LOCATION PEPAL WYTentative Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Typic Haplocalcids
TYPICAL PEDON: Pepal fine sandy loam, rangeland - (Colors are for dry soil unless otherwise noted).
A1--0 to 1 inch; light brownish gray (10YR 6/2) fine sandy loam, dark grayish brown (10YR 4/2) moist; weak fine platy structure; soft, very friable, nonsticky, nonplastic; few very fine roots; strongly effervescent, lime disseminated; moderately alkaline (pH 8.0); clear wavy boundary. (1 to 3 inches)
B2--1 to 15 inches; pale brown (10YR 6/3) fine sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; soft very friable,nonsticky, nonplastic; common very fine an fine roots; strongly effervescent, lime in filaments and threads; moderately alkaline (pH 8.2); clear wavy boundary. (5 to 18 inches thick)
C1ca--15 to 30 inches; very pale brown (10YR 7/3) fine sandy loam, brown (10YR 5/3) moist; massive; slightly hard, very friable, slightly sticky, slightly plastic; few fine roots; violently effervescent, lime segregated in soft small masses and lenses and as crusts on gravel; moderately alkaline (pH 8.2); gradual wavy boundary. (6 to 50 inches thick)
C2--30 to 60 inches; light brownish gray (10YR 6/2) fine sandy loam, grayish brown (10YR 5/2) moist; massive; soft, very friable, slightly sticky, slightly plastic; few fine roots; strongly effervescent, lime mostly disseminated; moderately alkaline (pH 8.2).
TYPE LOCATION: Sweetwater County, Wyoming; NW1/4, NW1/4, Sec. 27, T21N, R110W about 8 miles west of Big Island Bridge on the Green River.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 43 degrees to 47 degrees F. The mean summer air temperature is 64 degrees to 68 degrees F. Gravel content is typically less than 15 percent but may range from 0 to 25 percent in any substratum. Depth to continuous horizons of carbonate accumulation ranges from 6 to 20 inches.
The A horizon has hue of 10YR or 2.5Y, value of 5 through 7 dry and 4 through 6 moist, and chroma of 2 or 3 dry and moist. Texture is fine sandy loam, sandy loam, or gravelly sandy loam with less than 25 percent gravel. The structure is platy or granular. Effervescence typically ranges from slight to strong, but some pedons may be leached free of carbonates in the thin strata. Reaction is mildly or moderately alkaline.
The C horizon has hue of 10YR or 2.5Y, value of 6 through 8 dry and 4 through 7 moist, and chroma of 2 through 4 dry and moist. Textures are fine sandy loam, sandy loam, or gravelly sandy loam. Thin strata of very gravelly sandy loam occur in some pedons. Coarse fragments range from 0 to 25 percent. Effervescence is strong or violent. Reaction is moderately or strongly alkaline. Calcium carbonate equivalent ranges from 15 to 35 percent in the calcic horizon.
COMPETING SERIES: These are McGinty and Teagulf (P) series. McGinty soils formed in alluvium from basalt and have 5 to 20 percent dark colored ferromagnesian mineral fragments. Teagulf soils have a paralithic contact at 20 to 40 inches.
GEOGRAPHIC SETTING: Pepal soils are on nearly level to sloping terraces and alluvial fans. Slopes range from 0 to 8 percent. They formed in mixed alluvium generated during the late Pliestocene epoch. Elevations range from 6,000to 7,000 feet. The mean annual precipitation is 6 to 9 inches. The mean annual air temperature is 38 to 45 degrees F., and summer air temperature is 61 degrees to 66 degrees F. The frost-free season is about 80 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Cambarge (P), Leckman (P), and competing Teagulf (P) soils. Cambarge soils are loamy-skeletal. Leckman soils do not have a calcic horizon. Teagulf soils have a paralithic contact at a 20 to 40 inch depth. These soils may occur intermixed with the Pepal soils depending upon the degree of dissection of the land form.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderately rapid permeability.
USE AND VEGETATION: These soils support native vegetation used mostly for domestic livestock grazing and wildlife habitat. Native vegetation at the type location is mainly big sagebrush, spiny hopsage, low rabbitbrush, shadscale, needleandthread, thickspike wheatgrass, Indian ricegrass, Sandberg bluegrass, pricklypear cactus, and phlox. These soils are well suited for irrigated cropland where water is available and are well suited for urban sites.
DISTRIBUTION AND EXTENT: Pepal soils occur in the Green River Basin of southwestern Wyoming. They are of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: 1979, Sweetwater County, Wyoming.
Classification updated to superactive Typic Haplocalcids from Typic Calciorthids December 1999. Description last updated by state March 1980.