LOCATION VARDEN COEstablished Series
TAXONOMIC CLASS: Loamy-skeletal over fragmental, mixed, superactive Typic Haplocryolls
TYPICAL PEDON: Varden very cobbly loam, on a southeast facing, simple, 30 percent slope in rangeland at an elevation of 10,700 feet. (Colors are for dry soil unless otherwise noted.)
A--0 to 15 inches; dark grayish brown (10YR 4/2) very cobbly loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; 15 percent gravel, 30 percent cobble and 10 percent stones; neutral (pH 6.6); gradual wavy boundary. (10 to 16 inches thick)
2C1--15 to 30 inches; brown (7.5YR 5/2) extremely cobbly loam, brown (7.5YR 4/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; about half of volume not occupied by rock fragments is voids; 10 percent gravel, 60 percent cobble, and 15 percent stones; neutral (pH 6.6); gradual wavy boundary. (10 to 25 inches thick)
2C2--30 to 60 inches; brown (7.5YR 5/2) extremely cobbly loam; brown (7.5YR 4/2) moist; massive, slightly hard, friable, slightly sticky and slightly plastic; about half of volume not occupied by rock fragments is voids; 10 percent gravel, 60 percent cobbles, and 15 percent stones; neutral (pH 6.6).
TYPE LOCATION: San Juan County, Colorado; about 10 miles west of Silverton, Colorado, along South Mineral Creek road, south of South Mineral Creek Campground; located in an unsectionized area about 2,400 feet east and 150 feet north of the projected southwest corner of Sec. 19, T. 41 N., R. 8 W.; Ophir USGS quad; lat. 37 degrees 47 minutes 26 seconds N. and long. 107 degrees 47 minutes 38 seconds W., NAD 27
RANGE IN CHARACTERISTICS:
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: 48 to 55 degrees F.
Surface rock fragments: 3 to 15 percent
Thickness of the mollic epipedon: 10 to 16 inches
Depth to the top of the fragmental material: 13 to 35 inches
Particle-size control section:
Clay content: 10 to 27 percent in the upper part
Rock fragment content: 35 to 65 percent in the upper part, and 75 to 95 percent in the lower part
Fine earth content, lower part: 0 to 10 percent; large voids range from 5 to 20 percent
A horizon:
Hue: 5YR to 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 1 to 3, dry and moist
Rock fragment content: 35 to 65 percent
Reaction: moderately acid to neutral
2C horizon:
Hue: 5YR to 10YR
Value: 5 to 7 dry, 4 or 5 moist
Chroma: 2 to 6, dry and moist
Texture (fine earth fraction): L, SCL
Rock fragment content: 75 to 95 percent
Reaction: moderately acid to neutral
COMPETING SERIES: There are currently no competing series in this family. A similar soil is the Handran series. Handran soils do not have fragmental layers.
GEOGRAPHIC SETTING:
Parent material: alluvium, slope alluvium, and colluvium derived mainly from rhyolite, tuff, andesite, breccia, andsandstone, and some glacial debris.
Landform: mountain slopes, alluvial fans, and valley sides.
Slopes: 10 to 65 percent
Elevation: 9,000 to 11,500 feet
Mean annual air temperature: 32 to 38 degrees F.
Mean annual precipitation: 25 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 moist from snowmelt.
Frost-free period: 40 to 65 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Quazar, Needleton, and Snowdon series. All are on mountain slopes.
Quazar soils have argillic horizons, and are also on alluvial fans and valley sides.
Needleton soils do not have mollic epipedons.
Snowdon soils are shallow to a lithic contact.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability in the upper part, very rapid in the fragmental layer.
USE AND VEGETATION: These soils are used for livestock grazing, wildlife habitat, and recreation. Vegetation consists of Thurber's fescue, nodding brome, bluegrass, Parry's danthonia, shrubby cinquefoil, common juniper, and forbs.
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 ESTABLISHED: Ouray Area, Colorado. 1998. The typical pedon is in the Animas-Dolores Soil Survey Area, Colorado. Series proposed in 1988.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: The zone from 0 to 15 inches. (A horizon)
Particle-size control section: The zone from 10 to 40 inches (part of the A, the 2C1, and part of the 2C2 horizon)
Fragmental material: from 15 to 60 inches (2C1 and 2C2 horizons).
Keys to Soil Taxonomy: Classified according to the Eighth Edition, 1998.
The superactive CEC activity class is presumed for this series based on the general trend indicated by lab data throughout this region.