LOCATION TREBLE ID+MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Vitrandic Dystroxerepts
TYPICAL PEDON: Treble gravelly ashy sandy loam, forested; on a south-facing slope of 30 percent at 2,650 feet elevation. When described on August 22, 1972, the soil was dry throughout. Pedon was redescribed on July 29, 1996. (Colors are for dry soil unless otherwise stated.)
0i--0 to 1 inch; needles, leaves, and twigs. (0.5 to 1 inch thick)
0e--1 to 2 inches; partially decomposed needles, leaves and twigs. (0.5 to 1 inch thick)
A--2 to 4 inches; dark yellowish brown (10YR 4/4) gravelly ashy sandy loam, very dark brown (10YR 2/2) moist; moderate very fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine, fine, and common medium roots; many fine pores; 25 percent gravel; neutral (pH 6.9); abrupt wavy boundary. (1 to 4 inches thick)
Bw1--4 to 8 inches; brown (7.5YR 4/4) gravelly ashy sandy loam, dark brown (7.5YR 3/3) moist; weak medium subangular blocky structure parting to moderate medium granular; slightly hard, friable, slightly sticky and slightly plastic; many fine and medium roots; common fine pores; 25 percent gravel; slightly acid (pH 6.5); clear wavy boundary. (3 to 6 inches thick)
Bw2--8 to 14 inches; yellowish brown (10YR 5/4) gravelly ashy sandy loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine pores; 30 percent gravel; slightly acid (pH 6.1); clear wavy boundary. (5 to 10 inches thick)
Bt1--14 to 24 inches; light yellowish brown (10YR 6/4) very gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; moderate coarse subangular blocky structure; hard, firm, slightly sticky and slightly plastic; few very fine, fine, and medium roots; many very fine and few fine pores; few faint clay films; 40 percent gravel; moderately acid (pH 5.9); clear wavy boundary. (8 to 16 inches thick)
Bt2--24 to 34 inches; yellowish brown (10YR 5/4) very gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; weak coarse subangular blocky structure; hard, firm, slightly sticky and slightly plastic; few fine and medium roots; few faint clay films; 55 percent gravel; slightly acid (pH 6.1); clear wavy boundary. (8 to 10 inches thick)
Bt3--34 to 60 inches; yellowish brown (10YR 5/4) very gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; weak coarse subangular blocky structure; hard, firm, slightly sticky and slightly plastic; few fine and medium roots; many very fine and few fine pores; few faint clay films; 35 percent gravel; slightly acid (pH 6.2).
TYPE LOCATION: Boundary County, Idaho; about 4.5 miles west of Bonners Ferry on the Myrtle Creek-Cascade Creek road; about 2,340 feet south and 1,540 feet west of the northeast corner of sec. 23, T. 62 N., R. 1 W.; Latitude - 48 degrees, 42 minutes, 39 seconds North; Longitude - 116 degrees, 25 minutes, 24 seconds West; USGS Moravia Quadrangle.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 44 to 46 degrees F.
Average summer soil temperature - 54 to 56 degrees F. with an 0 horizon
Moisture control section - dry 45 to 60 days (August to September), moist October through July; xeric moisture regime
Base saturation - 35 to 60 percent
Thin light gray volcanic ash layer - 1/4 to 1/2 inch thick between O and A horizons in some pedons in undisturbed areas
Surface stones and boulders - 0 to 3 percent
Volcanic ash influence - 10 to 20 inches thick
Volcanic glass content - 5 to 20 percent
Acid-oxalate extractable Fe + 1/2 Al - 0.4 to 1.0 percent
Moist bulk density - 1.0 to 1.2 g/cc
Phosphate retention - 25 to 55 percent
A horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 to 4 dry, 1 to 3 moist
Texture - GR-ASHY-SL, GR-ASHY-FSL, GR-ASHY-L
Clay content - 3 to 10 percent
Rock fragments - 15 to 25 percent
Reaction - moderately acid to neutral
Bw horizons
Value - 4 to 6 dry, 3 or 4 moist
Chroma - 3 or 4 dry or moist
Texture - GR-ASHY-SL, GR-ASHY-FSL, GR-ASHY-L, and GRV-ASHY-SL lower part in some pedons
Clay content - 3 to 10 percent
Rock fragments - 15 to 30 percent, 35 to 55 percent lower part in some pedons
Reaction - moderately acid to neutral
Bt horizons - absent in some pedons
Hue - 2.5Y, 10YR or 7.5YR
Value - 5 tO 7 dry, 4 or 5 moist
Chroma - 3 or 4 dry or moist
Texture - GRV-SL, GRV-COSL, CBV-SL, CBV-FSL, CBV-L
Clay content - 3 to 10 percent
Rock fragments - 35 to 60 percent
Clay bands - present in some pedons, 1/16 to 3/4 inch thick
Reaction - moderately acid to slightly acid
C horizon - present in some pedons
Hue - 10YR or 2.5Y
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 2 to 4 dry or moist
Texture - GRV-SL, GRV-COSL, GRV-LCOS, GRV-LS, CBV-SL, CBX-SL, GRX-SL
Clay content - 0 to 5 percent
Rock fragments - 35 to 75 percent
Reaction - moderately acid to slightly acid
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Treble soils are on south-facing mountain slopes, foothills, and escarpments. Slopes range from 5 to 65 percent. These soils formed in glacial till derived from mixed sources with minor ammounts of volcanic ash and loess in the surface layers. Elevations range from 1,800 to 3,800 feet. The average annual air temperature ranges from 42 to 46 degrees F. and average annual precipitation ranges from 24 to 35 inches. The average frost-free period is 80 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bonner, Dufort, Idamont, Kriest, and Pend Oreille soils. Bonner soils are on terraces and contain more volcanic ash in the surface layers. Dufort, Idamont, and Pend Oreille soils are on foothills and mountains and contain more volcanic ash in the surface layers. Kriest soils are on mountains and have bedrock at 40 to 60 inches.
DRAINAGE AND PERMEABILITY: Well drained; runoff is medium to very rapid; permeability is moderate to moderately rapid in the upper part and moderately rapid to rapid below.
USE AND VEGETATION: These soils are used for timber production, grazing, wildlife habitat, recreation and watershed. A few areas are used for home-sites. Natural vegetation is mainly Douglas-fir, ponderosa pine, and lodgepole pine with an understory of mallow ninebark, creambush oceanspray, white spirea, Saskatoon serviceberry, largeleaf sandwort, heartleaf arnica, woods rose, pine reedgrass, Columbia brome, common snowberry, strawberry, and elk sedge. The natural vegetation on the high precipitation phase is mainly grand fir, Douglas-fir, western larch, western white pine, and ponderosa pine with an understory of myrtle pachystima, baldhip rose, common snowberry, longtube twinflower, American trailplant, piper anemone, goldthread, elk sedge, pine reedgrass, and starry false Solomons seal.
DISTRIBUTION AND EXTENT: Northern Idaho, northwestern Montana, and possibly northeastern Washington. The series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Boundary County, Idaho, 1974.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 2 to 7 inches (A and part of Bw1 horizons)
Cambic horizon - the zone from 4 to 60 inches (Bw1, Bw2, Bt1, Bt2, and Bt3 horizons)
Particle-size control section - the zone from 12 to 42 inches (part of Bw2, Bt1, Bt2, and part of Bt3 horizon)