LOCATION BROWNSTO WY+CO MT UTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Ustic Haplocalcids
TYPICAL PEDON: Brownsto gravelly sandy loam-native rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 6 inches; grayish brown (10YR 5/2) gravelly sandy loam, dark grayish born (10YR 4/2) moist; moderate fine granular structure; soft, very friable, nonsticky and nonplastic; many fine, medium, and common coarse roots; 30 percent pebbles; slightly effervescent, calcium carbonate disseminated; moderately alkaline (pH 8.2); clear wavy boundary. (3 to 7 inches thick)
Bk1--6 to 10 inches; brown (10YR 5/3) very gravelly sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many fine and medium and common coarse roots; 40 percent pebbles; strongly effervescent; common fine and medium threads and soft masses of calcium carbonate in lower part; moderately alkaline (pH 8.2); clear wavy boundary. (0 to 6 inches thick)
Bk2--10 to 25 inches; very pale brown (10YR 7/3) very cobbly sandy loam, brown (10YR 5/3) moist; weak very fine subangular blocky structure; hard, very friable, slightly sticky and slightly plastic; few medium and coarse roots to 18 inches; 30 percent pebbles, 15 percent cobbles, and 5 percent stones; violently effervescent, calcium carbonate pendants on underside of rock fragments and as soft masses in matrix; moderately alkaline (pH 8.4); gradual wavy boundary. (10 to 20 inches thick)
Bk3--25 to 60 inches; very pale brown (10YR 7/4) very cobbly sandy loam, brown (10YR 5/3) moist; massive, soft, very friable, slightly sticky and slightly plastic; 30 percent pebbles, 15 percent cobbles, and 5 percent stones; strongly effervescent, thin calcium carbonate coatings on some rock fragments; moderately alkaline (pH 8.0).
TYPE LOCATION: Sweetwater County, Wyoming; SW1/4 NW1/4 of sec. 28, T. 13 N., R. 105 W. Richards Gap Wyo. Quadrangle 41 degrees 4 minutes 44 seconds north latitude and 109 degrees 14 minutes 58 seconds west longitude.
RANGE IN CHARACTERISTICS:
Depth to secondary calcium carbonate accumulation: 4 to 15 inches.
Mean annual soil temperature: 44 to 46 degrees F.
Mean summer soil temperature: 59 to 65 degrees F.
Calcium carbonate equivalent is commonly more than 20 percent but ranges from 15 to 40 percent with some thin strata exceeding 40 percent.
Particle-size control section: 15 to 27 percent clay and more than 35 percent fine sand or coarser. Content of rock fragments is variable but ranges from 30 to 55 percent pebbles, 5 to 20 percent cobbles, and 0 to 15 percent stones
A horizon:
Hue: 7.5YR through 2.5Y
Value: 4 through 6 dry, 3 through 5 moist
Chroma: 2 through 4
When value is 3 moist, the horizon is too thin to be mollic.
Texture: gravelly sandy loam or cobbly sandy loam
Rock fragments: ranges from 5 to 50 percent pebbles, 0 to 30 percent cobbles, and 0 to 5 percent stones
Reaction: slightly alkaline or moderately alkaline
Bk horizon:
Hue: 7.5YR through 2.5Y
Value: 5 through 8 dry, 4 through 7 moist
Chroma: 2 through 6
COMPETING SERIES: These are the Browtine, Bruja, Bruman, and the Vermillion series.
Browntine: less than 15 percent clay in the particle-size control section
Bruja: paralithic contact at 20 to 40 inches deep
Bruman: have sandy-skeletal substratum
Vermillion: lithic contact at 20 to 40 inches deep
GEOGRAPHIC SETTING:
Parent material: Pleistocene pluvial sediments or modified glacial outwash
Landform: relict high energy alluvial fans, outwash fans, mountain toeslopes, and terraces
Slopes: 0 to 75 percent
Elevations: 6,000 to 7,800 feet
Mean annual precipitation: 10 to 14 inches, of which about half falls as snow or rain in April, May, and early June
Mean annual temperature: 40 to 45 degrees F.
Mean summer temperature: 57 to 66 degrees F.
Frost-free season: is estimated to be about 60 to 110 days, depending upon elevation, aspect, and air drainage.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Castello, Fiveoh, Goslin, McFadden, and the competing Crago soils. Castello, Fiveoh, Goslin, and McFadden soils have less than 35 percent rock fragments in their control section. Also, Castello soils have carbonatic mineralogy, and Goslin soils lack a calcic horizon.
DRAINAGE AND PERMEABILITY: Well drained, slow or medium runoff; moderately rapid permeability.
USE AND VEGETATION: Brownsto soils are used primarily for rangeland and wildlife habitat. Native vegetation at the type location is big sagebrush, bluebunch wheatgrass, prairie junegrass, black sagebrush, pricklypear, buckbrush, phlox, and nailwort.
DISTRIBUTION AND EXTENT: West and southwestern Wyoming; north and south central Colorado and south central Utah. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Sweetwater County, Wyoming; 1980
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 6 inches (A)
Calcic Horizon - 6 to 60 inches (Bk1,Bk2,Bk3)
MLRR- D
Taxonomic version: Eighth Edition, 1998.