LOCATION TORPY MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Ustivitrandic Haplocryepts
TYPICAL PEDON: Torpy gravelly loam, forested, (colors are for dry soil unless otherwise noted).
Oi--0 to 1 inches; forest litter of partially decomposed needles and twigs.
A--1 to 4 inches; dark grayish brown (10YR 4/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate thin platy structure; soft, very friable, nonsticky and slightly plastic; common very fine and fine roots; common very fine and fine pores; 15 percent gravel; moderately acid (pH 6.0); clear smooth boundary. (1 to 3 inches thick)
E--4 to 9 inches; light brownish gray (10YR 6/2) loam, grayish brown (10YR 5/2) moist; weak medium granular structure; soft, very friable, slightly sticky and moderately plastic; common very fine and fine roots; common very fine and fine pores; 10 percent gravel; slightly acid (pH 6.2); gradual smooth boundary. (0 to 6 inches thick)
Bw--9 to 35 inches; light gray (10YR 7/2) very cobbly loam, grayish brown (10YR 5/2) moist; moderate medium angular blocky structure; soft, very friable, slightly sticky and moderately plastic; common very fine and few fine roots; common very fine and fine pores; 25 percent gravel, 20 percent cobbles; slightly acid (pH 6.4); gradual smooth boundary. (20 to 30 inches thick)
BC--35 to 61 inches; light gray (10YR 7/1) very cobbly loam, gray (10YR 5/1) moist; single grain; loose, slightly sticky and slightly plastic; 25 percent gravel, 25 percent cobbles; few coarse roots; slightly acid (pH 6.5).
TYPE LOCATION: Jefferson County, Montana; 2,600 feet east and 200 feet south of the NW corner of sec. 19, T. 6 N., R. 6 W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 38 to 42 degrees F.
Mean summer soil temperature - 42 to 46 degrees F.
Moisture control section - between 8 and 24 inches.
Volcanic glass - greater than 30 percent in the coarse silt and sand fraction of one or more horizons within 30 inches.
Surface stones or boulders - 0 to 20 percent.
A horizon - Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 1 or 2
Texture: loam or sandy loam
Clay content: 12 to 23 percent
Rock fragments: 5 to 50 percent--0 to 35 percent stones and cobbles, 5 to 30 percent gravel
Reaction: pH 5.6 to 7.3
E horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 3, 4, or 5 moist
Chroma: 1 or 2
Texture: loam or sandy loam
Clay content: 12 to 20 percent
Rock fragments: 0 to 50 percent--0 to 35 percent stones and cobbles, 0 to 30 percent gravel
Reaction: pH 5.6 to 7.3
Bw horizon - Hue: 10YR or 2.5Y
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 1 or 2
Texture: loam or sandy loam
Clay content: 12 to 18 percent
Rock fragments: 35 to 60 percent--10 to 40 percent stones and cobbles, 20 to 35 percent gravel
Reaction: pH 5.6 to 7.3
BC horizon - Hue: 10YR or 2.5Y
Value: 7 or 8 dry, 5 or 6 moist
Chroma: 1 or 2
Texture: loam, sandy loam, or loamy sand
Clay content: 5 to 15 percent
Rock fragments: 35 to 70 percent--10 to 50 percent stones and cobbles; 20 to 50 percent gravel
Reaction: pH 6.1 to 7.8
COMPETING SERIES:
Frankcreek (WA) - has a xeric moisture regime.
Hartop (WA) - has a lithic contact at 20 to 40 inches; has a xeric moisture regime.
Judco (MT) - has a paralithic contact at 50 to 60 inches.
Karloff (MT) - has a paralithic contact at 20 to 38 inches.
Koffgo (ID) - has a udic moisture regime.
Verhart (WA) - has a xeric moisture regime.
Volmont (WA) - has a xeric moisture regime.
Wellsfar (WA) - has a mparalithic contact at 20 to 40 inches; has a xeric moisture regime.
Winsand (WA) - has a xeric moisture regime.
GEOGRAPHIC SETTING:
Landform- alluvial fans and sideslopes of mountains.
Elevations - 5,500 to 8,000 feet.
Slopes - 4 to 60 percent.
Parent material - slope alluvium and colluvium from tuffaceous volcanic rocks.
Climate - long, cold winters; cool, moist springs; short, cool summers.
Mean annual precipitation - 15 to 24 inches.
Mean annual air temperature - 36 to 40 degrees F.
Frost-free period - 30 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained, moderate permeability.
USE AND VEGETATION: Torpy soils are used for timber production, understory grazing, watershed, and as wildlife habitat. The potential native vegetation is mainly lodgepole pine, Douglas-fir, grouse whortleberry, pinegrass, Oregon grape, common juniper, and white spirea.
DISTRIBUTION AND EXTENT: Torpy soils are of small extent in southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jefferson County, Montana, 1998.
REMARKS: Soil interpretive record: MT1504, MT1731, MT3037. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 8 inches (A and E horizons); a cambic horizon from 8 to 34 inches (Bw horizon); a particle-size control from 10 to 40 inches (Bw and BC horizons). Torpy soils have a cryic temperature regime and an ustic moisture regime.
The 3/2008 description reflects a change in classification from Loamy-skeletal, mixed, superactive Vitrandic Eutrocryepts to Loamy-skeletal, mixed, superactive Ustivitrandic Haplocryepts due to revision of the cryepts great groups and subgroups. The competing series section was not updated and should be reviewed after all the cryepts have been re-classified.