LOCATION THAINCREEK MT
Tentative Series
IRD. KTS-EMM
03/2014
THAINCREEK SERIES
The Thaincreek series consists of very deep, excessively drained soils that formed in alluvium. These soils occur on stream terraces. Slopes are 1 to 6 percent. Mean annual precipitation is about 560 mm, and the mean annual temperature is about 3 degrees C.
TAXONOMIC CLASS: Sandy-skeletal, mixed Ustic Haplocryolls
TYPICAL PEDON: Thaincreek sandy loam, mixed grassland and shrubland on a 2 percent slope at an elevation of 1360 meters (Colors are for dry soil unless otherwise noted).
A1--0 to 14 cm; very dark grayish brown (10YR 3/2) sandy loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine, fine, and medium roots; few very fine and fine irregular pores; 5 percent gravel and 5 percent cobbles; slightly acid (pH 6.2); clear smooth boundary.
A2--14 to 28 cm; very dark grayish brown (10YR 3/2) very cobbly loamy sand, very dark brown (10YR 2/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine, fine, and medium roots; 25 percent gravel, 20 percent cobbles, and 10 percent stones; slightly acid (pH 6.2); gradual wavy boundary. (combined thickness of A horizons is 25 to 60 cm)
BC--28 to 64 cm; very dark grayish brown (10YR 3/2) extremely cobbly sand, very dark brown (10YR 2/2) moist; weak fine subangular blocky structure parting to single grain; loose; many very fine and fine roots, common medium and coarse roots; 30 percent gravel, 30 percent cobbles, and 10 percent stones; slightly acid (pH 6.2); gradual wavy boundary. (0 to 50 cm thick)
C--64 to 150 cm; variegated extremely cobbly sand; single grain; loose; few very fine and fine roots; 30 percent gravel, 30 percent cobbles, and 10 percent stones; slightly acid (pH 6.4). (80 to 130 cm thick)
TYPE LOCATION: Chouteau County, Montana; located 540 meters north and 242 meters east of the southwest corner of sec. 28, T. 20 N., R 9 E; Arrow Peak topographic quadrangle; UTM 12T, 0530604e., 5256884n. NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 1 to 4 degrees C.
Mollic epipedon thickness - 40 to 70 cm
A horizon
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Clay content: 5 to 15 percent
Texture: sandy loam or loamy sand
Rock fragments: 10 to 50 percent--5 to 30 percent gravel, 0 to 30 cobbles, 0 to 15 percent stones
Reaction: pH 5.8 to 6.4
BC horizon
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Clay content: 0 to 10 percent
Texture: sandy loam, loamy sand, or sand
Rock fragments: 40 to 90 percent--15 to 40 percent gravel, 10 to 40 cobbles, 0 to 30 percent stones
Reaction: pH 5.8 to 6.4
C horizon
Clay content: 0 to 10 percent
Texture: loamy sand or sand
Rock fragments: 40 to 90 percent--15 to 40 percent gravel, 10 to 40 cobbles, 0 to 30 percent stones
Reaction: pH 5.8 to 6.4
COMPETING SERIES:
Bearmouth (MT) - has pH values above 6.4 in the entire profile.
GEOGRAPHIC SETTING:
Landform - stream terraces. Elevation - 1220 to 1525 meters.
Slope - 1 to 6 percent.
Parent material - alluvium from mixed sources.
Climate - long, cold winters; moist springs; short warm summers.
Mean annual precipitation - 480 to 610 mm.
Mean annual air temperature - 1 to 4 degrees C.
Frost-free period - 50 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: excessively drained, rapid permeability.
USE AND VEGETATION: Thaincreek soils are used mainly for livestock grazing, wildlife habitat, and recreation. The vegetation is mainly grasses, forbs, and shrubs with a few scattered trees; species include: Timothy, Poa sp., Bromus sp., Carex sp., Columbia needlegrass, snowberry (common & wetsren), mountain big sagebrush, serviceberry, wild rose, Oregon grape, Potentilla sp., Erigeron sp., sticky geranium, yarrow, bergamot, Douglas-fir, quaking aspen, black cottonwood, and lodgepole pine; as well as other miscellaneous grasses and forbs.
DISTRIBUTION AND EXTENT: Thaincreek soils are of limited extent in central Montana. MLRA 43B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Chouteau County, Montana, 2014. Thaincreek series is named for a drainage on the Arrow Peak topographic quadrangle.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 64 cm (A1, A2, and BC horizons)
Particle-size control section - from 25 to 100 cm (part of the A2, BC, and part of the C horizon)
Thaincreek soils have a cryic temperature regime and an ustic moisture regime.
Taxonomic version: Eleventh Edition, 2010.
National Cooperative Soil Survey
U.S.A.