LOCATION SPONSOR COEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Typic Argicryolls
TYPICAL PEDON: Sponsor loam, on a west facing, simple, 15 percent slope in aspen-fir woodland at an elevation of 9,000 feet. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 1 inch; organic layer of leaves, roots and twigs. (1 to 3 inches thick)
A1--1 to 7 inches; dark reddish gray (5YR 4/2) loam, dark reddish brown (5YR 2/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; moderately acid (pH 6.0); clear smooth boundary. (5 to 12 inches thick)
A2--7 to 12 inches; dark reddish gray (5YR 4/2) loam, dark reddish brown (5YR 2/2) moist; weak, medium subangular blocky structure parting to weak medium granular structure; slightly hard, very friable, slightly sticky and slightly plastic; slightly acid (pH 6.2); clear smooth boundary. (0 to 11 inches thick)
Bt1--12 to 25 inches; reddish brown (5YR 5/3) cobbly clay loam, dark reddish gray (5YR 4/2) moist; moderate medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common distinct clay films on faces of peds; 5 percent gravel, 10 percent cobble; slightly acid (pH 6.2); gradual smooth boundary. (12 to 30 inches thick)
Bt2--25 to 43 inches; reddish brown (5YR 5/3) cobbly clay loam, dark reddish gray (5YR 4/2) moist; moderate medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common distinct clay films on faces of peds; 5 percent gravel, 20 percent cobble, 5 percent stone; slightly acid (pH 6.4); gradual smooth boundary. (12 to 24 inches thick)
Bt3--43 to 61 inches; reddish brown (5YR 5/3) very stony clay loam, dark reddish gray (5YR 4/2) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few faint clay films on faces of peds; 5 percent gravel, 20 percent cobble, 25 percent stone; neutral (pH 6.6).
TYPE LOCATION: La Plata County, Colorado; about 2 miles east of Vallecito Reservoir; located about 2,500 feet south and 1,500 feet east of the northwest corner of sec. 22, T. 37 N., R. 6 W.; Vallecito Reservoir USGS quad; lat. 37 degrees 27 minutes 34 seconds N. and long. 107 degrees 31 minutes 33 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 45 to 90 cumulative days (ustic udic subclass).
Mean annual soil temperature: 38 to 42 degrees F.
Mean summer soil temperature: 42 to 46 degrees F. with an O horizon
Thickness of the mollic epipedon: 10 to 16 inches
Particle-size control section:
Clay content: 27 to 35 percent
Rock fragment content: 15 to 35 percent
A horizon:
Hue: 5YR or 7.5YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 1 to 3, dry and moist
Reaction: moderately acid or slightly acid
Bt horizon:
Hue: 2.5YR or 5YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2 to 4, dry and moist
Texture, fine earth fraction: CL
Rock Fragment content: 5 to 35 percent in the upper part and 20 to 60 percent in the lower part.
Reaction: slightly acid or neutral
COMPETING SERIES: These are the Hourglass, Mult, and Wildcow series. In addition, the following series may be competitors when their classification is updated: Buffork, Cific, Dra, Gebson, Lyonman, Michelson, Monida, Newlands, Passcreek, Primeaux, Rammel, Shotgun, Swede, Tripit, and Zade series.
Buffork,
Cific,
Tripit, and
Zade soils: have a paralithic contact above a depth of 40 inches.
Dra,
Mult,
Newlands,
Passcreek,
Primeaux,
Rammel,
Shotgun, soils: have a lithic contact above a depth of 40 inches.
Gebson,
Michelson, and
Monida soils: have a horizon of secondary calcium carbonate accumulation.
Hourglass soils: have rock fragments of sandstone and limestone.
Lyonman soils: formed in material derived from andesite or basalt.
Swede soils: have less than 15 percent (weighted average) rock fragments in the particle-size control section.
Wildcow soils: are slightly alkaline and have hue yellower than 5YR in the Bt horizon.
GEOGRAPHIC SETTING:
Parent material: slope alluvium and colluvium derived mostly from granite, gneiss, schist, and sandstone.
Landform: mountain slopes.
Slopes: 15 to 45 percent
Elevation: 8,500 to 10,000 feet
Mean annual air temperature: 36 to 42 degrees F.
Mean annual precipitation: 25 to 35 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 moist from snowmelt.
Frost-free period: 60 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Tuckerville and
Clayburn series.
Tuckerville soils have more than 35 percent rock fragments in the control section, and are on mountain slopes.
Clayburn soils have thicker dark colored surface layers, and are on alluvial fans and toeslopes.
DRAINAGE AND PERMEABILITY: Well drained; medium to high runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used for livestock grazing, timber production, and wildlife habitat. Native vegetation consists of quaking aspen, Rocky Mountain Douglas fir, white fir, snowberry, aspen peavine, Thurber's fescue, needlegrass, mountain brome, western wheatgrass, and sedges (quaking aspen/mountain snowberry plant association).
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: La Plata County, Animas-Dolores Area, Colorado, 1990. The name is coined.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: The zone from 1 to 12 inches. (A1 and A2 horizons)
Argillic horizon: The zone from 12 to 61 inches. (Bt1, Bt2, and Bt3 horizons)
Particle size control section: The zone from 12 to 32 inches. (Bt1 and part of the Bt2 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.