LOCATION ROCKYBUTTE WYEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Aridic Haplustalfs
TYPICAL PEDON: Rockybutte loam - on a northwest facing slope of 6 percent, in native rangeland. (Colors are for dry soil unless otherwise stated)
A--0 to 4 inches; brown (7.5YR 4/3) loam, dark brown (7.5YR 3/3) moist; weak fine granular structure; slightly hard, friable; slightly sticky, slightly plastic; common very fine and fine roots; common fine pores; 5 percent subangular scoria channers; neutral; (pH 6.8); clear smooth boundary. (2 to 8 inches thick)
Bt1--4 to 10 inches; brown (7.5YR 4/4) clay loam, dark brown (7.5YR 3/4) moist; moderate medium prismatic structure parting to moderate fine and medium angular blocky structure; slightly hard, friable; moderately sticky, moderately plastic; common distinct discontinuous dark brown (7.5YR 3/3) clay films on faces of peds and in pores; 10 percent subangular scoria channers; neutral; (pH 7.2); gradual wavy boundary. (5 to 21 inches thick)
Bt2--10 to 16 inches; brown (7.5YR 4/4) channery clay loam, dark brown (7.5YR 3/4) moist; moderate medium prismatic structure parting to moderate fine and medium subangular blocky; slightly hard, very friable; moderately sticky, moderately plastic; common distinct discontinuous dark brown (7.5YR 3/3) clay films on faces of peds and in pores; 20 percent subangular scoria channers; slightly alkaline; (pH 7.4); clear wavy boundary. (0 to 12 inches thick)
Btk--16 to 23 inches; brown (7.5YR 5/4) very channery clay loam, brown (7.5YR 4/4) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable; common distinct discontinuous dark brown (7.5YR 3/3) clay films on faces of peds and in pores; few fine irregular light gray (10YR 7/2) carbonate threads throughout; 35 percent subangular scoria channers; strongly effervescent; moderately alkaline; (pH 8.0); gradual wavy boundary. (0 to 8 inches thick)
Bk--23 to 29 inches; brown (7.5YR 5/4) extremely channery loam, brown (7.5YR 4/4) moist; weak fine and medium subangular blocky structure; soft, very friable; few distinct discontinuous light gray (10YR 7/2) carbonate coats on bottom surfaces of rock fragments; few fine irregular light gray (10YR 7/2) carbonate threads throughout; 60 percent subangular scoria channers; strongly effervescent; moderately alkaline; (pH 8.2); clear wavy boundary. (6 to 17 inches thick)
2C--29 to 60 inches; fractured porcelanite with 7 percent sandy loam filling interstices and voids brown (7.5YR 5/4) sandy loam, brown (7.5YR 4/4) moist; massive; few distinct discontinuous light gray (10YR 7/2) carbonate coats on bottom surfaces of rock fragments; 65 percent subangular scoria channers and 20 percent subangular scoria flagstones and 8 percent subrounded stones; slightly effervescent but variable; few segregated masses or threads of calcium carbonates throughout; slightly alkaline.
TYPE LOCATION: Campbell County, Wyoming; about 2500 feet west and 500 feet south of the northeast corner of Sec. 18, T 56 N, R 71 W.; USGS Rocky Butte SW., WY topographic quadrangle; lat. 44 degrees 55 minutes 13 seconds N. and long. 105 degrees 26 minutes 25 seconds W.
RANGE IN CHARACTERISTICS: Depth to the base of the argillic horizon ranges from 16 to 31 inches. Depth to continuous accumulations of calcium carbonate ranges from 15 to 31 inches. The depth to fragmental material is 20 to 40 inches.
A horizon:
Hue: 10YR, 7.5YR or 5YR
Value: 4 to 6, 3 or 4 moist
Chroma: 3 or 4
Texture: very fine sandy loam, fine sandy loam or loam
Clay content: 10 to 20 percent
Reaction: neutral or slightly alkaline
Rock fragments: 0 to 14 percent
Bt horizon:
Hue: 7.5YR or 5YR
Value: 4 to 6, 3 or 4 moist
Chroma: 3 to 6
Textures: loam, clay loam or sandy clay loam
Clay content: 20 to 35 percent
Reaction: neutral or slightly alkaline
Rock fragments: 0 to 14 percent in the upper part and 15 to 50 percent in the lower part
Btk horizon:
Hue: 5YR or 7.5YR
Value: 4 to 6, 3 to 5 moist
Chroma: 3 to 6
Textures: loam, clay loam or sandy clay loam
Clay content: 20 to 35 percent
Reaction: slightly alkaline or moderately alkaline
Rock fragments: 15 to 50 percent channers
Calcium carbonate equivalence: 3 to 12 percent
Bk horizon:
Hue: 5YR or 7.5YR
Value: 4 to 6, 3 to 5 moist
Chroma 3 to 6
Textures: loam, very fine sandy loam or sandy loam
Clay content: 10 to 25 percent
Rock fragments: 35 to 75 percent channers, 0 to 5 percent flagstones
Calcium carbonate equivalence: 3 to 14 percent
2C horizon:
Hue: 2.5YR, 5YR or 7.5YR
Value: 4 to 6, 3 to 5 moist
Chroma: 3 to 6
Texture: fractured porcelanite with less than 10 percent of interstices or voids filled with loam, sandy loam or loamy sand
Rock fragments: 70 to 95 percent are channers, 0 to 15 percent flagstones, and 0 to 5 percent stones
Reaction: neutral or slightly alkaline.
COMPETING SERIES: These are the
Arnor,
Arwite,
Celavar,
Dalhart,
Deekay,
Elwop,
Evpark,
Flugle,
Fort Collins,
Gateson,
Iwela,
Oldwolf,
Olnest,
Orlie,
Parkelei,
Rauzi,
Stoneham,
Toluca and
Wagonhound series. None of these series have fragmental material at depths of less than 40 inches.
GEOGRAPHIC SETTING: Rockybutte soils are on lower sideslopes of structural fans and terraces and board summits of ridges and plateaus. They formed in alluvium or eolian deposits over weathered porcelanite or very channery slopewash derived from porcelanite. Slope ranges from 0 to 15 percent. Elevations ranges from 3,800 to 5,300 feet. The mean annual precipitation ranges from 15 to 17 inches, half of which falls as rain and snow from late March through June. The mean annual air temperature ranges from 46 to 50 degrees F. The frost-free season is about 105 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Deekay, Ironbutte, Moorhead and Muleherder soils. Deekay and Moorhead soils are are on similar position on the landscape as Rockybutte soil. They do not have fragmental material at depths of less than 40 inches. In addition, Moorhead soils are fine. Ironbutte soils are on narrow summits and ridges. They do not have argillic horizons and are shallow to fragmental material consisting of porcelanite. Muleherder soils are on sideslopes. They do not have argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; runoff is negligible to medium depending on slope; moderate over rapid permeability.
USE AND VEGETATION: These soils are utilized for rangeland and wildlife habitat. The native vegetation is mainly western wheatgrass, needleandthread, blue grama and green needlegrass.
DISTRIBUTION AND EXTENT: Rockybutte soils occur in northeast Wyoming. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado.
SERIES ESTABLISHED: Campbell County, Wyoming, Southern Part; 2001.
REMARKS: Diagnostic horizons and features recognized in this pedon are: Ochric epipedon - the zone from the surface of the soil to a depth of 4 inches (A horizon); Argillic horizon and particle size control section - the zone from 4 to 23 inches (Bt1, 2Bt2 and 2Btk horizons).
MLRR- G
Previously the Rockybutte series was correlated as a moist phase of the Teckla series.