LOCATION LAKEBENCH CO+UTEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Aridic Calciustepts
TYPICAL PEDON: Lakebench silt loam, on a north facing, convex, 4 percent slope in pinyon pine and juniper at an elevation of 6,630 feet. (Colors are for dry soil unless otherwise noted.) When described on April 6, 1994 the soil was moist from 0 to 27 inches. The surface is covered by 5 percent gravel.
A--0 to 3 inches; brown (7.5YR 4/4) silt loam, dark brown (7.5YR 3/3) moist; moderate fine and medium granular structure; soft, friable, slightly sticky and slightly plastic; many very fine and fine roots; few very fine tubular pores; 5 percent gravel; strongly effervescent; 6 percent calcium carbonate equivalent; calcium carbonate disseminated; slightly alkaline (pH 7.7); clear smooth boundary. (3 to 5 inches thick)
Bk1--3 to 9 inches; brown (7.5YR 5/4) loam, brown (7.5YR 4/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine, common coarse roots; few very fine tubular pores; common fine irregular calcium carbonate threads throughout; violently effervescent; 21 percent calcium carbonate equivalent; slightly alkaline (pH 7.7); abrupt smooth boundary. (Combined thickness of the Bk horizon is 30 to 60 or more inches thick)
Bk2--9 to 25 inches; pinkish white (7.5YR 8/2) loam, pink (7.5YR 7/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; few very fine tubular pores; many coarse and very coarse irregular soft calcium carbonate masses throughout; violently effervescent; 40 percent calcium carbonate equivalent; moderately alkaline (pH 8.1); gradual wavy boundary.
Bk3--25 to 35 inches; pink (7.5YR 7/3) loam, light reddish brown (5YR 6/4) moist; weak fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine and medium roots; few very fine tubular pores; many fine and medium irregular soft calcium carbonate masses throughout; violently effervescent; 24 percent calcium carbonate equivalent; moderately alkaline (pH 7.9); gradual smooth boundary.
Bk4--35 to 45 inches; light reddish brown (5YR 6/3) loam, reddish brown (5YR 5/4) moist; weak fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine and medium roots; few very fine tubular pores; many fine and medium irregular soft calcium carbonate masses throughout; violently effervescent; 24 percent calcium carbonate equivalent; moderately alkaline (pH 8.1); gradual smooth boundary.
Bk5--45 to 50 inches; reddish brown (5YR 5/3) gravelly loam, reddish brown (5YR 4/4) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine and medium roots; few very fine tubular pores; 20 percent gravel; many fine irregular soft calcium carbonate masses throughout; violently effervescent; 21 percent calcium carbonate equivalent; moderately alkaline (pH 8.1); gradual wavy boundary.
Bk6--50 to 60 inches; light reddish brown (5YR 6/4) loam, reddish brown (5YR 5/4) moist; weak fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few fine and medium roots; few very fine tubular pores; many fine irregular soft calcium carbonate masses throughout; violently effervescent; 21 percent calcium carbonate equivalent; moderately alkaline (pH 8.1).
TYPE LOCATION: Moffat County, Colorado; 100 feet east and 1,350 feet south of the northwest corner of section 24, T. 6 N., R. 100 W.; USGS Haystack Rock topographical quadrangle; lat. 40 degrees 26 minutes 45 seconds N. and long. 108 degrees 34 minutes 45 seconds W., NAD 27.
RANGE IN CHARACTERISTICS:
Soil moisture: The soil moisture control section is affected by precipitation that falls evenly throughout the year with the exception of peaks in the spring, late summer and early fall. Ustic moisture regime bordering on Aridic.
Mean annual soil temperature: 40 to 46 degrees F.
Mean annual summer soil temperature: 62 to 68 degrees F.
Surface rock fragments: 0 to 35 percent sandstone, basalt and/or limestone gravel. 0 to 5 percent sandstone, basalt and/or limestone cobbles or channers. 0 to 5 percent basalt stones
Depth to calcic horizon: 3 to 30 inches
Thickness of the calcic horizon: 30 to 60 inches or more
Particle-size control section:
Clay content: 12 to 30 percent total clay with 0 to 18 percent non-carbonate clay
Rock fragments: 0 to 25 percent sandstone rock fragments
A horizon:
Hue: 5YR or 7.5YR
Value: 3 to 6 dry, 2 to 4 moist
Chroma: 2 to 5, dry or moist
Rock fragments: 0 to 35 percent sandstone, basalt or limestone gravel or cobbles, with a few pedons having 0 to 5 percent basalt stones
Calcium carbonate equivalent: 0 to 15 percent
Reaction: neutral to moderately alkaline
Bw horizon (when present):
Hue: 5YR or 7.5YR
Value: 3 to 6, dry or moist
Chroma: 3 to 6, dry or moist
Texture: fine sandy loam or loam
Rock fragments: 0 to 15 percent sandstone, basalt or limestone gravel and cobbles
Calcium carbonate equivalent: 0 to 10 percent
Reaction: neutral to moderately alkaline
Bk or Ck horizon:
Hue: 5YR or 7.5YR
Value: 4 to 8 dry, 4 to 7 moist
Chroma: 2 to 6, dry or moist
Texture: fine sandy loam, silt loam, sandy clay loam, loam, gravelly loam, gravelly fine sandy loam, gravelly sandy clay loam, cobbly fine sandy loam, or clay loam
Rock fragments: 0 to 35 percent sandstone, basalt or limestone gravel and cobbles, with a few pedons having 0 to 5 percent basalt stones
Calcium carbonate equivalent: 5 to 40 percent
Reaction: slightly alkaline to strongly alkaline
COMPETING SERIES: These are Amesha, Kalsted and Redbull soils. Amesha and Kalsted soils have hues of 10YR or yellower. Redbull soils are deep, with a paralithic contact between 40 and 60 inches.
GEOGRAPHIC SETTING:
Parent material: alluvium, residuum and eolian deposits derived from mixed sources.
Landform: structural benches, alluvial fans, mesas, cuestas and fan remnants.
Slopes: 3 to 30 percent
Elevation: 6,000 to 7,150 feet
Mean annual air temperature: 38 to 45 degrees F.
Mean annual precipitation: 12 to 16 inches; precipitation is relatively evenly distributed throughout the year with the exception of peaks in the spring, late summer and early fall.
Frost-free period: 75 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Cragnot,
Grapit,
Pensore, and
Strell series.
Cragnot, Grapit, and Pensore: loamy-skeletal.
Pensore and Strell: bedrock less than 20 inches deep.
DRAINAGE AND PERMEABILITY: well drained, very low to medium runoff, moderately rapid permeability.
USE AND VEGETATION: Livestock grazing and wildlife habitat. Native vegetation is needleandthread, scarlet globemallow, Sandberg bluegrass, Wyoming big sagebrush, and western wheatgrass.
DISTRIBUTION AND EXTENT: Northwestern Colorado and northeastern and central Utah. LRR D, MLRA 34, 35 and 47. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Moffat County (Dinosaur National Monument), Colorado. 1997. (The name is taken from a geographic location in the Dinosaur National Monument).
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 3 inches. (A horizon)
Calcic horizon: The zone from 3 to 60 inches. (Bk horizons)
ADDITIONAL DATA: Percent calcium carbonate determined by calcimeter. Activity class is estimated.
The classification was changed from Haplocalcidic Ustochrepts to frigid Aridic Calciustepts 12/98.
Keys to Soil Taxonomy: Eighth Edition, 1998