LOCATION OLDTRAIL MTEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, mixed, frigid Oxyaquic Udifluvents
TYPICAL PEDON: Oldtrail gravelly sandy loam, in coniferous forest (colors are for moist soil unless otherwise noted).
A--0 to 4 inches, very dark grayish brown (10YR 3/2) gravelly sandy loam, grayish brown (10YR 5/2) dry; weak very fine granular structure; slighly hard, friable, nonsticky and nonplastic; many very fine and common fine roots; 5 percent cobbles, 30 percent pebbles; moderately acid (pH 5.6); clear wavy boundary. (3 to 6 inches thick)
C1--4 to 12 inches, dark grayish brown (10YR 4/2) extremely gravelly loamy coarse sand, light brownish gray (10YR 6/2) dry; single grain; loose; nonsticky and nonplastic; common fine and very fine roots; 20 percent cobbles and 50 percent pebbles; moderately acid (pH 5.6); abrupt wavy boundary. (6 to 12 inches thick)
C2--12 to 25 inches, dark grayish brown (10YR 4/2) extremely cobbly loamy coarse sand, with thin strata of sand; light brownish gray (10YR 6/2) dry; single grain; loose; nonsticky and nonplastic; few very fine roots; 40 percent cobbles and 30 percent pebbles; moderately acid (pH 5.6); gradual wavy boundary. (0 to 15 inches thick)
C3--25 to 60 inches, stratified dark grayish brown (10YR 4/2) extremely cobbly loamy coarse sand, light brownish gray (10YR 6/2) dry, and very dark grayish brown (10YR 3/2) extremely gravelly loamy coarse sand, grayish brown (10YR 5/2) dry; single grain; loose; nonsticky and nonplastic; few very fine roots; 40 percent cobbles and 30 percent pebbles; moderately acid (pH 5.6).
TYPE LOCATION: Sanders County, Montana; 100 feet north and 100 feet west of the center of sec. 33, T. 26 N., R. 33 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 45 degrees F.
Depth to seasonal high water table - 2 to 3.5 feet some time during the period from April to June.
The surface layer will not meet the requirements of a mollic epipedon.
The C3 horizon is stratified, but averages extremely cobbly.
A horizon - Value: 3 or 4 moist; 5 or 6 dry
Chroma: 2 or 3
Clay content: 0 to 10 percent
Rock fragments: 15 to 35 percent--0 to 5 percent cobbles, 15 to 30 percent pebbles
Reaction: pH 5.6 to 6.5
C1 horizon - Value: 4 or 5 moist; 6 or 7 dry
Chroma: 2 or 3
Texture: loamy coarse sand, coarse sandy loam
Clay content: 0 to 5 percent
Rock fragments: 60 to 80 percent--10 to 20 percent cobbles, 50 to 60 percent pebbles
Reaction: pH 5.6 to 6.5
C2 and C3 horizons - Value: 3, 4, or 5 moist; 5, 6 or 7 dry
Chroma: 2 or 3
Texture: loamy coarse sand, loamy sand, coarse sand
Clay content: 0 to 5 percent
Rock fragments: 60 to 80 percent--30 to 40 percent cobbles, 30 to 40 percent pebbles
Reaction: pH 5.6 to 6.5
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - floodplains and drainageways in steep narrow mountain valleys.
Elevation - 2200 to 4200 feet.
Slope- 0 to 8 percent.
Parent material - alluvium.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 20 to 34 inches.
Mean annual temperature - 42 to 45 degrees F.
Frost-free period - 70 to 105 days.
DRAINAGE AND PERMEABILITY: Moderately well drained; rapid permeability.
USE AND VEGETATION: Oldtrail soils are used mainly for watershed protection and wildlife habitat. Potential native vegetation is mainly aspen, black cottonwood, Douglas-fir, Engelmann spruce, grand fir, mountain maple, serviceberry, thin-leaf alder, common snowberry, woods rose, western yarrow, oregon-grape, and elk sedge.
DISTRIBUTION AND EXTENT: Oldtrail soils are of small extent in the valleys of northwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Sanders County, Montana 1997.
REMARKS: Soil Interpretations Records: MT1515. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches mixed (A, C1 horizons); a particle-size control section from 10 to 40 inches (C1, C2, C3 horizons). Oldtrail soils have a frigid temperature regime and a udic moisture regime.
ADDITIONAL DATA: Lab data S94MT-089-004