LOCATION BULKLEY COEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Chromic Haplusterts
TYPICAL PEDON: Bulkley silty clay loam, on a north facing, 20 percent slope in rangeland at an elevation of 6,800 feet. (Colors are for dry soil unless otherwise noted.) When described on October 11, 1978 the soil was dry throughout.
A--0 to 4 inches; dark grayish brown (10YR 4/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; hard, firm, very sticky and very plastic; common fine roots; few fine tubular pores; slightly alkaline (pH 7.4); abrupt smooth boundary. (2 to 6 inches thick)
Bss1--4 to 14 inches; brown (10YR 5/3) silty clay, brown (10YR 4/3) moist; moderate medium subangular blocky structure parting to moderate fine subangular blocky; extremely hard, firm, very sticky and very plastic; few fine roots; few fine tubular pores; many medium and coarse slickensides; slightly alkaline (pH 7.4); clear smooth boundary.
Bss2--14 to 26 inches; brown (10YR 5/3) silty clay, brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate coarse angular blocky; extremely hard, very firm, very sticky and very plastic; few fine roots; few fine tubular pores; many medium and coarse slickensides; strongly effervescent; 8 percent calcium carbonate equivalent; moderately alkaline (pH 8.0); clear smooth boundary.
Bss3--26 to 32 inches; pale brown (10YR 6/3) silty clay, brown (10YR 5/3) moist; moderate coarse prismatic structure parting to moderate coarse angular blocky; extremely hard, very firm, very sticky and very plastic; few fine roots; few fine tubular pores; common medium and coarse slickensides ; strongly effervescent; 11 percent calcium carbonate equivalent; moderately alkaline (pH 8.0); clear smooth boundary. (The combined thickness of the Bss horizon ranges from 24 to 50 inches thick)
Bk--32 to 46 inches; pale brown (10YR 6/3) silty clay, brown (10YR 5/3) moist; moderate coarse subangular blocky structure; extremely hard, very firm, very sticky and very plastic; few fine roots; few fine tubular pores; common fine and medium irregular soft seams and threads of calcium carbonate; strongly effervescent; 13 percent calcium carbonate equivalent; moderately alkaline (pH 8.4); clear smooth boundary. (4 to 20 inches thick)
Bky--46 to 65 inches; light yellowish brown (2.5Y 6/4) silty clay, light olive brown (2.5Y 5/4) moist; weak medium prismatic structure parting to weak medium subangular blocky; extremely hard, very firm, very sticky and very plastic; few fine tubular pores; common fine and medium threads of calcium carbonate and gypsum; violently effervescent; 9 percent calcium carbonate equivalent; moderately alkaline (pH 8.2). ( 0 to 21 inches thick)
TYPE LOCATION: Routt County, Colorado; about 7 miles southwest of Hayden, Colorado; located about 2,500 feet north and 1,200 feet west of the southeast corner of sec. 3, T. 5 N., R. 89 W.; Hayden, Co USGS quad; lat. 40 degrees 25 minutes 1 second N. and long. 107 degrees 21 minutes 25 seconds W., NAD 27
RANGE IN CHARACTERISTICS:
Soil moisture regime: Ustic
Mean annual soil temperature: 42 to 46 degrees F.
Mean annual summer soil temperature: 59 to 64 degrees F.
Depth to calcareous material : 0 to 35 inches
Depth to secondary calcium carbonate: 28 to 50 inches
Depth to secondary gypsum: 40 to more than 65 inches
Vertic features: cracks remain open about 100 to 150 days, are 10 to 30 mm wide, and extend from the surface to 24 or more inches deep. Slickensides are common or many and are medium or coarse in size
Particle-size control section (weighted average):
Clay content: 35 to 60 percent
A horizon:
Hue: 5Y to 10YR
Value: 4 to 7 dry, 3 to 5 moist
Chroma: 2 to 4, dry or moist
Calcium carbonate equivalent: 0 to 5 percent
Reaction: neutral to moderately alkaline
Bss horizon:
Hue: 5Y to 10YR
Value: 4 to 7 dry, 3 to 6 moist
Chroma: 2 to 4 dry or moist
Texture: CL, SIC, C
Clay content: 35 to 60 percent
Rock fragments or pararock fragments: 0 to 5 percent gravel, cobbles, or stones
Calcium carbonate equivalent: 0 to 15 percent
Reaction: neutral to moderately alkaline
Bk or Bky horizon
Hue: 5Y to 10YR
Value: 4 to 7 dry, 3 to 7 moist
Chroma: 1 through 6 dry or moist
Texture: CL, SICL, SIC, C
Clay content: 35 to 60 percent
Rock fragments or pararock fragments: 0 to 5 percent gravel, cobbles, or stones
Calcium carbonate equivalent: 5 to 15 percent
Gypsum content: 0 to 5 percent
Reaction: slightly alkaline (pH 7.8) to strongly alkaline (pH 8.6)
COMPETING SERIES: Presently the only competing series is Marias. However the following series were originally classified the same as Bulkley; Aaberg, Abor, Barkof, Bascovy, Binco, Dutton, Marvan, and Styers series.
Aaberg and Binco: have a cryic temperature regime
Abor, Barkof, Bascovy, Dutton, and Styers: have a paralithic contact
Marias and Marvin: do not have secondary calcium carbonate
GEOGRAPHIC SETTING:
Parent material: fine-textured, calcareous alluvium derived from shale.
Landform: Bulkley soils are on alluvial fans, and hills.
Slopes: 2 to 65 percent
Elevation: 6,200 to 8,300 feet
Mean annual air temperature: 40 to 45 degrees F.
Mean annual precipitation: 16 to 20 inches.
Wettest months: Precipitation is relatively evenly distributed throughout the year.
Frost-free period: 65 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Hesperus series. Hesperus soils have mollic epipedons and are on hills.
DRAINAGE AND PERMEABILITY: Well drained, very high runoff, slow or very slow permeability.
USE AND VEGETATION: These soils are used primarily for small grain production, livestock grazing, and wildlife habitat. Native vegetation is western wheatgrass, Nevada bluegrass, Sandberg bluegrass, pine needlegrass, and Alkali sagebrush.
DISTRIBUTION AND EXTENT: Northwestern Colorado. LRR E, MLRA 48A, 34. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Paonia Area, Colorado. 1976.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 6 inches. (A horizon)
Vertic features: Slickensides in the zone from 4 to 32 inches (Bss1, Bss2, and Bss3 horizons).
The typical pedon was described in Routt County, Co. and updated with additional data and information on 5/97. The classification was changed from Udorthentic Chromusterts to Chromic Udic Haplusterts.
Keys to Soil Taxonomy: 7th edition, 1996
ADDITIONAL DATA:
NSSL sample number S75C0-107-004. Calcium carbonate equivalent was determined at the project office using the calcimeter method.