LOCATION LARCHPOINT MTEstablished Series
TAXONOMIC CLASS: Coarse-loamy over sandy or sandy-skeletal, mixed, superactive, acid, frigid Typic Endoaquents
TYPICAL PEDON: Larchpoint silt loam (colors are for moist soil unless otherwise noted).
A--0 to 7 inches; very dark grayish brown (10YR 3/2) silt loam, light brownish gray (10YR 6/2) dry; weak fine granular structure; soft, friable, nonsticky and nonplastic; many very fine and fine roots; 10 percent pebbles; strongly acid (pH 5.2); clear smooth boundary. (3 to 8 inches thick)
C--7 to 15 inches; very dark grayish brown (2.5Y 3/2) silt loam, light brownish gray (2.5Y 6/2) dry; weak coarse prismatic structure parting to moderate medium subangular blocky; soft, friable, slightly sticky and slightly plastic; many very fine and fine roots; common fine distinct dark yellowish brown (10YR 4/6) redox concentrations; 10 percent pebbles; strongly acid (pH 5.4); gradual wavy boundary. (5 to 12 inches thick)
Cg--15 to 27 inches; gray (5Y 5/1) silt loam, light gray (5Y 7/1) dry; massive; soft, friable, nonsticky and nonplastic; common very fine and fine roots; common fine distinct dark yellowish brown (10YR 4/6) redox concentrations; 10 percent pebbles; strongly acid (pH 5.4); gradual wavy boundary. (6 to 14 inches thick)
2Cg--27 to 31 inches; dark greenish gray (5GY 4/1) loamy coarse sand, light greenish gray (5GY 7/1) dry; single grain; loose; few very fine roots; common fine distinct dark yellowish brown (10YR 4/6) redox concentrations; 10 percent pebbles; strongly acid (pH 5.4); gradual wavy boundary. (3 to 8 inches thick)
3Cg--31 to 60 inches; gray (5Y 6/1) very gravelly loamy coarse sand, light gray (5Y 7/1) dry; single grain; loose; few very fine roots; common fine distinct dark yellowish brown (10YR 4/6) redox concentrations; 10 percent cobbles, 40 percent pebbles; strongly acid (pH 5.4).
TYPE LOCATION: Sanders County, Montana; 600 feet west and 1800 feet south of the northeast corner of section 3, T. 22N., R. 31W.
RANGE IN CHARACTERISTICS:
Soil temperature - 44 to 47 degrees F.
Depth to seasonal high water table - 12 to 24 inches.
A horizon - Value: 5, 6, or 7 dry, 3, 4, or 5 moist
Clay content: 8 to 18 percent
Rock fragments: 0 to 10 percent pebbles
Reaction: 4.5 to 5.5
C horizon - Hue: 2.5Y or 10YR
Value: 5, 6, or 7 dry, 4, 5, or 6 moist
Clay content: 8 to 18 percent
Rock fragments: 0 to 10 percent pebbles
Reaction: 4.5 to 5.5
Cg horizon - Hue: 5GY or 5Y
Value: 6 or 7 dry, 4 or 5 moist
Clay content: 8 to 18 percent
Rock fragments: 0 to 10 percent pebbles
Reaction: 4.5 to 5.5
2Cg horizon - Hue: 5GY or 5Y
Value: 6 or 7 dry, 4 or 5 moist
Clay content: 2 to 10 percent
Rock fragments: 0 to 10 percent pebbles
Reaction: 4.5 to 5.5
3Cg horizon - Hue: 5GY or 5Y
Value: 6 or 7 dry, 4, 5 or 6 moist
Clay content: 2 to 10 percent clay
Rock fragments: 35 to 60 percent; 0 to 15 percent cobbles, 35 to 45 percent pebbles
Reaction: 4.5 to 5.5
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - floodplains.
Elevation - 2,200 to 4,200 feet.
Slope- 0 to 2 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: Poorly drained, moderate over rapid permeability.
USE AND VEGETATION: Larchpoint soils are used mainly for grazing and wildlife habitat. Potential native vegetation is mainly black cottonwood, Engelmann spruce, sedges, cinquefoil, timothy, and reed canarygrass.
DISTRIBUTION AND EXTENT: Larchpoint 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 Interpretation Record: MT1385. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches (A horizon); lithologic discontinuities at depths of 27 and 31 inches; redoximorphic features below a depth of 15 inches (Cg, 2Cg, and 3Cg horizons); a particle size control section from 10 to 40 inches (C, Cg, 2Cg, and 3Cg horizons). Larchpoint soils have an aquic moisture regime and a frigid temperature regime.
ADDITIONAL DATA: S92MT-089-011