LOCATION HOPDRAW SDEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, mixed, frigid Typic Ustorthents
TYPICAL PEDON: Hopdraw cobbly loamy fine sand - on a southeast-facing slope of 45 percent under mountain mahogany, juniper, and pine at an elevation of 5000 feet. When described the soil was dry throughout. (Colors are for dry soil unless otherwise noted.)
A--0 to 3 inches; grayish brown (10YR 5/2) cobbly loamy fine sand, very dark grayish brown (10YR 3/2) moist; weak very fine granular structure; loose, very friable; 20 percent by volume of rock fragments; slight effervescence; moderately alkaline; clear wavy boundary. (1 to 6 inches thick)
C1--3 to 9 inches; pale brown (10YR 6/3) very gravelly loamy fine sand, brown (10YR 4/3) moist; single grain; loose; 35 percent by volume of rock fragments; strong effervescence; moderately alkaline; gradual wavy boundary. (4 to 12 inches thick)
C2--9 to 14 inches; light gray (10YR 7/2) very gravelly loamy fine sand, grayish brown (10YR 5/2) moist; single grain, loose; 40 percent by volume of rock fragments; violent effervescence; moderately alkaline; gradual wavy boundary. (0 to 10 inches)
C3--14 to 44 inches; very pale brown (10YR 8/4) very gravelly loamy fine sand, very pale brown (10YR 7/4) moist; single grain, loose; 45 percent by volume of rock fragments; violent effervescence; moderately alkaline; abrupt wavy boundary.
R--44 to 60 inches; pink (7.5YR 8/4) indurated sandstone, moderately alkaline.
TYPE LOCATION: Custer County, South Dakota; about 20 miles west and 1 mile south of Custer; 2500 feet south and 1200 feet east of the northwest corner of sec. 27, T. 3 S., R. 1 E.
RANGE IN CHARACTERISTICS: The depth to sandstone is more than 40 inches. Coarse fragments ranging in size from pebbles to 12 inch cobbles and fragstones cover up to 25 percent the surface and are throughout the A and C horizons. The rock fragments make up 35 to 75 percent by volume of the control section.
The A horizon has hue of 7.5YR or 10YR, value of 4 to 6 and 2 to 4 moist, and chroma of 2 or 3. It is gravelly or very gravelly, cobbly or very cobbly and flaggy or very flaggy loamy fine sand and fine sand. It contains 15 to 60 percent by volume of fragments of rock. It is neutral to moderately alkaline.
The C horizon has hue of 5YR, 7.5YR, or 10YR; value of 5 to 8 and 4 to 7 moist; and chroma of 2 to 6. It is very gravelly, very cobbly, and very flaggy loamy fine sand, loamy sand, fine sand, or sand. It contains 35 to 75 percent fragments by volume. It is slightly to strongly alkaline.
The R horizon is hard or extremely hard sandstone that has some cracks and fractures. It is neutral to strongly alkaline.
COMPETING SERIES: These are the Clark Fork, Nemote, Oraid, Quamon, and Tinsley series. Clark Fork, Nemote, and Oraid do not have carbonates. In addition, Oraid soils have hard bedrock at a depth of 20 to 40 inches. Quamon soils have dominantly coarse fragments of basalt and have a drier climate. Tinsley soils have coarse fragments other than sandstone and have a drier climate.
GEOGRAPHIC SETTING: Hopdraw soils are strongly sloping to very steep on mountains at elevations of 3500 to 6200 feet. Slope gradients range from 10 to 75 percent. These soils formed in residuum and local colluvial sediments weathered from sandstone. They typically are on south or west aspects. Mean annual precipitation ranges from 16 to 26 inches, and mean annual temperature ranges from 37 to 45 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lakoa, Sawdust and Vanocker soils. The Lakoa and Vanocker soils are lower on the landscape, often on a northwest or north aspect. Lakoa soils have a fine-loamy control section and Vanocker soils are loamy-skeletal and both have an argillic horizon. The Sawdust soils have a loamy-skeletal control section and are on similar landscape position of the Hopdraw soils.
DRAINAGE AND PERMEABILITY: Excessively drained. Permeability is rapid. Runoff is low or medium.
USE AND VEGETATION: Used for wildlife, grazing and recreation. The native vegetation dominantly is a thin stand of ponderosa pine and Rocky Mountain Juniper with an understory of mountain mohagony, little bluestem, yucca, sideoats grama, skunkbush sumac, snowberry, western wheatgrass, junegrass, sand dropseed, blue grama and sedge.
DISTRIBUTION AND EXTENT: Mountain side slopes of the Black Hills in South Dakota and Wyoming, especially on the sedimentary beds surrounding the central crystalline area. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Custer County, South Dakota, 1985.
REMARKS: Diagnostic horizons and features recognized in this pedon are: ochric horizon - the zone from the surface to a depth of about 3 inches (A horizon).