LOCATION THREEMILE WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Andic Haploxerepts
TYPICAL PEDON: Threemile ashy silt loam - woodland. (Colors are for dry soil unless otherwise stated.)
Oe--0 to 1 inch; very dark grayish brown (10YR 3/2) moist, partially decomposed organic litter composed of leaves, needles, bark, twigs, and cones; slightly acid (pH 6.2); abrupt smooth boundary. (1 to 2 inches thick)
Bw1--1 to 5 inches; yellowish brown (10YR 5/4) ashy silt loam, dark brown (7.5YR 4/4) moist; weak, fine granular structure; soft, very friable, slightly sticky and slightly plastic; weakly smeary; many very fine, fine, and common medium roots; many very fine vesicular pores; 5 percent pebbles; neutral (pH 7.2); clear wavy boundary. (2 to 5 inches thick)
Bw2--5 to 11 inches; yellowish brown (10YR 5/4) ashy loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; weakly smeary; many very fine, fine, and common medium roots; many very fine vesicular pores; 10 percent pebbles; neutral (pH 6.8); clear wavy boundary. (4 to 8 inches thick)
2BC--11 to 16 inches; brown (10YR 5/3) gravelly loam, dark brown (10YR 4/3) moist; moderate fine subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; common very fine, fine, and medium roots; common very fine irregular pores; 20 percent pebbles; neutral (pH 7.0); gradual wavy boundary. (2 to 7 inches thick)
2C1--16 to 33 inches; pale brown (10YR 6/3) very gravelly loam, brown (10YR 5/3) moist; massive; hard, firm, moderately sticky and moderately plastic; few very fine, fine, and medium roots; few very fine irregular pores; 45 percent pebbles and 10 percent cobbles; strongly effervescent; slightly alkaline (pH 7.6); clear wavy boundary. (15 to 20 inches thick)
2C2--33 to 53 inches; light brownish gray (2.5Y 6/2) extremely gravelly loam, grayish brown (2.5Y 5/2) moist; massive; hard, firm, slightly sticky and moderately plastic; few fine medium and coarse roots; few very fine irregular pores; 50 percent pebbles, 10 percent cobbles, and 5 percent stones; violently effervescent; slightly alkaline (pH 7.4); clear wavy boundary.
2R--53 inches: limestone.
TYPE LOCATION: Pend Oreille County, Washington; 1,400 feet north and 660 feet east of the southwest corner of section 15, T. 40 N., R. 44 E., WM.
RANGE IN CHARACTERISTICS: The mean annual soil temperature at 20 inches ranges from 45 to 47 degrees F. The soil is usually moist but is dry in all parts between depths of 4 and 12 inches for 45 to 60 consecutive days following the summer solstice. The ash mantle is 7 to 14 inches thick. The particle-size control section averages between 35 and 85 percent coarse fragments and has free carbonates in the lower part.
The Bw horizon has hue of 10YR or 7.5YR, value of 5 or 6 dry, 3 through 5 moist, and chroma of 2 through 4 moist and dry. Texture is ashy silt loam or ashy loam. Gravel content ranges from 0 to 10 percent.
The 2BC horizon has value of 5 or 6 dry, 4 or 5 moist, and chroma of 2 through 4 moist and dry. Texture is gravelly silt loam or gravelly loam. Gravel content ranges from 15 to 30 percent. It is neutral or slightly alkaline.
The 2C horizon has hue of 2.5Y or 10YR, value of 5 or 6 dry, 4 or 5 moist, and chroma of 2 through 4 moist and dry. Texture is loam, sandy loam, or coarse sandy loam. Gravel content ranges from 30 to 55 percent, cobbles from 5 to 15 percent, and stones from 0 to 20 percent. It is slightly alkaline or moderately alkaline, and strongly or violently effervescent.
COMPETING SERIES: These are the Belzar, Hartill, Kloochman, Mccree, Newbell, Newhorn, Ohscow, Oxerine, Redriver, Talls, Wilma and Wilmont series. Belzar, Hartill, Kloochman, Oxerine, Redriver, and Wilma soils have a lithic contact at depths of 20 to 40 inches. Inkler, Newbell, Newhorn, Redriver, and Talls soils are neutral or more acid and non-effervescent throughout the control section. Ohscow soils are neutral or slightly acid throughout. Wilmont soils are dry for 60 to 75 consecutive days. Mccree soils are dry for 60 to 75 consecutive days and are neutral or slightly acid throughout.
GEOGRAPHIC SETTING: Threemile soils are on foothills. Slopes are 0 to 65 percent. Elevation ranges from 2,400 to 4,000 feet. The soil developed in calcareous glacial till with a mantle of volcanic ash and loess. The climate is continental having warm, dry summers and cool, moist winters. The average annual precipitation ranges from 25 to 37 inches; and the average annual temperature ranges from 43 to 45 degrees F. The frost-free season ranges from 90 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ahren, Boundary, Kaniksu, Kiehl, and the competing Belzar and Newbell soils. Ahren soils are fine-loamy. Boundary soils have an argillic horizon. Kaniksu soils are sandy. Kiehl soils are sandy-skeletal.
DRAINAGE AND PERMEABILITY: Well drained; slow to very rapid runoff; moderate permeability.
USE AND VEGETATION: Used for grazed woodland, cropland, pasture, and wildlife. Small grains and hay are the principal crops. Native vegetation is Douglas-fir, western larch, western redcedar, lodgepole pine, grand fir, and western hemlock, with an understory of willow, pachystime, Oregon-grape, rose, redstem ceanothus, thimbleberry, western brackenfern, longtube twinflower, and queencup beadlily.
DISTRIBUTION AND EXTENT: Northeastern Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Pend Oreille County Area, Washington, l981.
REMARKS: Diagnostic horizons and features recongnized in this pedon are an ochric epipedon from 1 to 5 inches and a cambic horizon from 5 to 16 inches. The upper 10 inches of the mineral soil is estimated to have a moist bulk density of less than 1.0 g/cc, acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 1.0 to 2.0 percent, and 15-bar water retention of less than 12 percent for air dried samples.