LOCATION BURNSON COEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Typic Haplustalfs
TYPICAL PEDON: Burnson loam, on a west facing, simple, 2 percent slope in woodland at an elevation of 8040 feet. (Colors are for dry soil unless otherwise noted.) When described on June 10, 1996 the soil was moist from 7 to 43 inches.
Oi--0 to 1 inch; decomposed and decomposing forest litter. (0 to 3 inches thick)
A--1 to 4 inches; brown (10YR 4/3) loam, very dark grayish brown (10YR 3/2) moist; moderate medium granular structure; soft, very friable, non-sticky and non-plastic; neutral (pH 6.8); clear smooth boundary. (2 to 8 inches thick)
AB--4 to 8 inches; brown (7.5YR 4/3) clay loam, dark brown (7.5YR 3/2) moist; moderate medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; 5 percent gravel; slightly acid (pH 6.4); gradual wavy boundary. (0 to 6 inches thick)
Bt1--8 to 18 inches; reddish brown (5YR 5/4) sandy clay, dark reddish brown (5YR 4/4) moist; moderate medium prismatic structure that parts to moderate medium subangular blocky; very hard, very firm, very sticky and moderately plastic; common distinct clay films on faces of peds; organic staining along some ped faces and in some root channels; 10 percent soft sandstone gravel; slightly acid (pH 6.2); gradual irregular boundary.
Bt2--18 to 29 inches; mixed colors of reddish brown (5YR 5/4) and reddish gray (5YR 5/2) sandy clay, reddish brown (5YR 4/3) and dark reddish gray (5YR 4/2) moist, reddish brown (5YR 5/4) moist crushed; moderate coarse prismatic structure that parts to moderate fine prisms; very hard, very firm, moderately sticky and moderately plastic; common prominent clay films on faces of peds and in pores; organic staining along some ped faces and in some root channels; 13 percent soft sandstone gravel; slightly acid (pH 6.1); gradual irregular boundary. (combined thickness of the Bt horizons is 18 to 40 inches)
BC--29 to 44 inches; mixed materials of reddish brown (5YR 4/4) clay and brownish yellow (10YR 6/6) sandy clay loam, dark reddish brown (5YR 3/4) and brownish yellow (10YR 6/6) moist; massive; very hard, very firm, clay is very sticky and moderately plastic, sandy clay loam is sticky and slightly plastic; many pressure faces in the clay part; 5 percent gravel; effervescent in few fine masses of lime directly above bedrock; neutral (pH 6.8); abrupt smooth boundary. (0 to 20 inches thick)
R--44 inches; sandstone bedrock, weathered in upper inch.
TYPE LOCATION: Dolores County, Colorado; about 12 miles east of Dove Creek, Colorado; located about 1200 feet south and 1700 feet east of the northwest corner of sec. 19, T. 40 N., R. 16 W.; Doe Canyon USGS quad; lat. 37 degrees 43 minutes 00 seconds N. and long. 108 degrees 39 minutes 36 seconds W., NAD 27
RANGE IN CHARACTERISTICS: (Depths are measured from the top of the mineral soil surface)
Mean annual soil temperature: 42 to 47 degrees F.
Mean summer soil temperature: 59 to 61 degrees F.
Depth to lithic contact: 40 to 60 inches to sandstone
Thickness of the ochric epipedon: 3 to 8 inches
Particle-size control section (weighted average):
Clay content: 35 to 55 percent
A horizon:
Hue: 7.5YR or 10YR
Value: 3 or 4 dry, 2 or 3 moist
Chroma: 1 to 3 dry or moist
Texture: Loam, Clay loam
Rock fragments: Total range is 0 to 5 percent sandstone fragments. 0 to 5 percent gravel, 0 to 5 percent cobbles.
Reaction: slightly acid (pH 6.1) or neutral (pH 7.3)
Bt horizon:
Hue: 5YR or 7.5YR; variable colors are due to parent material
Value: 3 to 6 dry, 3 or 4 moist
Chroma: 3 to 6 dry or moist
Texture: Clay loam, Clay, or Sandy clay
Clay content: 32 to 55 percent
Rock fragments: Total range is 0 to 15 percent sandstone gravel
Cracks: Some pedons have cracks in the Bt in some years that are less than 5 mm wide.
