LOCATION LEATHAM UTEstablished Series
TAXONOMIC CLASS: Fine-silty, carbonatic, frigid Typic Haploxerolls
TYPICAL PEDON: Leatham silt loam - native grasses and shrubs. (Colors are for dry soil unless otherwise noted.)
A1--0 to 4 inches; gray (10YR 5/1) silt loam, very dark gray (10YR 3/1) moist; weak medium platy structure that parts to moderate fine granular structure; soft, friable, nonsticky, slightly plastic; many fine, medium and large roots; many fine pores; strongly calcareous; neutral (pH 7.3); abrupt smooth boundary. (3 to 5 inches thick)
A2--4 to 10 inches; gray (10YR 5/1) silt loam, very dark gray (10YR 3/1) moist; weak coarse subangular blocky structure that parts to moderate fine subangular blocky structure; hard, friable, slightly sticky, slightly plastic; many fine, medium and large roots; many fine and medium and few large pores; strongly calcareous; neutral (pH 7.2); clear wavy boundary. (5 to 10 inches thick)
AC--10 to 15 inches; light gray (2.5Y 7/2) silty clay loam, grayish brown (2.5Y 5/2) moist; weak medium subangular blocky structure that parts to weak fine subangular blocky structure; very hard, friable, slightly sticky, slightly plastic; many fine and medium and few large roots; many fine and medium and few large pores; very strongly calcareous; neutral (pH 7.2); gradual wavy boundary. (3 to 6 inches thick)
Ck1--15 to 25 inches; pale yellow (2.5Y 8/2) silt loam, light brownish gray (2.5Y 6/2) moist; weak medium subangular blocky structure that parts to weak fine subangular blocky structure; very hard, friable, nonsticky, slightly plastic; many fine and medium and few large roots; many fine and medium pores; very strongly calcareous; slightly alkaline (pH 7.5); gradual wavy boundary. (8 to 12 inches thick)
Ck2--25 to 39 inches; white (2.5Y 8/1) silty clay loam, light gray (2.5Y 7/2) moist; massive; very hard, very friable, nonsticky, slightly plastic; few fine roots; many fine and medium pores; very strongly calcareous; slightly alkaline (pH 7.6); gradual irregular boundary. (10 to 20 inches thick)
Ck3--39 to 54 inches; same as Ck2 horizon except it contains many pockets of weathering volcanic ash which is noncalcareous and has colors lighter than N 8/. These pockets make up about 1/3 of the volume of the horizon.
TYPE LOCATION: Cache County, Utah; 1 1/2 miles east of Crow Mountain; 1,000 feet west of the E1/4 corner of sec. 12, T.13N., R.1E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 42 degrees to 47 degrees F., and the mean summer temperature at a depth of about 20 inches ranges from 62 degrees to 68 degrees F. The soils are usually moist but are dry for 60 to 75 continuous days in the 4 to 12 inch section in the summer and early autumn.
The mollic epipedon ranges from 8 to 12 inches thick. The carbonate equivalent is more than 40 percent in the top 40 inches. Cation exchange capacity/clay ratio is 0.6 to 0.9. The control section is silt loam or silty clay loam with more than 18 percent clay and less than 15 percent coarser than very fine sand.
The A horizon has value of 4 or 5 dry. It has weak thin or moderately thick platy to moderate fine granular structure in the upper part and weak fine subangular blocky structure in the lower part. This horizon ranges from neutral to moderately alkaline and is 8 to 12 inches thick. A transitional AC horizon usually is present between A and C horizons.
The Ck horizon has value of 7 or 8 dry, 5 through 7 moist, and chroma of 1 or 2. It is silt loam or silty clay loam. This horizon has weak fine to moderate subangular blocky structure or is massive. It ranges from slightly to strongly alkaline and is very strongly calcareous.
COMPETING SERIES: These are the Barfuss, Collinston, Green Canyon, and Millville series. Barfuss soils have argillic horizons and contain less than 40 percent carbonates. Collinston soils contain less than 40 percent carbonates. Millville, Green Canyon, and Collinston soils have mean annual temperatures of 47 degrees F. or more. Green Canyon soils have very gravelly control sections.
GEOGRAPHIC SETTING: Leatham soils are at elevations of 5,200 to 6,000 feet above sea level on very steep, dominantly south and west facing mountain slopes having gradients of 30 to 50 percent. They formed in residuum and colluvium from light colored tuff, conglomerate, tuffaceous sandstone, and limestone of the Salt Lake Geologic Formation. These materials contain considerable ash and have high cation exchange capacities. The climate is moist subhumid. Mean annual temperature is 42 degrees to 45 degrees F., mean summer temperature is 62 degrees to 65 degrees F. and the average annual precipitation is 20 to 24 inches. The frost-free period is 80 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Barfuss and Collinston soils and the Avon, LaPlatta, Mendon, and Wheelon soils. All of these soils contain less than 40 percent carbonates. Avon, LaPlatta, and Mendon soils have argillic horizons and have mean annual temperatures of 47 degrees or more. Wheelon soils lack mollic epipedons.
DRAINAGE AND PERMEABILITY: Well drained; medium to slow runoff; moderate to moderately slow permeability.
USE AND VEGETATION: These soils are used mainly as rangeland. The native vegetation is bluebunch wheatgrass, prairie junegrass, oniongrass, slender wheatgrass, Great Basin wildrye grass, western wheatgrass, balsamroot, buckwheat, geranium, sagebrush, serviceberry, snowberry, and phlox.
DISTRIBUTION AND EXTENT: Northern Utah. This series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Cache County, Utah, 1972.