LOCATION BASCOVY MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Aridic Leptic Haplusterts
TYPICAL PEDON: Bascovy clay, grassland. (Colors are for dry soil unless otherwise noted)
A1--0 to 1/4 inch; light brownish gray (2.5Y 6/2) clay, grayish brown (2.5Y 5/2) moist, vesicular crust; hard, firm, very sticky and very plastic; common uncoated sand grains on the surface; slightly effervescent; slightly alkaline (pH 7.9); abrupt smooth boundary. (0 to 1/2 inch thick)
A2--1/4 to 6 inches; grayish brown (2.5Y 5/2) clay; dark grayish brown (2.5Y 4/2) moist; moderate medium and fine subangular blocky structure; extremely hard, firm, very sticky and very plastic; common fine and medium roots; few fine pores; few vertical cracks less than 1/2 inch wide; slightly effervescent in spots; moderately alkaline; clear smooth boundary. (2 to 8 inches thick)
Bss--6 to 10 inches; olive gray (5Y 5/2) clay, olive gray (5Y 4/2) moist; moderate medium and fine subangular blocky structure; extremely hard, very firm, very sticky and very plastic; few fine roots; few fine pores; few vertical cracks less than 1/4 inch wide; common faint slickensides or pressure faces; slightly alkaline (pH 7.6); gradual smooth boundary. (0 to 24 inches thick)
Bssy--10 to 15 inches; olive gray (5Y 5/2) clay, olive gray (5Y 5/2) moist; moderate medium and fine subangular blocky structure; extremely hard, very firm, very sticky and very plastic; few fine roots; few fine pores; common distinct slickensides; few fine threads of gypsum; neutral (pH 6.8); gradual wavy boundary. (5 to 13 inches thick)
BC--15 to 23 inches; olive gray (5Y 5/2) clay, olive gray (5Y 4/2) moist; weak medium and fine subangular blocky structure; extremely hard, very firm, very sticky and very plastic, few fine pores; 15 percent hard shale chips; moderately acid (pH 5.6); gradual wavy boundary. (0 to 6 inches thick)
Cr--23 to 60 inches; olive gray and olive brown semiconsolidated shale.
TYPE LOCATION: Blaine County, Montana; about 2,340 feet north and 150 feet west of the SE corner of sec. 17, T. 25 N., R. 21 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Depth to Cr horizon - 20 to 40 inches.
A Bw horizon is allowed.
The chroma of 1 is lithochromic.
A horizons - Hue: 10YR, 2.5Y, or 5Y
Value: 5, 6, or 7 dry; 3, 4, or 5 moist
Chroma: 1, 2, or 3
Texture: clay, silty clay, clay loam, or silty clay loam
Clay content: 35 to 60 percent
EC: 0 to 4 mmhos/cm
Reaction: pH 6.6 to 8.4
Bss horizon - Hue: 10YR, 2.5Y, or 5Y
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 1, 2, or 3
Texture: clay or silty clay
Clay content: 40 to 60 percent
EC: 0 to 4 mmhos/cm
Reaction: pH 6.1 to 8.4
Bssy horizon - Hue: 10YR, 2.5Y, or 5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 1, 2, or 3
Texture: clay or silty clay
Clay content: 40 to 60 percent
Gypsum: 1 to 5 percent
EC: 0 to 4 mmhos/cm
Reaction: 6.1 to 8.4
By, BC, or C horizon - Hue: 10YR, 2.5Y, or 5Y
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 1 or 2
Texture: clay or silty clay
Clay content: 40 to 60
EC: 0 to 8 mmhos/cm
Reaction: 5.1 to 8.4
Some pedons have a By or C horizon.
COMPETING SERIES: As currently and previously (Udorthentic Chromusterts) classified. Reclassification of the outdated Chromusterts may affect this list of series.
Aaberg (CO) - does not have a horizon of gypsum accumulations.
Abor (MT) - has a horizon of lime accumulation.
Barkof (MT) - does not have a horizon of gypsum accumulation; has precipitation less than 15 inches.
Binco (CO) - does not have a paralithic contact above a depth of 40 inches.
Bulkley (CO) - does not have a paralithic contact above a depth of 40 inches.
Styers (T)(CO) - has hues of 7.5YR and redder in the control section.
GEOGRAPHIC SETTING:
Landform - sedimentary plains; hills; alluvial fans; strath terraces.
Elevation - 2,400 to 3,800 feet.
Slope- 0 to 45 percent.
Parent material - material weathered from semiconsolidated shale and mudstone.
Climate - cold, dry winters; warm summers.
Mean annual precipitation - 10 to 14 inches.
Mean annual air temperature - 40 to 45 degrees F.
Frost-free period - 100 to 130 days.
DRAINAGE AND PERMEABILITY: Well drained. Very slow permeability. Runoff is medium to very high depending on slopes.
USE AND VEGETATION: Bascovy soils are used for range; some areas are used for dryland cropland. Potential native vegetation is western wheatgrass, prairie junegrass, blue grama, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Bascovy soils are of moderate extent in central and eastern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Blaine County, Montana, 1976.
REMARKS: Soil interpretations record: MT0281.
Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface of the soil to a depth of 7 inches (A1, A2, and part of Bss horizons); slickensides - from 6 to 15 inches (Bss and Bssy horizons); transition horizon - the zone from 15 to 23 inches (BC horizon); and a paralithic contact - at a depth of 23 inches. Bascovy soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.