Reaction: slightly acid (pH 6.1) or neutral (pH 7.3)
BC horizon (a C horizon in some pedons):
Hue: 5YR to 10YR; variable colors are due to parent material
Value: 4 to 7 dry, 3 to 5 moist
Chroma: 3 to 6 dry or moist
Texture: Clay loam, Sandy clay loam, or Clay; variable textures are due to parent material
Pressure faces: Common in the clay part of the horizon
Rock fragments: Total range is 0 to 15 percent sandstone fragments; 0 to 15 percent soft sandstone gravel, 0 to 5 percent cobbles.
Reaction: neutral (pH 6.8) or slightly alkaline (pH 7.8)
COMPETING SERIES: These are the
Burnac,
Campspass,
Echolake,
Goldbug,
Goldvale,
Larkson,
Loghill,
Siesta,
Silesca, and
Spud series.
Other soils that may be competitors when their classification is updated are the:
Bario,
Dandrea,
Fortwingate, and
McVickers series.
Bario, Goldbug, Goldvale, Larkson, and Spud soils: do not have a lithic or paralithic contact within 60 inches of the mineral surface.
Burnac soils: formed mostly in parent materials derived from basalt and have greater than 35 percent rock fragments below the particle-size control section.
Campspass: has horizons of calcium carbonate accumulation.
Dandrea, Echolake, Fortwingate, and Silesca soils: have a lithic or paralithic contact at 20 to 40 inches below the mineral surface.
Loghill soils: have accumulations of secondary calcium carbonate and have 15 to 50 percent rock fragments in the Btk and Bk horizons.
McVickers soils: have light-colored eluvial horizons with value, dry greater than 4 and value, moist greater than 3 above the argillic horizon.
Siesta soils: formed in parent materials derived from pyroclastic rocks and basalt and have cinders in the lower part of the argillic horizon .
GEOGRAPHIC SETTING:
Parent material: clayey slope alluvium over residuum derived dominantly from sandstone and shale of the Dakota and Burrow canyon formation but with some influence from eolian material.
Landform: mesas, structural benches, and hills
Slopes: 0 to 30 percent
Elevation: 7,100 to 9,000 feet
Mean annual air temperature: 41 to 45 degrees F.
Mean annual precipitation: 17 to 23 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 moist through mid June from snowmelt.
Frost-free period: 70 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Jemco,
Detra, and
Beje series. All are on mesas and hillslopes.
Jemco soils are moderately deep over sandstone bedrock.
Detra soils have thick mollic epipedons.
Beje soils are shallow over sandstone bedrock and are also on ridges.
DRAINAGE AND PERMEABILITY: Well drained, low to very high runoff, slow permeability.
USE AND VEGETATION: The major uses are commercial woodland, livestock grazing, and wildlife habitat. The native plant community is ponderosa pine with an understory of Gambel's oak, snowberry, serviceberry, Arizona fescue, western wheatgrass, and needle grasses.
DISTRIBUTION AND EXTENT: Southwestern Colorado. LRR E, MLRA 48A. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Cortez Area, Colorado, Parts of Dolores and Montezuma Counties, 1997. The type location is in the Animas-Dolores Area, Colorado.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 1 to 8 inches. (A and AB horizons) The soil is dark enough but not thick enough for a mollic epipedon.
Argillic horizon: The zone from 8 to 29 inches. (Bt horizons)
Lithic contact: Sandstone bedrock at 44 inches. (R layer)
Particle-size control section: The zone from 8 to 28 inches. (Bt1 and Bt2 horizons)
Soil Taxonomy: Series clasified according to Second Edition, 1999
ADDITIONAL DATA: Hydrometer analysis of Bt horizons done at the field lab. A nearby site sampled by NSSL, sample number S86-CO-033-001, sampled as Burnac but further study by the field party determined the need for the hydrometer analysis and a new series.