LOCATION ELKHEAD COTentative Series
TAXONOMIC CLASS: Fine, smectitic Vertic Haplocryolls
TYPICAL PEDON: Elkhead clay loam, on a nearly level slope in hay meadow at an elevation of 6,600 feet. (Colors are for dry soil unless otherwise noted.) When described on July 11, 1984 the soil was moist from 16 to 38 inches and saturated below 38 inches.
A--0 to 18 inches; very dark grayish brown (10YR 3/2) clay loam, black (10YR 2/1) moist; moderate fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few medium, common fine roots; few very fine tubular pores; thin layers of yellowish brown (10YR 5/4) loamy fine sand 1/16 to 1 inch thick; neutral (pH 7.2); clear smooth boundary. (16 to 40 inches thick)
Bw--18 to 38 inches; dark brown (10YR 3/3) clay, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; very hard, very firm, moderately sticky and moderately plastic; few fine roots; few fine tubular pores; common faint discontinuous pressure faces on faces of peds; few faint patchy very dark gray (10YR 3/1) moist, organic stains on faces of peds in upper part of horizon; neutral (pH 7.2); gradual smooth boundary. (0 to 22 inches thick)
Bk1--38 to 50 inches; dark grayish brown (10YR 4/2) clay, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; very hard, very firm, moderately sticky and moderately plastic; few fine roots, few fine tubular pores; common fine seams of calcium carbonate and common fine calcium carbonate threads on faces of peds; slightly effervescent; 20 percent calcium carbonate equivalent; few fine faint brown (10YR 4/3) moist, masses of iron accumulation; moderately alkaline (pH 8.2); gradual smooth boundary.
Bk2--50 to 75 inches; yellowish brown (10YR 5/4) clay, olive brown (2.5Y 4/4) moist; weak coarse subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine roots; few fine tubular pores; common fine seams of calcium carbonate on faces of peds; strongly effervescent; 20 percent calcium carbonate equivalent; common fine distinct yellowish brown (10YR 5/4) moist, masses of iron accumulation; moderately alkaline (pH 8.4). (Total thickness of the Bk horizon is 35 to 59 inches thick)
TYPE LOCATION: Routt County, Colorado; about 5 miles east of Milner; located about 2,300 feet east and 2,100 feet north of the southwest corner of sec. 9, T. 6 N., R. 85 W.; Cow Creek USGS quad; lat. 40 degrees 29 minutes 28 seconds N. and long. 106 degrees 55 minutes 40 seconds W., NAD 27
RANGE IN CHARACTERISTICS:
Soil moisture regime: ustic. However, it occurs on a flood plain and receives additional moisture from endosaturation.
Mean annual soil temperature: 39 to 44 degrees F.
Mean annual summer soil temperature: 45 to 50 degrees F.
Thickness of the mollic epipedon: 24 to 55 inches
Linear extensibility (estimated): 6.0 to 8.0 cm
Depth to calcic horizon: 20 to 40 inches
Depth to redox concentrations: 30 to 40 inches to masses of iron accumulation
Water table: depth is 2.5 to 3.5 feet, kind is apparent, months are April to June and usually 3.5 feet to 5 feet the remainder of the year.
Particle-size control section (weighted average):
Clay content: 35 to 45 percent
A horizon:
Value: 2 to 4 dry, 2 or 3 moist
Chroma: 1 to 3 dry or moist
Reaction: neutral or slightly alkaline
Bw horizon:
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 2 or 3 dry or moist
Texture: SICL, CL, SIC, C
Clay content: 35 to 45 percent
Reaction: neutral or slightly alkaline
Bk horizon:
Hue: 10YR to 5Y
Value: 4 to 7 dry, 3 to 6 moist
Chroma: 2 to 6 dry or moist
Texture: SICL, CL, SIC, C
Clay content: 35 to 45 percent
Calcium carbonate equivalent: 15 to 40 percent
Reaction: slightly alkaline or moderately alkaline
COMPETING SERIES: There are no competing series. The series in a closely related family are Chubbflat, Clover Springs, and Polich. Chubbflat, Clover Springs, and Polich have fine-silty particle-size control sections.
GEOGRAPHIC SETTING:
Parent material: alluvium derived from shale.
Landform: flood plains.
Slopes: 0 to 3 percent
Elevation: 6,500 to 8,000 feet
Mean annual air temperature: 37 to 40 degrees F.
Mean annual precipitation: 18 to 25 inches.
Wettest months: Precipitation is relatively evenly distributed throughout the year.
Frost-free period: 35 to 55 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cochetopa, Clayburn, and Matmore (T) series. Cochetopa and Clayburn soils are well drained soils that occur on hillslopes and elevated areas. Matmore soils occur on lower flood plains and are somewhat poorly drained.
DRAINAGE AND PERMEABILITY: Moderately well drained, high runoff, slow permeability. These soils are rarely flooded for brief periods during the months of April to June.
USE AND VEGETATION: These soils are used for irrigated hay and pasture or are in native range and are used for livestock grazing or wildlife habitat. The native plant community is basin wildrye, western wheatgrass, Columbia needlegrass, and streambank wheatgrass.
DISTRIBUTION AND EXTENT: North central Colorado. LRR E, MLRA 48A. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Routt County, Colorado. 1997. The name comes from a creek in Routt County.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: The zone from 0 to 55 inches. (A, Bw, and Bk1 horizons)
Cumulic feature: An irregular decrease in organic carbon inferred from the fine stratification observed from 0 to 18 inches (A horizon)
Calcic horizon: The zone from 38 to 75 inches. (Bk1 and Bk2 horizons)
Redoximorphic features: Masses of iron accumulation from 38 to 75 inches (Bk1 and Bk2 horizons).
Endosaturation: an observed saturated zone below 38 inches (Bk1 and Bk2 horizons).
Keys to Soil Taxonomy: Seventh Edition, 1996.
ADDITIONAL DATA: The suborder would be Cumulic Oxyaquic if such a placement were available in soil taxonomy. Calcium carbonate equivalent was determined at the project office using the calcimeter method.