LOCATION BLACKSNAG CO

Established Series
Rev. JPP/TWH
01/2023

BLACKSNAG SERIES

The Blacksnag series consists of very deep, well drained soils that formed in slope alluvium and colluvium derived from diorite. Blacksnag soils are on mountain slopes, mesas, and structural benches. Slopes range from 2 to 30 percent. Mean annual precipitation is about 40 inches and the mean annual air temperature is about 36 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Typic Dystrocryepts

TYPICAL PEDON: Blacksnag very cobbly loam, on a southwest facing, simple, 5 percent slope in spruce-fir woodland at an elevation of 10,280 feet. (Colors are for dry soil unless otherwise noted.) Described on July 30, 1986.

A1--0 to 3 inches; brown (7.5YR 4/2) very cobbly loam, dark brown (7.5YR 3/2) moist; weak medium subangular blocky structure parting to moderate medium granular; soft, very friable, slightly sticky and slightly plastic; many very fine and fine, common medium and coarse roots; few very fine and fine pores; 25 percent gravel, 20 percent cobble, 10 percent stones; moderately acid (pH 6.0); clear wavy boundary.

A2--3 to 8 inches; brown (7.5YR 5/2) very cobbly loam, dark brown (7.5YR 3/2) moist; moderate medium subangular blocky structure parting to moderate medium granular; soft, very friable, slightly sticky and slightly plastic; many very fine, common fine, few medium and coarse roots; few very fine pores; 25 percent gravel, 20 percent cobble, 10 percent stones; slightly acid (pH 6.2); clear wavy boundary. (Combined thickness of the A horizons is 4 to 9 inches)

Bw1--8 to 16 inches; brown (7.5YR 4/4) extremely cobbly loam, dark brown (7.5YR 3/4) moist; moderate medium granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine, common fine, few medium and coarse roots; few medium pores; 30 percent gravel, 25 percent cobble, 15 percent stones; moderately acid (pH 5.6); gradual wavy boundary.

Bw2--16 to 28 inches; strong brown (7.5YR 5/6) extremely cobbly loam, dark brown (7.5YR 3/4) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, few fine, medium and coarse roots; few medium pores; 30 percent gravel, 25 percent cobble, 15 percent stones; moderately acid (pH 6.0); gradual wavy boundary.

Bw3--28 to 36 inches; strong brown (7.5YR 5/6) very cobbly sandy clay loam, dark brown (7.5YR 3/4) moist; moderate medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; few very fine, fine and medium roots; few medium pores; 25 percent gravel, 20 percent cobble, 10 percent stones; slightly acid (pH 6.2); gradual wavy boundary.

Bw4--36 to 49 inches; strong brown (7.5YR 5/6) very cobbly sandy clay loam, brown (7.5YR 4/4) moist; moderate medium and coarse angular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine, fine, and medium; few medium pores; 20 percent gravel, 20 percent cobble, 5 percent stones; slightly acid (pH 6.2); gradual wavy boundary. (Combined thickness of the Bw1, Bw2, Bw3, and Bw4 horizons is 30 to 50 inches)

Bw5--49 to 60 inches; light brown (7.5YR 6/4) very cobbly sandy clay loam, brown (7.5YR 4/4) moist; moderate medium and coarse angular blocky structure; slightly hard, friable, slightly sticky and nonplastic; few very fine and fine roots; 10 percent gravel, 25 percent cobble, 5 percent stones; slightly acid (pH 6.2).

TYPE LOCATION: Montezuma County, Colorado; about 12 miles northeast of Mancos; located about 2650 feet south and 2050 feet west of the northeast corner of Sec. 3, T. 37 N., R. 12 W.; Rampart Hills USGS quad; lat. 37 degrees 29 minutes 43 seconds N. and long. 108 degrees 09 minutes 57 seconds W., NAD 27

RANGE IN CHARACTERISTICS:(depths given are measured from the mineral soil surface)
Soil moisture regime: udic; dry in some part of the moisture control section for less than 45 cumulative days (typic udic subclass)
Mean annual soil temperature: 36 to 40 degrees F.
Mean summer soil temperature: 44 to 50 degrees F.

Particle-size control section (weighted averages):
Clay content: 20 to 30 percent
Rock fragment content: 35 to 85 percent

A horizon:
Hue: 7.5YR to 10YR
Value: 4 to 6 dry, 3 or 5 moist
Chroma: 2 or 3 dry, 2 to 4 moist
Rock fragment content: 35 to 65 percent
Reaction: moderately acid or slightly acid
Base saturation: 40 to 50 percent (estimated)

Bw horizon:
Hue: 7.5YR or 10YR
Value: 4 to 7 dry, 3 to 5 moist
Chroma: 3 to 6, dry and moist
Texture, fine earth fraction: L, SL, SCL
Rock fragment content: 35 to 85 percent
Reaction: moderately acid or slightly acid
Base saturation: 35 to 50 percent (estimated)

BC or C horizon, (if present):
Hue: 7.5YR or 10YR
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 3 or 4, dry and moist
Texture, fine earth fraction: L, SCL, SL
Rock fragment content: 35 to 85 percent
Reaction: moderately acid or slightly acid

COMPETING SERIES: These are the Afley, Bracos, Jeru, Klutch, Leighcan, and Marsell series.

Afley, Bracos, and Klutch: have a lithic contact at 20 to 40 inches.

Jeru, and Leighcan: have less than 18 percent clay in their particle-size control section.

Marsell: have hues of 5YR and redder in the Bt horizon.

GEOGRAPHIC SETTING:
Parent material: slope alluvium and colluvium derived from diorite.
Landform: mountain slopes, mesas, and structural benches.
Slopes: 2 to 30 percent
Elevation: 10,000 to 11,500 feet
Mean annual air temperature: 32 to 38 degrees F.
Mean annual precipitation: 30 to 45 inches.
Wettest months: July and August receive slightly more precipitation than other months.
Driest months: May and June receive the least precipitation however, the soils are still wet and snow often still covers much of the area.
Frost-free period: 40 to 60 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Peeler, Flygare and Foidel soils.

Peeler soils have a fine-loamy particle size control section.
Flygare and Foidel soils have mollic epipedons.

DRAINAGE AND PERMEABILITY: Well drained; low to medium runoff; moderately slow permeability.

USE AND VEGETATION: Used for timber production, livestock grazing, wildlife habitat, and recreation. Native vegetation is mainly Englemann's spruce, subalpine fir, quaking aspen, whortleberry, snowberry, nodding brome, and slender wheatgrass.

DISTRIBUTION AND EXTENT: Southwestern Colorado. LRR E, MLRA 48A. This series is of small extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES PROPOSED: Animas-Dolores Area, Colorado, 1999.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 8 inches. (A1 and A2 horizons)
Cambic horizon: The zone from 8 to 60 inches. (Bw horizons)
Dystric feature: Base saturation of less than 50 percent. (part of the Bw1, Bw2, and part of the Bw3 horizons)
Particle size control section: The zone from 10 to 40 inches. (part of the Bw1, Bw2, Bw3, and part of the Bw4 horizons)

Keys to Soil Taxonomy: Classified according to the Eighth Edition, 1998

Activity class is presumed based on general trend of other soils in the area.

National Cooperative Soil Survey
U.S.A.