LOCATION WEBBRIDGE IDEstablished Series
TAXONOMIC CLASS: Ashy over loamy-skeletal, isotic Alfic Vitricryands
TYPICAL PEDON: Webbridge ashy silt loam - on north-facing concave slope of 52 percent at an elevation of 4,520 feet in forest. (Colors are for dry soil unless otherwise noted. When described on July 29, 1991, the soil was moist throughout.)
Oi--0 to 1 inch; slightly decomposed twigs, moss, and needles.
A--1 to 4 inches; light yellowish brown (10YR 6/4) ashy silt loam, dark yellowish brown (10YR 3/4) moist; weak fine granular structure; soft, very friable, nonsticky and slightly plastic; many fine and very fine roots; many fine and very fine irregular pores; less than 5 percent fine gravel; moderately acid (pH 6.0); clear smooth boundary. (1 to 3 inches thick)
Bw1--4 to 11 inches; light yellowish brown (10YR 6/4) ashy silt loam, dark yellowish brown (10YR 3/4) moist; weak coarse subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many fine and very fine and few medium roots; many fine and very fine tubular pores; 10 percent fine gravel; moderately acid (pH 5.9); gradual smooth boundary.
Bw2--11 to 18 inches; light yellowish brown (10YR 6/4) ashy silt loam, dark yellowish brown (10YR 4/4) moist; weak coarse subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many fine and very fine and few medium roots; many fine and very fine tubular pores; 10 percent fine gravel; moderately acid (pH 5.9); abrupt irregular boundary. (combined thickness of the Bw1 and Bw2 horizons is 12 to 22 inches)
2Btb1--18 to 25 inches; yellowish brown (10YR 5/4), yellowish brown (10YR 5/6) crushed cobbly clay loam, dark brown (7.5YR 3/4) moist; moderate medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common fine and very fine and few medium roots; common fine and very fine tubular pores; very few faint patchy yellowish brown (10YR 5/4) clay films on faces of peds; 10 percent gravel, 15 percent cobbles, 5 percent stones; moderately acid (pH 5.7); gradual wavy boundary.
2Btb2--25 to 35 inches; yellowish brown (10YR 5/4), yellowish brown (10YR 5/6) crushed very cobbly clay loam, dark brown (7.5YR 3/4) moist; moderate medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common fine and very fine and few medium roots; many fine and very fine tubular pores; very few faint patchy yellowish brown (10YR 5/4) clay films on faces of peds; 15 percent gravel, 25 percent cobbles, 5 percent stones; moderately acid (pH 5.7); clear wavy boundary. (combined thickness of the 2Btb1 and 2Btb2 horizons is 12 to 25 inches)
2Btb3--35 to 46 inches; yellowish brown (10YR 5/4), light yellowish brown (10YR 6/4) crushed extremely cobbly loam, dark brown (7.5YR 3/4) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common fine roots; many fine and very fine tubular pores; very few faint patchy yellowish brown (10YR 5/4) clay films on faces of peds; 30 percent gravel, 40 percent cobbles, 5 percent stones; neutral (pH 6.6); clear smooth boundary.
2Btb4--46 to 54 inches; yellowish brown (10YR 5/4), light yellowish brown (10YR 6/4) crushed extremely cobbly loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; few fine roots matted around rock fragments; common fine and very fine tubular pores; 30 percent gravel, 55 percent cobbles, 5 percent stones; slightly acid (pH 6.5); clear smooth boundary. (combined thickness of the 2Btb3 and 2Btb4 horizons is 12 to 30 inches)
2R--54 inches; basalt.
TYPE LOCATION: Nez Perce County, Idaho; about 3 miles southeast of Waha, about 1,300 feet south and 2,570 feet east of the northwest corner of section 26, T. 33 N., R. 4 W.; USGS Waha topographic quadrangle; lat. 46 degrees 10 minutes 45 seconds N., long. 116 degrees 48 minutes 07 seconds W.
RANGE IN CHARACTERISTICS:
Depth to bedrock - 40 to 60 inches
Average annual soil temperature - 42 to 45 degrees F.
Average summer soil temperature - 52 to 54 degrees F. (without and O horizon)
Volcanic ash mantle:
Thickness - 14 to 24 inches
Volcanic glass content, 0.02 to 2mm fraction - 25 to 45 percent
Ammonium-oxalate extractable Al plus 1/2 Fe - 1.0 to 2.0 percent
Moist bulk density - .75 to .90 g/cc
15-bar water retention on air dry soil - 8 to 12 percent
Particle-size control section, lower part (weighted averages):
Clay content - 25 to 32 percent
Coarse fragment content - 40 to 60 percent
A horizon
Hue - 7.5YR or 10YR
Value - 4 or 5 dry, 3 or 4 moist
Reaction - slightly acid or neutral
Bw horizon
Hue - 7.5YR or 10YR
Value - 5 or 6 dry, 3 or 4 moist
Gravel content - 5 to 25 percent, mostly fine gravel
Reaction - moderately acid or slightly acid
2Btb horizon, upper part
Hue - 7.5YR or 10YR
Value - 4 through 6 dry, 3 or 4 moist
Texture - CB-CL, CBV-CL, GRV-L, GRV-CL, GR-CL
Rock fragment content - 25 to 50 percent
Clay content - 25 to 32 percent
Reaction - moderately acid or slightly acid
2Btb horizon, lower part
Hue - 5YR, 7.5YR, or 10YR
Value - 4 through 6 dry, 3 or 4 moist
Chroma - 4 through 6, dry or moist
Texture - CBX-L, CBV-CL, GRV-CL, GRV-L
Rock fragment content - 40 to 90 percent
Clay content - 25 to 32 percent
Reaction - moderately acid to neutral
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Webbridge soils are on steep or very steep canyon sides at elevations of 3,900 to 5,000 feet. Slope ranges from 35 to 75 percent. The soils formed in a mantle of volcanic ash over colluvium from basalt. The average annual precipitation is 27 to 29 inches. The frost-free period is 60 to 70 days. The average annual air temperature is about 41 to 43 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Agatha, Cramont, and Shilla soils. Agatha soils are on south- and west-facing canyon sides, are frigid and xeric, and do not have a volcanic ash mantle. Cramont soils are on plateaus, are frigid and xeric, do not have a thick ash mantle, and have a clayey subsoil. Shilla soils are on plateaus, have an argillic horizon, and are frigid and xeric.
DRAINAGE AND PERMEABILITY: Well-drained, slow to medium runoff, moderately slow permeability.
USE AND VEGETATION: Used mainly for woodland, woodland grazing, recreation, and wildlife habitat. The natural vegetation is mainly grand fir, Douglas-fir, Engelmann spruce, queencup beadlily, goldthread, longtube twinflower, and onesided wintergreen.
DISTRIBUTION AND EXTENT: North central Idaho. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Nez Perce County, Idaho, 1995.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Ochric epipedon - from the surface to 7 inches mixed (Oi, A, and part of the Bw1 horizon)
Andic materials - from the mineral surface to 17 inches (A, Bw1, and Bw2 horizons)
Argillic horizon - from 18 to 54 inches (2Btb1, 2Btb2, 2Btb3 and 2Btb4 horizons)
Particle-size control section - the zone from the mineral surface to 40 inches (A, Bw1, Bw2, 2Btb1, 2Btb2, and part of the 2Btb3 horizon)
Lithic contact - at 54 inches
ADDITIONAL DATA: This pedon has been sampled by the NSSL. Laboratory sample number 91P1095; soil survey sample number S91ID-069-030.