
COMPETING SERIES: These are the Bow, Coveland, Coweeman, and Hardscrabble series. Bow soils have a mantle 9 to 17 inches thick influenced by volcanic ash. Coveland soils have a very gravelly E horizon. Coweeman soils are strongly acid to moderately acid in the A horizon and lack a B/E horizon. Hardscrabble soils are very strongly acid to the 2Bt horizon and lack a B/E horizon.
GEOGRAPHIC SETTING: These soils occur on high terraces and foothills at elevations of 150 to 2,000 feet. Slopes range from 0 to 70 percent. They formed in mixed material weathered from glacial and sedimentary sources. These soils occur in a climate with 40 to 70 inches annual precipitation occurring mostly as rain in the winter. Mean January temperature is 38 degrees F, mean July temperature is 65 degrees F, and mean annual temperature is 52 degrees F. Frost-free season is 150 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cinebar, Klaber, Prather, Lacamas, Melbourne, and Salkum soils. Cinebar, Melbourne, and Salkum soils lack chroma of 2 or less and are well drained. Klaber and Lacamas soils have an aquic moisture regime. Prather soils are kaolinitic.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow to medium runoff; moderate permeability to the argillic horizon and slow through it. A perched water table is as high as .5 to 1.5 feet below the soil surface for periods during November through March.
USE AND VEGETATION: Used for woodland and cropland. Winter wheat, corn silage, oats, hay and pasture are common crops. Native vegetation is Douglas-fir, western hemlock, western redcedar, red alder, big leaf maple, bittercherry, and Oregon ash, with an understory of salal, vine maple, western swordfern, Oregon-grape, western brackenfern, red huckleberry, trailing blackberry, salmonberry, creambush oceanspray, Oregon oxalis, rose, red huckleberry, and Cascara buckthorn.
DISTRIBUTION AND EXTENT: Southwestern Washington. Series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Lewis County, Washington, 1941.
REMARKS: Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the surface to 6 inches, an albic horizon from 6 to 13 inches that tongues into an argillic horizon from 13 to 23 inches, and an argillic horizon from 13 to 60 inches.