LOCATION URACCA COEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Calcidic Argiustolls
TYPICAL PEDON: Uracca very cobbly loam, grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 4 inches; grayish brown (10YR 5/2) very cobbly loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable; 60 percent cobbles; noncalcareous; slightly alkaline; clear smooth boundary. (4 to 5 inches thick)
Bt--4 to 13 inches; brown (10YR 5/3) very cobbly sandy clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly plastic and slightly sticky; peds are hard, friable; thin patchy clay films on peds and as coatings and fillings in root channels and pores and on some coarse fragments; 60 percent cobbles; noneffervescent; slightly alkaline; clear smooth boundary. (5 to 15 inches thick)
C--13 to 17 inches; brown (10YR 5/3) very cobbly loamy sand, brown (10YR 4/3) moist; single grained; loose; 75 percent cobbles; noneffervescent; slightly alkaline; gradual smooth boundary. (3 to 5 inches thick)
Bk--17 to 60 inches; pale brown (10YR 6/3) extremely cobbly sand, brown (10YR 4/3) moist; single grained; loose; 80 percent cobbles; visible secondary calcium carbonate occurring as concretions and as coatings on the cobbles; strongly effervescent; moderately alkaline.
TYPE LOCATION: Alamosa County, Colorado; 500 feet west and 800 feet north of the southeast corner of Sec. 5, T. 29 S., R. 73 W.
RANGE IN CHARACTERISTICS:
Soil moisture: Ustic moisture regime bordering on Aridic
Mean annual soil temperature: 41 to 46 degrees F
Mean summer soil temperature: 63 to 66 degrees F
Depth to argillic horizon: 2 to 6 inches
Depth to calcic horizon: 11 to 38 inches
Depth to uniformly calcareous material: 6 to 40 inches (not shallower than the upper 3 inches of the Bt horizon)
Rock fragments: 35 to 85 percent by volume in a major part of the solum and B horizon above 50 inches and are typically more than 3 but less than 10 inches in diameter.
Particle-size control section (weighted average):
Clay content: 18 to 35 percent
Sand content: 20 to 75 percent
Rock fragment content: 35 to 85 percent
A horizon:
Hue: 2.5Y through 7.5YR
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 1 to 3
Fragments: 15 to 35 percent subrounded fine to coarse gravel, 0 to 15 percent subrounded cobbles
Calcium carbonate equivalent: 0 to 5 percent
Reaction: pH 6.6 to 8.4
Bt horizon:
Hue: 2.5Y through 7.5YR
Value: 4 to 7, 3 to 6 moist
Chroma: 1 to 6
Texture: very cobbly or extremely cobbly sandy clay loam, loam or clay loam, or very gravelly sandy clay loam
Clay content: 18 to 35 percent
Reaction: pH 6.6 to 7.8
C horizon (if present):
Hue: 2.5Y to 7.5YR
Value: 4 to 6 dry, 3 to 5 moist
Chroma: 2 to 4
Texture: very cobbly loamy sand, very cobbly sandy loam
Clay content: 5 to 18 percent
Reaction: pH 6.6 to 7.8
Bk horizon:
Hue: 2.5Y through 7.5YR
Value: 4 to 7 dry, 3 to 5 moist
Chroma: 2 to 4
Texture: very cobbly or extremely cobbly sandy loam, loamy sand, or sand
Clay content: 5 to 18 percent
Calcium carbonate equivalent:<p> 5 to 14 percent
Reaction: pH 7.4 to 9.0
COMPETING SERIES: These are the
Circleville,
Dullknife (T),
Ipson,
Nebies,
Sieben and
Widtsoe series.
Circleville soils: moderately deep to volcanic agglomerate bedrock
Dullknife soils: have lithic contact at 20 to 40 inches
Ipson soils: are predominantly gravelly and are deep
Nebies soils: dry in all parts between four-tenths and five tenths of the cumulative days per year when the soil temperature at 20 inches is 41 degrees F. or higher
Sieben soils: moist in some or all parts in most years more than half the time from April through October. These soils are frozen during the winter months..
Widtsoe soils: The soils are moist in some part of the moisture control section for more than 1/2 of the time the soil temperature is above 41 degrees F. They are dry in all parts of the soil between depths of 8 and 24 inches for less than 60 consecutive days within a 3 month period following the summer solstice in more than 7 out of 10
GEOGRAPHIC SETTING:
Landform: Alluvial fans, fan remnants, valley side slopes, and mountain slopes on the outer edges of high mountain basins and valleys
Slopes: 3 to 65 percent
Elevation: 7,600 to 10,500 feet
Mean annual temperature: 41 degrees F
Mean annual precipitation: 12 to 16 inches
Parent material: The soils formed in very cobbly and gravelly fan sediments derived from mixed rocks, and colluvium over residuum derived from granite, gneiss, and mica schist.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Comodore, Costilla, Culebra and Morval soils. Commodore and Culebra soils have a lithic contact at depths of less than 20 inches. Costilla soils are coarse textured and lack argillic horizons. Morval soils are fine-loamy.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderate permeability.
USE AND VEGETATION: These soils are used principally as native pastureland. Occasionally they are used for forestry. They yield small amounts of firewood or fence posts. They are also important for wildlife. Principal native vegetation is twoneedle pinyon, Rocky Mountain juniper, winter fat, mountain muhly, blue grams, junegrass, mutton grass, oatgrass, and needleandthread.
DISTRIBUTION AND EXTENT: South-central Colorado, MRLA 51, LRR E. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Alamosa County, Colorado, 1974.
REMARKS: OSED scanned by and cleaned up by Colorado. Last revised by state on 9/74.
Taxonomic Version: Tenth Edition, 2006