LOCATION ROBAY UTEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, siliceous, frigid Lithic Ustorthents
TYPICAL PEDON: Robay very cobbly fine sand, 12 percent slope at an elevation of 7430 feet. (Colors are for dry soil unless otherwise noted.) The surface is covered by 10 percent gravel, 35 percent cobbles and 5 percent stones.
A--0 to 3 inches; yellowish brown (10YR 5/4) very cobbly fine sand, dark yellowish brown (10YR 4/4) moist; single grain; loose, loose, nonsticky and nonplastic; common very fine and fine and few medium and coarse roots; 10 percent gravel, 40 percent cobbles and 2 percent stones; noneffervescent; slightly acid (pH 6.4); clear smooth boundary. (1 to 6 inches thick)
C--3 to 10 inches; dark yellowish brown (10YR 4/4) very cobbly fine sand, dark yellowish brown (10YR 3/4) moist; single grain; loose, loose, nonsticky and nonplastic; common very fine and few fine, medium and coarse roots; 20 percent gravel and 20 percent cobbles; noneffervescent; neutral (pH 6.6); abrupt smooth boundary. (5 to 15 inches thick)
R--10 inches; Navajo Formation sandstone.
TYPE LOCATION: Garfield County, Utah; about 6 miles north of Escalante; Dixie National Forest; about 1/2 mile east of the top of Roundy Trail; Escalante USGS quad; lat. 37 degrees 51 minutes 35.79 seconds N. and long. 111 degrees 36 minutes 27.42 seconds W. NAD 1983.
RANGE IN CHARACTERISTICS:
Soil moisture: The soil moisture control section is ustic, typic ustic subclass.
Mean annual soil temperature: 42 to 47 degrees F
Depth to lithic contact: 4 to 20 inches
Lithology of rock fragments: Navajo sandstone
Particle-size control section (weighted average)
Clay content: 1 to 6 percent
Rock fragments: 35 to 70 percent
A horizon:
Value: 4 to 6 dry, 3 to 5 moist
Chroma: 2 to 4, dry or moist
Reaction: slightly acid or neutral
C horizon:
Value: 4 to 6 dry, 3 to 5 moist
Chroma: 2 to 4, dry or moist; decomposing root material sometimes causes value of 5 dry, 3 moist chroma of 2 to occur 1 to 2 inches above the sandstone
Texture, fine earth fraction: fine sand, loamy fine sand, loamy sand, or sand
Rock fragments: 35 to 70 percent angular and subangular gravel, cobble and stones
COMPETING SERIES: There are no competing series in this family.
GEOGRAPHIC SETTING:
Parent material: eolian deposits, alluvium, and local residuum derived from Navajo sandstone
Landform: structural benches
Slopes: 5 to 40 percent
Elevation: 7200 to 7800 feet
Mean annual air temperature: 40 to 45 degrees F
Mean annual precipitation: 12 to 16 inches
Frost-free period: 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Strell series. The Strell soils have less than 15 percent rock fragments in the particle size control section.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained, low to medium runoff, rapid to very rapid permeability.
USE AND VEGETATION: These soils are used for woodland, rangeland, wildlife habitat and recreation. Potential native vegetation includes Ponderosa pine, manzanita, Utah serviceberry, Indian ricegrass, Nevada bluegrass, and muttongrass. These soils have been correlated to the Mountain Shallow Loam (Ponderosa Pine) 047XB450UT ecological site at the type location in Utah. This plant community reflects greater available moisture than the annual precipitation would indicate.
DISTRIBUTION AND EXTENT: South central, Utah, MLRA 47; This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Garfield County, Utah; Grand Staircase-Escalante National Monument Area, 2004. Typical pedon is in Dixie National Forest Soil Survey Area.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 3 inches. (A horizon)
Lithic contact: The contact with Navajo sandstone at 10 inches. (R layer)
Siliceous mineralogy: soils formed directly from Navajo sandstone contain more than 90 percent silica minerals (dominantly quartz).
The 9/2004 revision changes the moisture regime subclass from aridic ustic to typic ustic.
Taxonomic Version: Ninth Edition, 2003