LOCATION UNSON WYTentative Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Typic Haplocambids
TYPICAL PEDON: Unson gravelly loam - grassland (Colors are for dry soil unless otherwise noted)
A1--0 to 3 inches; light brownish gray (10YR 6/2) gravelly loam, dark grayish brown (10YR 4/2) moist; moderate fine granular structure; soft, very friable, slightly plastic, slightly sticky; 25 percent gravel; calcareous; moderately alkaline, pH 8.2(CR); clear smooth boundary. (2 to 6 inches thick)
B2--3 to 15 inches; brown (10YR 5/3) gravelly heavy loam, dark brown (10YR 4/3) moist; weak coarse prismatic structure that parts to moderate medium subangular blocks; horizon is slightly hard, very friable, slightly plastic, slightly sticky; peds are hard; a few thin glossy patches on ped faces and discontinuous glossy coatings on the inside of some root channels and pores; 35 percent gravel; calcareous; moderately alkaline, pH 8.2 (CR); clear smooth boundary (5 to 28 inches thick)
Clca--15 to 24 inches; light gray (10YR 7/2) gravelly loam, grayish brown (10YR 5/2) moist; massive; hard, friable, slightly plastic, slightly sticky; 45 percent gravel; visible secondary carbonate occurring consistently in the form of small concretions and in seams and streaks; calcareous; moderately alkaline, pH 8.4 (CR); gradual wavy boundary. (6 to 33 inches thick)
C2ca--24 to 40 inches; light brownish gray (10YR 6/2) gravelly loam, dark grayish brown (10YR 4/2) moist, massive, hard, friable, slightly plastic, slightly sticky; 45 percent gravel; some visible secondary calcium carbonate as concretions and in thin seams and streaks; calcareous; moderately alkaline, pH 8.4 (CR)
TYPE LOCATION: Carbon County, Wyoming SE1/4 SE1/4 sec 12, T 18 N., R. 86 W.
RANGE IN CHARACTERISTICS: Unless otherwise noted the entire range of properties permissible for the diagnostic horizons or the subgroup and family are permissible for the series. Depth to uniformly calcareous material ranges from 0 to 10 inches but should not be deeper than the surface inch of the B2 horizon. Depth to continuous subhorizons of visible secondary calcium carbonate accumulation ranges from 10 to 40 inches. Exchangeable sodium ranges from 0 to 15 percent, in a major part of the control section and there should be no subhorizon more than 4 inches thick above 20 inches that exceed these limits. Weighted average gypsum content of the control section ranges from 0 to 5 percent and a majority of subhorizons above 15 inches should not exceed 3 percent. Depth to a lithic contact, a paralithic contact, or to skeletal materials ranges from 40 to more than 60 inches. Coarse fragments ranging from 1/2 to 10 inches in diameter predominate. Texture of the control section is typically a loam or clay loam, but clay may range from 18 to 35 percent, silt from 5 to 65 percent, and sand from 10 to 70 percent. Mottling not due to segregated lime ranges from no mottling to a few faint mottles but if the soil is mottled at all the chroma of the matrix material must exceed 2. The control section should be uniform with only minor stratification, Color of the A horizon may range in hue from 5Y to 7.5YR, in value from 5 to 7 dry and 3 to 6 moist, and in chroma from 1 to 4, Reaction normally ranges from mildly to moderately alkaline (1:5 dilution unbuffered organic dye). Color of the B2 horizon may range in hue from 5Y to 7.5YR, in value from 5 to 7 dry and 4 to 6 moist, and in chroma from 1 to 6, Reaction normally ranges from moderately to strongly alkaline (1:5 dilution unbuffered organic dye). Hue of the C horizon may range from 5Y to 7.5YR, and reaction normally ranges from moderately to strongly alkaline (1:5 dilution unbuffered organic dye). Calcium carbonate accumulation ranges from about 4 to 14 percent.
COMPETING SERIES: There are no other series in the same subgroup and family. Similar and related soils include the Chaperton and Sagecreek series. The Chaperton series differs in having less than 35 percent coarse fragments.
GEOGRAPHIC SETTING: The Unson series occurs on gently to moderately sloping old alluvial fans or high terraces. Slopes typically range from about 2 to 15 or more percent. The soil is developing in thick, calcareous, gravelly and cobbly alluvial materials derived from a variety of sources. At the type location the mean annual precipitation is about 7 inches with peak periods of precipitation occurring in the spring and early summer months. Mean annual air temperature is 42 degrees F., mean summer air temperature is 65 degrees F., mean annual soil temperature is 46 degrees F.; and mean summer soil temperature is 64 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Hermering and Sagecreek series. The Hermering series differs in lacking a cambic horizon. The Sagecreek differs in having less than 35 percent coarse fragments.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium to slow. Permeability is moderate to rapid.
USE AND VEGETATION: These soils are used principally as native pastureland. Native vegetation includes threadleaf sedge, bluebunch wheatgrass, and Indian ricegrass.
DISTRIBUTION AND EXTENT: Present known distribution limited to southern and western Wyoming. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Sage Creek area, Carbon County, Wyoming, 1972. Series name is a coined name.
OSED scanned by NSSQA. Last revised by state on 2/72.