LOCATION LOONLAKE MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Andic Paleudalfs
TYPICAL PEDON: Loonlake gravelly ashy silt loam, forested (colors are for dry soil unless otherwise noted).
Oi--0 to 2 inches; undecomposed and slightly decomposed forest litter. (1 to 2 inches thick)
Bw--2 to 11 inches; light yellowish brown (10YR 6/4) gravelly ashy silt loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure parting to moderate fine granular; slightly hard, very friable, slightly sticky and slightly plastic; common fine and medium and few coarse roots; 15 percent gravel; moderately acid (ph 6.0); clear wavy boundary. (7 to 10 inches thick)
2E--11 to 26 inches; very pale brown (10YR 7/3) very gravelly sandy loam, brown (10YR 5/3) moist; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common fine and medium and few coarse roots; 10 percent cobbles, 35 percent gravel; moderately acid (ph 6.0); gradual wavy boundary. (10 to 20 inches thick)
2E/Bt--26 to 38 inches; E part (80 percent) is very pale brown (10YR 7/3) extremely cobbly sandy loam, brown (10YR 5/3) moist, Bt part (20 percent) is pale brown (10YR 6/3) extremely cobbly sandy clay loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and medium and few coarse roots; 30 percent cobbles, 40 percent gravel; moderately acid (ph 6.0); gradual wavy boundary. (10 to 15 inches thick)
2Bt--38 to 60 inches; pale brown (10YR 6/3) very gravelly sandy clay loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common medium and few coarse roots; continuous faint clay films on faces of peds; 10 percent cobbles, 40 percent gravel; slightly acid (ph 6.4).
TYPE LOCATION: Lincoln County, Montana; 700 feet west and 1,800 feet north of the SE corner of sec. 22, T. 27 N., R. 28 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 44 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Depth to argillic horizon - 27 to 38 inches.
Bw horizon - Value: 5 or 6 dry, 4 or 5 moist
Clay content: 5 to 15 percent
Rock fragments: 15 to 25 percent--0 to 5 percent cobbles, 15 to 20 percent gravel
Acid oxalate (Al + 1/2 Fe): 1.0 to 1.2 percent
Bulk density: .85 to 1.0 g/cc
Reaction: pH 5.6 to 7.3
2E horizon - Value: 6 or 7 dry, 5 or 6 moist
Clay content: 5 to 15 percent
Rock fragments: 35 to 50 percent--5 to 15 percent cobbles, 30 to 35 percent gravel
Reaction: pH 5.6 to 7.3
2E/Bt horizon - Value: E part 6 or 7, Bt part 5 or 6 dry; E part 4, 5, or 6, Bt part 4 or 5 moist
Clay content: E part 5 to 15 percent, Bt part 20 to 25 percent
Rock fragments: 60 to 80 percent--20 to 35 percent cobbles, 35 to 45 percent gravel
Reaction: pH 5.6 to 7.3
2Bt horizon - Value: 5 or 6 dry, 4 or 5 moist
Clay content: 20 to 30 percent
Rock fragments: 40 to 60 percent--5 to 20 percent cobbles, 30 to 40 percent gravel
Reaction: 5.6 to 7.3
COMPETING SERIES:
Loneman (MT) - has less than 60 percent coarse fragments in the particle-size control section; formed in colluvium.
Noxlin (MT) - has less than 60 percent coarse fragments in the particle-size control seciton; has a glossic horizon below a depth of 30 inches.
GEOGRAPHIC SETTING:
Landforms- outwash plains and stream terrace in valleys.
Elevation - 3,300 to 3,800 feet.
Slope - 0 to 30 percent.
Parent material - volcanic ash over glacial outwash.
Climate - long, cold winters; moist springs; warm, dry summers.
Mean annual precipitation - 24 to 30 inches, much of which falls as snow and spring rains.
Mean annual air temperature - 40 to 45 degrees F.
Frost-free period - 70 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS:
DRAINAGE AND PERMEABILITY: Well drained, moderate permeability.
USE AND VEGETATION: Loonlake soils are used mainly for woodland, understory grazing, and wildlife habitat. Potential native vegetation is mainly ponderosa pine, Douglas fir, western larch, lodgepole pine, grand fir, and Engelmann spruce. Understory vegetation is mainly pinegrass, russet buffaloberry, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Loonlake soils are of small extent in the valleys of northwestern Montana. MLRA 44A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Lincoln County, Montana, 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ash influenced layer - 2 to 11 inches (Bw horizon);
Argillic horizon - 38 to 60 inches (2Bt horizon);
Particle-size control section - 38 to 58 inches (2Bt horizon).
Loonlake soils have a frigid temperature regime and a udic moisture regime that borders on ustic.
ADDITIONAL DATA: Laboratory data S92MT-053-003; Soil interpretation record: MT1359..