LOCATION PAX MTEstablished Series
TAXONOMIC CLASS: Ashy, glassy, frigid Vitrandic Haplustalfs
TYPICAL PEDON: Pax very cobbly ashy sandy loam, in forest (colors are for dry soil unless otherwise noted).
Oi--0 to 0.5 inch; partially decomposed needles, twigs and leaves.
E--0.5 to 8 inches; brown (7.5YR 5/2) very cobbly ashy sandy loam, brown (7.5YR 4/2) moist; moderate very fine and fine granular structure; slightly hard, very friable, slightly sticky and nonplastic; many very fine and fine roots and few medium roots; 25 percent cobbles and 20 percent pebbles; neutral (pH 7.2); clear wavy boundary. (4 to 9 inches thick)
Bt--8 to 15 inches; brown (7.5YR 5/2) gravelly ashy sandy clay loam, brown (7.5YR 4/2) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots and few medium roots; many medium tubular pores; few faint clay films on faces of peds; 5 percent cobbles and 15 percent pebbles; slightly alkaline (pH 7.4); gradual wavy boundary. (6 to 14 inches thick)
BC--15 to 27 inches; pinkish gray (5YR 6/2) ashy coarse sandy loam, reddish brown (5YR 4/3) moist; weak medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; many very fine and fine roots, few medium and coarse roots; common medium tubular pores; 5 percent pebbles; slightly alkaline (pH 7.6); gradual wavy boundary. (5 to 15 inches thick)
Cr--27 to 60 inches; pinkish gray (5YR 7/2) decomposing welded tuff bedrock.
TYPE LOCATION: Deer Lodge County, Montana; 1300 feet east and 1350 feet south of the NW corner of sec. 1, T. 3 N., R. 11 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 38 to 41 degrees F.
Moisture control section - between 4 and 12 inches.
Volcanic glass - 30 to 50 percent in the coarse silt and sand fraction.
Acid oxalate Al + 1/2 Fe - .12 to .20 percent.
Depth to argillic horizon - 4 to 10 inches.
Depth to Cr horizon - 20 to 40 inches.
E horizon - Hue: 7.5YR, 10YR or 2.5Y
Value: 4 or 5 dry; 2, 3 or 4 moist
Chroma: 1 or 2
Clay content: 15 to 20 percent
Rock fragments: 35 to 50 percent--20 to 30 percent cobbles and stones, 15 to 20 percent pebbles
Reaction: pH 6.1 to 7.8
Bt horizon - Hue: 7.5YR, 10YR or 2.5Y
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2, 3 or 4
Texture: ashy loam, ashy clay loam or ashy sandy clay loam
Clay content: 23 to 30 percent
Rock fragments: 5 to 35 percent--0 to 10 percent cobbles and stones, 5 to 25 percent pebbles
Reaction: pH 6.1 to 7.8
BC horizon - Hue: 5YR, 7.5YR, 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2, 3 or 4
Texture: ashy loam, ashy sandy loam, ashy coarse sandy loam or ashy sandy clay loam
Clay content: 15 to 25 percent
Rock fragments: 5 to 35 percent--0 to 10 percent cobbles and stones; 5 to 25 percent pebbles
Reaction: pH 6.1 to 7.8
COMPETING SERIES:
Caramon (MT) - has more than 35 percent clay in the particle-size control section.
GEOGRAPHIC SETTING:
Landform - hills; mountains.
Elevation - 5,300 to 6,900 feet.
Slope - 4 to 60 percent.
Parent material - alluvium, colluvium and residuum from welded tuff or rhyolite.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 18 to 24 inches.
Mean annual air temperature - 36 to 39 degrees F.
Frost-free period - 70 to 90 days.
DRAINAGE AND PERMEABILITY: Well drained, moderate permeability.
USE AND VEGETATION: Pax soils are mainly used for woodland, understory grazing, watershed, and wildlife habitat. The potential native vegetation is mainly lodgepole pine, Douglas-fir, Rocky Mountain juniper, limber pine, Oregongrape, common snowberry, bitterbrush, quaking aspen, sandberg bluegrass, tufted hairgrass, bluebunch wheatgrass, Idaho fescue, lupine and rose.
DISTRIBUTION AND EXTENT: Pax soils are of small extent in southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Deer Lodge County, Montana, 1999.
REMARKS: Soil interpretive record: MT1746. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the mineral surface to 8 inches (E horizon); an argillic horizon from 8 to 15 inches (Bt horizon); a particle size control section from 8 to 15 inches (Bt horizon); a layer of decomposing welded tuff from 27 to 60 inches (Cr horizon). Pax soils have a frigid temperature regime and an ustic moisture regime.