LOCATION REDROCK COTentative Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Aridic Calciustepts
TYPICAL PEDON: Redrock clay loam, on a southwest-facing 3 percent slope under irrigated pasture at an elevation of 7015 feet. (Colors are for dry soil unless otherwise noted.)
A--0 to 3 inches; light brownish gray (10YR 6/2) clay loam, dark grayish brown (10YR 4/2) moist; moderate fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; slightly effervescent; moderately alkaline (pH 8.0); gradual smooth boundary. (2 to 6 inches thick)
Bw--3 to 10 inches; light brown (7.5YR 6/3) clay loam, brown (7.5YR 4/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, very friable, slightly sticky and slightly plastic; slightly effervescent; moderately alkaline (pH 8.0); gradual smooth boundary. (7 to 10 inches thick)
Bk1--10 to 30 inches; pinkish white (7.5YR 8/2) clay loam, pinkish gray (7.5YR 6/2) moist; massive; hard, friable, slightly sticky and slightly plastic; 3 percent pebbles, 2 percent cobbles; many visible secondary calcium carbonate occurring as finely divided marl-like forms; strongly effervescent; moderately alkaline (pH 8.4); gradual smooth boundary.
Bk2--30 to 60 inches; pinkish gray (7.5YR 7/2) clay loam, brown (7.5YR 5/2) moist; massive; very hard, friable, slightly sticky and slightly plastic; 5 percent pebbles; common visible secondary calcium carbonate occurring as concretions and in thin seams and streaks; strongly effervescent; moderately alkaline (pH 8.2). (Combined thickness of the Bk horizons is 48 to 54 inches.)
TYPE LOCATION: Montrose County, Colorado; located about 1320 feet east and 400 feet north of the center of section 15, T. 49N., R. 8 W.; USGS Red Rock Canyon topographic quadrangle; latitude 38 degrees, 30 minutes, 47 seconds north and longitude 107 degrees, 45 minutes, 09 seconds west.
RANGE IN CHARACTERISTICS:
Soil moisture: The soil moisture regime is ustic bordering on aridic.
Mean annual soil temperature: 44 to 46 degrees F.
Mean summer soil temperature: 55 to 57 degrees F.
Depth to cambic: 2 to 6 inches
Depth to calcic: 9 to 16 inches
Particle-size control section (weighted average): 28 to 35 percent clay with 0 to 10 percent rock fragments
A horizon:
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2 or 3 dry or moist
Texture: loam or clay loam with 22 to 32 percent clay
Rock fragments: 0 to 15 percent
Reaction: moderately alkaline or strongly alkaline
Bw horizon:
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 or 4 dry or moist
Texture: loam or clay loam with 22 to 32 percent clay
Rock fragments: 0 to 10 percent
Reaction: moderately alkaline or strongly alkaline
Bk horizon:
Hue: 7.5YR or 10YR
Value: 6 through 8 dry, 4 through 6 moist
Chroma: 2 or 3 dry or moist
Texture: loam or clay loam with 25 to 34 percent clay
Rock fragments: 0 to 15 percent
Calcium carbonate equivalent: 15 to 30 percent
Reaction: moderately alkaline or strongly alkaline
COMPETING SERIES: Whitesage series. Whitesage soils have less that 28 percent clay in the particle-size control section.
GEOGRAPHIC SETTING:
Parent material: alluvium from mixed sedimentary sources
Landform: alluvial fans and valley side slopes
Slope: 2 to 10 percent
Elevation: 6,800 to 7,800 feet
Mean annual precipitation: 13 to 16 inches
Mean annual temperature: 42 to 44 degrees F.
Frost-free period: 90 to 100 days
GEOGRAPHICALLY ASSOCIATED SOILS: There are the Blanyon and Bostwick soils. Blanyon soils have a fine-textured argillic horizon and do not have a calcic horizon. The Bostwick soils have a mollic epipedon, an argillic horizon, and do not have a calcic horizon.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderately slow permeability.
USE AND VEGETATION: This soil is used for irrigated hay and pasture, rangeland, and wildlife habitat. Native vegetation is western wheatgrass, muttongrass, Wyoming big sagebrush, and black sagebrush.
DISTRIBUTION AND EXTENT: Southwestern Colorado. The series is of minor extent. MLRA 48A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Montrose County, Colorado, Ridgway Soil Survey Area, 1994. The name is taken from a canyon and a USGS topographical quadrangle name.
REMARKS: Diagnostic horizons and features recognized in this pedon include an ochric horizon from 0 to 3 inches, a cambic horizon from 3 to 10 inches, and a calcic horizon from 10 to 60 inches.
The classification was changed from Haplocalcidic Ustochrepts to Aridic Calciustepts 1/99.
Taxonomic version: Eighth Edition, 1998.