LOCATION TREBLE ID+MT

Established Series
Rev. SMM-SHB-RJS
05/2017

TREBLE SERIES

The Treble series consists of very deep, well drained soils on mountains, foothills and escarpments. They formed in till derived from granite, gneiss, and schist with a thin mantle of loess and volcanic ash. Slope ranges from 5 to 65 percent. The average annual precipitation is about 660 mm and, mean annual air temperature is about 7.8 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, active, frigid Vitrandic Haploxerepts

TYPICAL PEDON: Treble gravelly ashy sandy loam, forested; on a south-facing slope of 30 percent at 765 meters 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.)

Oi--0 to 3 cm; needles, leaves, and twigs. (0.5 to 3 cm thick)

Oe--3 to 5 cm; partially decomposed needles, leaves and twigs. (0.5 to 3 cm thick)

A--5 to 10 cm; 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. (3 to 10 cm thick)

Bw1--10 to 20 cm; 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. (8 to 15 cm thick)

Bw2--20 to 36 cm; 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. (13 to 25 cm thick)

Bt1--36 to 61 cm; 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. (20 to 41 cm thick)

Bt2--61 to 86 cm; 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. (20 to 25 cm thick)

Bt3--86 to 152 cm; 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 7.2 km west of Bonners Ferry on the Myrtle Creek-Cascade Creek road; about 713 meters south and 469 meters 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:
Mean annual soil temperature -- 6.7 to 7.8 degrees C
Mean summer soil temperature -- 12.2 to 13.3 degrees C. with an O 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 -- 0.6 to 1.3 cm thick between O and A horizons in some pedons in undisturbed areas
Surface stones and boulders -- 0 to 3 percent

Volcanic ash (estimated properties)
Thickness -- 25 to 50 cm
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 dry or moist
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): 0.2 to 2 cm thick
Reaction: moderately acid to slightly acid

C horizon (present in some pedons)
Hue: 10YR or 2.5Y dry or moist
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:
Landform: mountain slopes, foothills, escarpments
Elevation: 550 to 1160 meters
Slope: 5 to 65 percent
Parent material: till derived from granite, gneiss, and schist with a thin mantle of loess and volcanic ash
Mean annual precipitation: 600 to 1,150 mm
Mean annual air temperature: 5.6 to 7.8 degrees C
Frost free period: 80 to 130 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bonner, Dufort, Idamont, Kriest, and Pend Oreille soils. Bonner soils are on outwash terraces and have a thick volcanic ash mantle on the surface. 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 weathered bedrock at 100 to 150 cm.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; runoff is medium to very rapid; saturated hydraulic conductivity is moderately high.

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. MLRAs -- 43A, 44A.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Boundary County, Idaho, 1974.

REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon -- 0 to 10 cm (Oi, Oe, A horizons);
Cambic horizon -- 10 to 152 cm (Bw1, Bw2, Bt1, Bt2, Bt3 horizons); and
Particle-size control section -- 30 to 105 cm (part of Bw2, Bt1, Bt2, part of Bt3 horizons)

ADDITIONAL DATA: Partial KSSL data available for this pedon; Soil Survey Sample Number: S1993ID021005 Boundary County, Idaho. KSSL Pedon Number: 94P0244

Re-classified (5/24/2017) from "Loamy-skeletal, mixed, superactive, frigid Vitrandic Dystroxerepts" to "Loamy-skeletal, mixed, active, frigid Vitrandic Haploxerepts".

National Cooperative Soil Survey
U.S.A.