LOCATION HIGHFALLS IDEstablished Series
TAXONOMIC CLASS: Ashy over loamy-skeletal, glassy over mixed, superactive, frigid Alfic Udivitrands
TYPICAL PEDON: Highfalls stony ashy silt loam, bouldery, young forest in burn area; on a south-facing slope of 38 percent at 4,100 feet elevation. When described on May 25, 1995, the soil was moist. (Colors are for dry soil unless otherwise stated.)
Oi--0 to 1.5 inches; needles, leaves, twigs, and bark. (1 to 1.5 inches thick)
Oe--1.5 to 2 inches; decomposed organic matter mixed with Mt. St. Helens volcanic ash. (0.5 to 1 inche thick)
A--2 to 3 inches; grayish brown (10YR 5/2) stony ashy silt loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure parting to weak very fine and fine granular; soft, very friable, nonsticky and slightly plastic; many very fine and fine, few medium roots; many very fine and fine tubular pores; many fine pieces of charcoal; 5 percent gravel, 5 percent cobbles, and 5 percent stones; about 0.1 percent boulders and stones cover surface; slightly acid (pH 6.5); abrupt wavy boundary. (1 to 2 inches thick)
Bw1--3 to 8 inches; yellowish brown (10YR 5/4) stony ashy silt loam, dark yellowish brown (10YR 3/4) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many very fine and fine, common medium, and few coarse roots; many very fine and common fine tubular pores; 5 percent gravel, 5 percent cobbles, and 5 percent stones; slightly acid (pH 6.2); clear wavy boundary. (4 to 8 inches thick)
Bw2--8 to 18 inches; light yellowish brown (10YR 6/4) stony ashy silt loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many very fine, common fine and medium, few coarse roots; many very fine and common fine tubular pores; 5 percent gravel, 5 percent cobbles, and 5 percent stones; neutral (pH 7.0); clear wavy boundary. (6 to 10 inches thick)
2Bt--18 to 29 inches; very pale brown (10YR 7/3) very gravelly sandy loam, brown (10YR 5/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, nonsticky and slightly plastic; common very fine and few fine roots; many very fine and few fine tubular pores; few faint clay films on faces of peds and lining pores; 30 percent gravel, 5 percent cobbles, and 5 percent stones; slightly acid (pH 6.5); clear wavy boundary. (10 to 14 inches thick)
2C--29 to 60 inches; pale yellow (2.5Y 8/3) very cobbly fine sandy loam, light yellowish brown (2.5Y 6/3) moist; massive; slightly hard, friable, nonsticky and slightly plastic; few very fine roots; common very fine and few fine tubular and irregular pores; 30 percent gravel, 25 percent cobbles, and 5 percent stones; neutral (pH 6.8).
TYPE LOCATION: Boundary County, Idaho; about 6.75 miles northwest of Naples; about 2,600 feet south and 1,800 feet east of the northwest corner of sec. 17, T. 61 N., R. 1 W.;
Latitude - 48 degrees, 38 minutes, 15 seconds North;
Longitude - 116 degrees, 29 minutes, 25 seconds West.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 43 to 46 degrees F.
Average summer soil temperature - 49 to 53 degrees F. with an O horizon.
Moisture control section - dry 30 to 45 days (August to September), moist mid-September through July.
Clay content - 3 to 8 percent in particle-size control section.
Surface boulders and stones - 0 to 3 percent.
Volcanic ash mantle - 14 to 20 inches thick.
Volcanic glass content - 30 to 65 percent.
Acid-Oxalate extractable Al + 1/2 Fe - 1.0 to 3.0 percent.
Phosphate retention - 55 to 90 percent.
15 bar water (air dried) - 7 to 12 percent.
A horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 1 through 3 dry or moist
Texture - ST-SIL, SIL, GR-SIL (ashy)
Gravel content - 0 to 20 percent
Cobble content - 0 to 5 percent
Stone and boulder content - 0 to 5 percent
Bulk density - 0.65 to 0.90 g/cc
Reaction - slightly acid or neutral
Bw horizons
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 4 or 6 dry or moist
Texture - ST-SIL, SIL, GR-SIL (ashy)
Gravel content - 5 to 25 percent
Cobble content - 0 to 10 percent
Stone content - 0 to 15 percent
Bulk density - 0.65 to 0.90 g/cc
Reaction - slightly acid or neutral
2Bt horizon
Hue - 10YR or 2.5Y
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 3 or 4 dry or moist
Texture - GRV-SL, CBV-SL, CBV-FSL
Gravel content - 10 to 30 percent
Cobble content - 5 to 35 percent
Stone content - 0 to 10 percent
Reaction - slightly acid or neutral
2C horizon
Value - 6 to 8 dry, 4 to 6 moist
Chroma - 3 or 4 dry or moist
Texture - CBV-FSL, GRV-SL, CBV-SL, GRV-FSL
Gravel content - 15 to 35 percent
Cobble content - 15 to 40 percent
Stone content - 0 to 15 percent
Reaction - slightly acid or neutral
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Highfalls soils are mostly on south and west-facing mountain slopes, foothills, and footslopes. Slopes range from 5 to 65 percent. They formed in glacial till derived from granite, gneiss, and schist with a thick mantle of volcanic ash. Elevations range from 2,800 to 5,000 feet. The average annual air temperature ranges from 43 to 46 degrees F. and the average annual precipitation ranges from 30 to 50 inches. The average frost-free period is 80 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Idamont, Pearsoncreek (T), Pend Oreille, Rubycreek (T), and Treble soils. Idamont soils are on east and west-facing mountain and foothill slopes and are ashy over loamy. Pearsoncreek soils are on south-facing mountain and foothill slopes and have a volcanic ash mantle less than 14 inches thick. Pend Oreille soils are on north-facing mountain and foothill slopes and are ashy over loamy. Rubycreek soils are on mountain slopes at higher elevations and are cryic. Treble soils are on south-facing mountain and foothill slopes, are dry more than 45 days, and contain less volcanic ash.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate permeability in the upper part and moderately rapid below.
USE AND VEGETATION: These soils are used for timber production, wildlife habitat, recreation, and watershed. Natural vegetation is mainly grand fir, Douglas-fir, western white pine, western larch, and lodgepole pine with an understory of Saskatoon serviceberry, baldhip rose, pine reedgrass, white spirea, longtube twinflower, russet buffaloberry, creambush oceanspray, low Oregongrape, common snowberry, common princes pine, queencup beadlily, Rocky Mountain maple, and darkwoods violet.
DISTRIBUTION AND EXTENT: Northern Idaho, and possibly northwestern Montana and northeastern Washington. This series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Boundary County, Idaho, 2002.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the mineral soil surface to 7 inches (A and part of Bw1 horizon)
Cambic horizon - the zone from 3 to 18 inches (Bw1 and Bw2 horizons)
Argillic horizon - the zone from 18 to 29 inches (2Bt horizon)
Volcanic ash mantle - the zone from 2 to 18 inches (A, Bw1, and Bw2 horizons)
Particle-size control section - the zone from 2 to 42 inches (A, Bw1, Bw2, 2Bw3, and part of the 2C horizon)