LOCATION TELLURA COEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic Ustic Argicryolls
TYPICAL PEDON: Tellura clay loam - grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 10 inches, dark gray (10YR 4/1) clay loam, black (10YR 2/1) moist; strong fine granular structure; soft, very friable, slightly sticky and slightly plastic; 5 percent gravel and 5 percent cobbles; neutral; clear smooth boundary. (4 to 13 inches thick.)
BA--10 to 14 inches, dark gray (10YR 4/1) clay loam, black (10YR 2/1) moist; moderate fine subangular blocky structure parting to moderate coarse granular; slightly hard, very friable, slightly sticky and slightly plastic; few faint clay films ped faces and lining root channels and pores; 5 percent gravel and 5 percent cobbles; neutral; clear smooth boundary. (3 to 18 inches thick)
Bt1--14 to 30 inches, yellowish brown (10YR 5/4) very gravelly clay, dark yellowish brown (10YR 4/4) moist; moderate medium angular blocky structure; hard, friable, sticky and plastic; many prominent clay films on faces of peds and as coatings on the inside of root channels and pores; clay films also coat the outside of many rock fragments; 30 percent gravel and 10 percent cobbles; neutral; gradual smooth boundary. (5 to 40 inches thick)
Bt2--30 to 36 inches, yellowish brown (10YR 5/4) very gravelly clay, dark yellowish brown (10YR 4/4) moist; weak coarse angular blocky structure; hard, firm, sticky and plastic; few faint clay films on faces of peds and in root channels and pores; 35 percent gravel and 15 percent cobbles; neutral; gradual smooth boundary. (3 to 8 inches thick)
C--36 to 60 inches, brown (10YR 5/3) very gravelly clay loam, brown (10YR 4/3) moist; massive; extremely hard, very firm, sticky and plastic; 35 percent gravel and 15 percent cobbles; neutral.
TYPE LOCATION: San Miguel County, Colorado; about 12 miles northwest of Telluride; 600 feet north and 1,600 feet east of the southwest corner, Sec. 15, T. 44 N., R. 10 W. USGS. Sams quad.; Lat. 38 degrees, 03 minutes, 34 seconds N., and Long. 107 degrees, 57 minutes, 17 seconds W.
RANGE IN CHARACTERISTICS:
Soil moisture regime: The soil moisture control section is usually dry in some part in early summer, moist in some or all parts in late July and August, and intermittently dry in fall; ustic regime.
Mean annual soil temperature: 36 to 44 degrees F.
Depth to the base of the argillic horizon: 15 to 48 inches
A horizon:
Hue: 5Y through 7.5YR
Value: 3 through 5 dry, 2 or 3 moist
Chroma: 1 through 3, dry or moist
Reaction: slightly acid or neutral.
Bt horizon:
Hue: 5Y through 7.5YR
Value: 4 through 7 dry, 2 through 6 moist
Chroma: 1 through 6, dry or moist
Texture: clay, sandy clay, or clay loam with gravelly or cobbly modifiers
Clay content: 35 to 55 percent
Rock fragment content: 35 to 85 percent; including 10 to 60 percent gravel, 10 to 50 percent cobbles, and 0 to 5 percent stones
Reaction: slightly acid or neutral.
Some pedons have a BC horizon.
C horizon:
Hue: 5Y through 7.5YR
Value: 4 through 7 dry, 4 through 7 moist
Chroma: 2 through 6, dry or moist
Texture: loam, sandy clay loam, sandy clay, clay loam, or clay; with very gravelly, extremely gravelly, cobbly, or very cobbly modifiers
Rock fragment content: 35 to 85 percent; including 10 to 60 percent gravel, 10 to 50 percent cobbles, and 0 to 5 percent stones
Reaction: neutral or slightly alkaline
COMPETING SERIES:
The
Embargo (CO) soils have a lithic contact between 20 and 40 inches
The
Evna and
Passar soils have rock fragments which are dominantly of stone size.
The
Redchief (MT) soils are more than 48 inches deep to the base of the argillic horizon.
The
Rooset (WY) soils have horizons of secondary carbonate accumulation.
GEOGRAPHIC SETTING: Tellura soils are on high structural benches, fans, mountain slopes, and toe slopes. They formed in formed in very gravelly and cobbly colluvium or slope alluvium derived mainly from andesite, breccia, tuff, and shale, and in some places influenced from basalt. The type location is believed to be in an area of Mancos shale. Slopes are 2 to 65 percent. Elevation ranges from 8300 to 11,000 feet. Mean annual precipitation ranges from 14 to 25 inches with nearly equal amounts of precipitation in all months. In central Colorado, peak periods of precipitation are in spring and summer. Mean annual temperature is 32 to 44 degrees F, and mean summer temperature is 55 to 58 degrees F. The frost-free period is about 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Adel, Baird Hollow, Ceek, Hofly, Leaps, Nordicol, Ryman, and Skisams soils. Adel, Hofly, Leaps, and Ryman all have less than 35 percent rock fragments in the particle-size control section. Baird Hollow soils have an argillic horizon that has its upper boundary deeper than 24 inches. Ceek soils are frigid. Nordicol soils have less than 35 percent clay in their particle-size control section. Skisams soils have a lithic contact above 20 inches.
DRAINAGE AND PERMEABILITY: Well drained; medium or high or very high runoff; slow permeability
USE AND VEGETATION: These soils are used mainly as grazing land. Native vegetation consists of shrubby cinquefoil, Thurber fescue, Letterman needlegrass, slender wheatgrass, and mulesear wyethia. In central Colorado the vegetation is dominantly Arizona fescue, prairie junegrass, fringed sagebrush, mountain muhly, blue grama,
DISTRIBUTION AND EXTENT: Western and south-central Colorado. MLRA 48A. The series is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Saguache County Area, Colorado, 1981. The typical pedon is in the San Miguel soil survey area, Colorado. The name is coined from the town of Telluride.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: The zone from 0 to 14 inches (A and BA horizons)
Argillic horizon: from 14 to 36 inches (Bt and BCt horizons)
Particle-size control section: The zone from 14 to 34 inches (upper 20 inches of the argillic horizon)
The 2/1999 revision changes the classification from clayey-skeletal, montmorillonitic Argic Cryoborolls to clayey-skeletal, smectitic Ustic Argicryolls.
Keys to Soil Taxonomy: Classified according to Ninth edition, 2003.
The moisture regime of this series is not clear and needs investigation. It is currently considered to have an ustic regime, but a udic regime bordering ustic cannot be ruled out. The 2/1999 revision to an Ustic subgroup did not agree with the moisture regime given at that time as "udic bordering ustic"; this was changed to simply "ustic regime" on the 01/2010 revision.
ADDITIONAL DATA: This series has been sampled by the NSSL but results do not support the series, either because of insufficient clay, or by not having smectitic mineralogy, or by classifying in the Alfic subgroup.