LOCATION AMSDEN WY+UTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Ustic Argicryolls
TYPICAL PEDON: Amsden loam, grassland. (Colors are for air dry soil unless otherwise noted.)
A11--0 to 4 inches; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; moderate fine granular and crumb structure; soft, very friable, sticky and slightly plastic; neutral (pH 7.0); clear smooth boundary. (3 to 6 inches thick)
A12--4 to 8 inches; brown (7.5YR 4/2) loam, very dark brown (7.5YR 2/2) moist; moderate medium subangular blocky structure that parts to moderate fine granules; slightly hard, very friable, sticky and slightly plastic; neutral (pH 7.0); clear smooth boundary. (0 to 5 inches thick)
B1--8 to 12 inches; reddish brown (5YR 5/3) loam, dark reddish brown (5YR 3/3) moist; weak medium prismatic structure that parts to moderate medium subangular blocks; slightly hard, very friable, sticky and plastic; few thin waxy patches on all faces of peds; neutral (pH 7.0);clear smooth boundary. (3 to 6 inches thick)
B2t--12 to 23 inches; reddish brown (5YR 5/3) clay loam, reddish brown (5YR 4/3) moist; moderate medium prismatic structure that parts to moderate medium subangular blocks; extremely hard, friable, sticky and plastic; thin continuous waxy coatings on faces of peds; neutral (pH 7.2); clear smooth boundary. (5 to 15 inches thick)
B3ca--23 to 30 inches; reddish brown (5YR 5/3) clay loam, reddish brown (5YR 4/3) moist; weak medium prismatic structure that parts to weak medium subangular blocks; hard, friable, sticky and plastic; few thin waxy patches principally on vertical faces of peds; weak accumulation of secondary calcium carbonate as soft masses; calcareous; moderately alkaline (pH 8.0); diffuse wavy boundary. (4 to 8 inches thick)
Cca--30 to 60 inches; light reddish brown (5YR 6/3) clay loam, reddish brown (5YR 5/3) moist; massive; hard, friable, sticky and plastic; moderate accumulation of secondary calcium carbonate as soft masses and thin seams and streaks; calcareous, moderately alkaline (pH 8.2).
TYPE LOCATION: Johnson County, Wyoming; near the center of sec. 29, T.46N., R.84W.
RANGE IN CHARACTERISTICS: The mollic epipedon is 7 to 15 inches thick. Depth to calcareous material ranges from 15 to 30 inches. The solum is 15 to 40 inches thick. Organic carbon ranges from 1 to 3 percent in the surface horizon and decreases uniformly with depth. Gravel is 0 to 12 percent. Cobbles are 0 to 3 percent. Mean annual soil temperature ranges from 32 degrees to 47 degrees F., and mean summer soil temperature from 40 degrees to 58 degrees F., without an O horizon.
The A1 horizon has hue of 10YR through 5YR, value of 4 or 5 dry, 2 or 3 moist and chroma of 2 or 3. Typically its primary structure is granular or crumb, but is subangular blocky in some pedons. This horizon is neutral or mildly alkaline.
The B2t horizon has hue of 5YR through 10R, value of 5 or 6 dry, 3 through 5 moist and chroma of 2 through 4. It is loam or clay loam and has 1 to 35 percent clay, 20 to 50 percent silt, and 20 to 45 percent sand, with less than 35 percent fine sand or coarser. This horizon is neutral or mildly alkaline.
The Cca horizon has hue of 5YR through 10R. It is moderately or strongly alkaline and has 6 to 14 percent calcium carbonate equivalent.
COMPETING SERIES: These are the Croydon, Gelkie, Hourglass, Kezar, Leavitt, Lucky, Lymanson, Lyonman, Michelson, Miracle, Morset, Mult, Newlands, Passcreek, Philipsburg, Sponseller, Tingey, Tripit, Wellsville, Woosley, and Youga series. Croydon, Lyonman, Newlands, and Youga soils are noncalcareous. Gelkie soils have more than 35 percent fine or coarser sand in the B2t horizon. Hourglass soils lack a Ca horizon. Keazar, Lucky, Lymanson, Miracle, Mult, Passcreek, Sponseller, Tripit, and Woosley soils have bedrock at depths above 40 inches. Leavitt, Morset, and Tingey soils lack a lithochromic hue of 7.5YR or redder. Michelson, Philipsburg, and Wellsville soils have calcic horizons.
GEOGRAPHIC SETTING: The Amsden soils are on alluvial fans. Slope gradients typically range from about 2 to 20 percent. Elevation is 7,500 to 9,500 feet. The soils formed in thick, calcareous, reddish-colored sediments derived principally from calcareous redbed shale and siltstone. At the type location the annual average temperature is about 36 degrees F., and the summer temperature is about 42 degrees F. Mean annual precipitation is about 18 inches with peak periods of precipitation in the spring and early summer. The frost-free season is 60 to 65 days but frost may occur in any summer month.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Devoe, Decross, and Tripit soils. Devoe soils lack an argillic horizon and have a paralithic contact at depths of less than 20 inches. Decross soils have hue of 10YR or yellower, and have a mollic epipedon more than 16 inches thick. Tripit soils have a paralithic contact at depths of 20 to 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.
USE AND VEGETATION: These soils are used principally as native pastureland or for recreation purposes. Principal native vegetation is big sagebrush, Idaho fescue, canby bluegrass, Columbia needlegrass, and silvery lupine.
DISTRIBUTION AND EXTENT: High mountain areas of north-central Wyoming. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Johnson County (Southern Johnson County Area), Wyoming, 1971.