LOCATION BENTEEN MT+CO UT
Established Series
Rev. JCM/JAL
12/2022
BENTEEN SERIES
Benteen series consist of moderately deep, well drained soils formed in residuum from limestone and shale. These soils are on hills and valley sides. Slopes are 2 to 45 percent. The average annual precipitation is about 22 inches and average annual temperature is about 36 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Pachic Argicryolls
TYPICAL PEDON: Benteen loam - grassland (Colors are for dry soil unless otherwise noted.)
A1--0 to 2 inches; brown (10YR 4/3) loam, very dark grayish brown (10YR 3/2) moist; weak very thin platy structure; soft, very friable, slightly sticky, plastic; many very fine roots; neutral (pH 6.8); clear smooth boundary.
A2--2 to 4 inches; brown (10YR 4/3) loam, dark brown (10YR 3/3) moist; weak coarse prismatic structure; hard, friable, moderately sticky, moderately plastic; many very fine roots; common very fine pores; neutral (pH 6.8); clear wavy boundary. (A horizon is 3 to 8 inches thick)
Bt1--4 to 10 inches; brown (10YR 5/3) clay loam, dark brown (10YR 3/3) moist; moderate medium and coarse prismatic structure; hard, friable, moderately sticky, moderately plastic; common very fine roots and pores; few patches of faint clay films on peds; neutral (pH 7.0); gradual wavy boundary.
Bt2--10 to 17 inches; brown (10YR 5/3) clay loam, dark brown (10YR 3/3) moist; moderate medium and coarse prismatic structure; hard, friable, moderately sticky, moderately plastic; common very fine roots and pores; few patches of faint clay films on peds; neutral (pH 7.1); clear wavy boundary. (Bt horizon is 8 to 15 inches thick)
BC--17 to 22 inches; pale brown (10YR 6/3) gravelly loam, brown (10YR 5/3) moist; weak medium blocky structure; hard, friable, moderately sticky, moderately plastic; common very fine roots and pores; 15 percent flat limestone fragments; slightly alkaline (pH 7.6); clear wavy boundary.
C--22 to 29 inches; pale brown (10YR 6/3) gravelly loam, brown (10YR 5/3) moist; massive; slightly hard, friable, moderately sticky, moderately plastic; 25 percent limestone fragments; slightly effervescent in spots; slightly alkaline; clear irregular boundary.
R--29 inches; limestone.
TYPE LOCATION: Big Horn County, Montana; 550 feet west and 850 feet south of junction on main trail to Windy Point, Big Horn Mountains, 2.5 miles west of Red Spring. Unsurveyed, but located approximately in section 26, T.9S., R.31E.
RANGE IN CHARACTERISTICS: The mollic epipedon is 16 to 24 inches thick. Depth to bedrock is 20 to 40 inches. Mean annual soil temperature is 40 degrees to 44 degrees F. Average summer soil temperature is 45 degrees to 52 degrees F. The hue is 10YR or 2.5Y. The A horizon has value of 3 through 5 dry, 2 or 3 moist, and chroma of 2 or 3. The B2t horizon has value of 5 or 4 dry, and chroma usually of 3 but ranging to 4 below the mollic epipedon. In many pedons the A1 and B2t horizons are partially mixed by rodent burrowing. The B2t horizon is clay loam or silty clay loam with gravel, cobble and channery fragment content ranging from 5 to 25 percent. Its clay content ranges from 25 to 35 percent. The C horizon has value of 5 or 6 dry and 4 or 5 moist. Limestone cobbles, pebbles and channery fragments make up 20 to 40 percent of the volume. In some pedons the C horizon is weakly effervescent immediately above the shattered limestone bedrock.
COMPETING SERIES: These are the
Bachus,
Bavdark,
Clayburn,
Croydon,
Crystalbutte,
Davtone,
Decross,
Dehana,
Dranburn,
Dranyon,
Hagenbarth,
Millerlake,
Pontuge,
Senchert,
Southmount,
Poodle,
Stubbs,
Thulepah,
Vadnais, and
Winu series. The Bachus, Senchert, and Vadnais soils have less then 20 percent rock fragments in the lower part of the profile. The Bavdark, Clayburn, Crystalbutte, Davtone, Decross, Dehana, Dranburn, Millerlake, Pontuge, Southmount, and Thulepah soils are very deep. The Dranyon and Hagenbarth soils are deep or very deep. The Croyden soils are deep to a paralithic contact. The Poodle and Stubbs soils are moderately deep to a paralithic contact. The Winu soils have 2Bt horizons.
GEOGRAPHIC SETTING: Benteen soils are on sloping to steep hills and valley sides at elevations of between 7,000 and 10,000 feet. The soils formed in loamy and silty residuum weathered from hard limestone and shale of Mississippian Age. Mean annual precipitation is 20 to 24 inches; mean annual temperature is 30 degrees to 42 degrees F.; frost-free period is 55 to 65 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Adel,
Babb,
Burnette, Dumcom.
Hanson,
Tropal soils and the competing
Quietus soils. Adel, Babb, Burnette and Hanson soils lack lithic contacts within depths of 40 inches.
Duncom and Tropal soils are shallow over limestone.
DRAINAGE AND PERMEABILITY: Well-drained; moderate permeability.
USE AND VEGETATION: Used for grazing only. Native vegetation is Idaho fescue, dedges, spike fescue, mountain bromegrass.
DISTRIBUTION AND EXTENT: Big Horn Mountains in Montana and north-central Colorado. They are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Big Horn County (Big Horn Area), Montana, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the surface to 17 inches (A1, A2, Bt1, and Bt2 horizons; an argillic horizon from 4 to 17 inches (Bt1 and Bt2 horizons).
National Cooperative Soil Survey
U.S.A.