LOCATION LONE ROCK CO+MT WYEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, mixed, frigid Typic Haplustolls
TYPICAL PEDON: Lone Rock gravelly sandy loam. (Colors are for dry soil unless otherwise noted)
A--0 to 9 inches; dark grayish brown (10YR 4/2), gravelly sandy loam, very dark grayish brown (10YR 3/2); moderate fine granular structure; soft, very friable, nonsticky and nonplastic; few visible mica fragments as fine and very fine sand; 20 percent gravel and 10 percent cobbles; neutral (pH 6.7); clear smooth boundary. (7 to 10 inches thick)
AC--9 to 13 inches; brown (10YR5/3) very gravelly loamy sand, dark brown (10YR 3/3) moist; single grained; loose, nonsticky and nonplastic; common fine and few medium roots; few visible mica fragments as fine and very fine sand; 30 percent gravel, 5 percent cobbles and 2 percent stones; neutral (pH 6.8); clear wavy boundary. (3 to 12 inches thick)
C1--13 to 28 inches; yellowish brown (10YR 5/4) very gravelly loamy sand, dark yellowish brown (10YR 3/4) moist; single grain; loose, nonsticky and nonplastic; few fine and very fine roots; common visible mica fragments as fine and very fine sand; 45 percent gravel and 7 percent cobbles; neutral (pH 6.8); gradual wavy boundary. (6 to 21 inches thick)
C2--28 to 60 inches; light yellowish brown (10YR 6/4) extremely gravelly sand, dark yellowish brown (10YR 4/4) moist; single grain; loose, nonsticky and nonplastic; few very fine roots; 60 percent gravel and 10 percent cobble; neutral (pH 6.8).
TYPE LOCATION: Clear Creek County, Colorado; about 400 feet south and 800 east of the northwest corner of Sec. 34, T. 3 S., R. 74 W.; longitude: 105 degrees, 39 minutes, 24 seconds W.; latitude: 39 degrees, 45 minutes, 46 seconds N.
RANGE IN CHARACTERISTICS:
Soil moisture: Udid bordering on ustic moisture regime.
Mean annual soil temperature: 40 to 45 degrees F
Mean summer soil temperature: 58 to 64 degrees F
Thickness of mollic epipedon: 9 to 15 inches.Particle-size control section (weighted average): 10 to 40 inches
Clay content: 3 to 14 percent
Sand content: 70 to 90 percent
Rock fragments: 35 to 80 percent dominantly gravel but some cobbles and stones occur
A horizon:
Hue: 10YR or 7.5YR
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 1 through 3.
Reaction: slightly acid to neutral.
AC horizon:
Hue: 10YR or 7.5YR
Value: 4 through 7 dry, 3 through 6 moist.
Chroma: 2 through 4.
Texture: sandy loam, coarse sandy loam, fine sandy loam modified by rock fragments
Clay content: 4 to 14 percent
Reaction: slightly acid to neutral.
C horizon(s):
Hue: 10YR through 5YR
Texture: sand, loamy sand, loamy coarse sand modified by rock fragments
Reaction: slightly acid to slightly alkaline.
COMPETING SERIES: This is the Dominic (MT) and Holman (NM) series. Dominic and Holman soils contain more than 35 percent by volume rock fragments that are larger than 3 inches throughout the textural control section.
GEOGRAPHIC SETTING:
Parent material: alluvium derived from micaceous schist, granite, or other igneous rocks
Landform: fans and terraces of the mountains
Slopes: 0 to 50 percent
Elevation: 3,200 to 8,500 feet
Mean annual temperature: 39 to 45 degrees F
Mean annual precipitation: 14 to 24 inches
Frost-free period: 50 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Breece, Trag, and Garber series. Breece soils have mollic epipedons greater than 16 inches and less than 35 percent coarse fragments throughout the profile. Trag soils have an argillic horizon(s) with 18 to 35 percent clay. Garber soils contains 14 to 30 percent clay in the particle-size control section.
DRAINAGE AND PERMEABILITY: Well to somewhat excessively drained; slow to medium runoff; very rapid permeability.
USE AND VEGETATION: These soils are used for watershed, rangeland, and wildlife habitat. Some small areas are used for home site development. Native vegetation consists of muttongrass, needleandthread, western wheatgrass, Letterman needlegrass, mountain muhly, snowberry, wax currant, and mountain avens.
DISTRIBUTION AND EXTENT: Lone Rock soils occur in north central Colorado and western Montana. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Bitterroot Valley Area, Montana, 1952.
REMARKS:
Cambic subsoil horizons may exist when the texture of the subsoils above 20 inches are finer than very fine sand.
Series control section: The zone is in 10 to 40 inch depths.
The responsibility for the series and the type location has been transferred from the Bitterroot Valley Area of Montana to Clear Creek County, Colorado, for use in the Georgetown Area Soil Survey. This action is by agreement, 4/89, with Montana and is approved by the NSSQAS.
Taxanomic Version: Eighth Edition, 1998