LOCATION DUNLAP MT
Established Series
Rev. KTS-RJS
01/2012
DUNLAP SERIES
The Dunlap series consists of shallow, well drained soils that formed in residuum derived from weakly consolidated, coarse grained sandstone. These soils occur on low hills. Slopes are 2 to 15 percent. Mean annual precipitation is about 230 mm, and the mean annual air temperature is about 5 degrees C.
TAXONOMIC CLASS: Loamy, mixed, superactive, frigid, shallow Aridic Haplustalfs
TYPICAL PEDON: Dunlap sandy loam, in rangeland on a 6 percent slope at an elevation of 1882 meters (colors are for dry soil unless otherwise noted).
A--0 to 10 cm; grayish brown (10YR 5/2) sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine roots throughout; common very fine and fine irregular pores throughout; 10 percent gravel; neutral (pH 6.8); clear smooth boundary. (8 to 15 cm thick)
Bt1--10 to 28 cm; brown (10YR 5/3) gravelly sandy clay loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine and fine roots throughout; common very fine irregular pores throughout; 40 percent distinct patchy clay films on faces of peds; 18 percent gravel; neutral (pH 6.8); gradual wavy boundary.
Bt2--28 to 41 cm; brown (10YR 5/3) gravelly sandy clay loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots throughout; few very fine irregular pores throughout; 40 percent faint patchy clay films on faces of peds; 22 percent gravel; neutral (pH 7.0); gradual wavy boundary. (Combined thickness of Bt horizons - 20 to 38 cm)
Cr--41 to 64 cm; highly weathered sandstone that crushes to a gravelly sand. (15 to 50 cm thick)
R--64 to 152 cm; hard sandstone bedrock.
TYPE LOCATION: Beaverhead County, Montana; located about 2360 feet south and 1150 feet east of the northwest corner of sec. 22, T. 9 S., R 13 W; Bachelor Mountain topographic quadrangle; UTM 12T, 327680e., 4989628n. NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 5 to 8 degrees C.
Depth to top of argillic horizon - 8 to 15 cm
Depth to paralithic contact - 25 to 50 cm
Depth to lithic contact - 50 to 100 cm
A horizon
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3; dry or moist
Clay content: 15 to 20 percent
Rock fragments: 10 to 30 percent gravel
Reaction: pH 6.6 to 7.3
Bt horizons
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 to 4; dry or moist
Clay content: 20 to 35 percent
Rock fragments: 10 to 30 percent gravel
Reaction: pH 6.6 to 7.3
COMPETING SERIES:
Gateridge (WY) - does not have a lithic contact below the paralithic contact
GEOGRAPHIC SETTING:
Landform - low hills
Elevation - 1830 to 1920 meters
Slope - 2 to 15 percent
Parent material - residuum derived from weakly consolidated, coarse grained sandstone
Climate - long, cold winters; moist springs; warm summers
Mean annual precipitation - 225 to 355 mm
Mean annual air temperature - 4 to 7 degrees C.
Frost-free period - 70 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Dunlap soils are used mainly for rangeland. The vegetation is mainly Wyoming big sagebrush, bluebunch wheatgrass, sandberg bluegrass, Indian ricegrass, needleandthread, and miscellaneous forbs.
DISTRIBUTION AND EXTENT: Dunlap soils are of small extent in southwestern Montana. MLRA - 44B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Horse Prairie-South Valley Area - Part of Beaverhead County, Montana, 2011; proposed in Beaverhead County, Montana, 2008.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - from 0 to 10 cm (A horizon)
Argillic horizon - from 10 to 41 cm (Bt1, Bt2 horizons)
Paralithic contact - from 41 to 64 cm (Cr horizon)
Lithic contact - at 64 cm (R horizon)
Particle-size control section - from 10 to 41 cm (Bt1, Bt2 horizons)
Dunlap soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.
Taxonomic version: Eleventh Edition, 2010
National Cooperative Soil Survey
U.S.A.