LOCATION MARSHBROOK SDEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Cumulic Endoaquolls
TYPICAL PEDON: Marshbrook - on a 3 percent concave north-facing slope in grassland. (Colors are for moist soil unless otherwise stated.)
A1--0 to 9 inches; very dark brown (10YR 2/2) loam, very dark grayish brown (10YR 3/2) dry; moderate fine and medium granular structure; soft, very friable; neutral; clear smooth boundary.
A2--9 to 25 inches; very dark grayish brown (10YR 3/2) loam, dark grayish brown (10YR 4/2) dry; common medium distinct reddish brown (5YR 4/4) mottles; weak medium subangular blocky structure; hard, friable; neutral; gradual wavy boundary. (Combined A horizons is 8 to 38 inches thick.)
Bg--25 to 41 inches; dark grayish brown (10YR 4/2) loam, grayish brown (10YR 5/2) dry; common medium distinct reddish brown (5YR 4/4) mottles; very weak coarse subangular blocky structure; hard, friable; neutral; gradual wavy boundary. (0 to 36 inches thick)
Cg1--41 to 50 inches; very dark grayish brown (10YR 3/2) gravelly loam, dark grayish brown (10YR 4/2) dry; many medium prominent reddish brown (5YR 4/4) mottles; massive; hard, friable; 25 percent coarse fragments; neutral; gradual wavy boundary.
Cg2--50 to 60 inches; very dark gray (10YR 3/1) gravelly sandy loam, dark gray (10YR 4/1) dry; common fine and medium prominent reddish brown (5YR 4/4) mottles; massive; slightly hard, friable; 15 percent coarse fragments; neutral.
TYPE LOCATION: Pennington County, South Dakota; approximately 5 miles north and 11 miles west of Hill City; 1300 feet south and 1100 feet east of the northwest corner of sec. 32, T. 1 N., R. 3 E.
RANGE IN CHARACTERISTICS: The mollic epipedon ranges from 24 to 50 inches thick. Depth to carbonates ranges from 40 to 60 inches or more. The control section typically is loam or clay loam and has 18 to 35 percent clay, 20 to 55 percent silt, and 20 to 55 percent sand, with less than 35 percent fine or coarser sand. Rock fragments range from 0 to 15 percent in most subhorizons of the control section and are mainly 1/2 to 10 inches in diameter. Organic matter decreases uniformly with depth and usually is greater than .3 percent at depth of 50 inches.
The A horizon has hue of 5Y to 7.5YR, value of 2 or 3 and 3 to 5 dry, and chroma of 3 or less. It is loam or clay loam and is slightly acid to slightly alkaline. It has common distinct to many prominent mottles in the lower part.
The Bg horizon has hue of 5Y to 7.5YR, value of 4 to 6 and 5 to 7 dry, and chroma of 3 or less. It typically is loam or clay loam but some pedons have lenses of silt loam or fine sandy loam. It has common distinct to many prominent mottles. It ranges from slightly acid to slightly alkaline.
The Cg horizon has hue of 5Y to 10YR, value of 3 to 6 and 4 to 7 dry, and chroma of 1 to 3. It is gravelly loam, gravelly sandy loam, loam or clay loam. Rock fragments range from 0 to 35 percent by volume. It ranges from neutral to moderately alkaline.
COMPETING SERIES: These are the Kovich, Marshdale, Sibannac, and Welch series. Kovich soils have a stratified control section in which organic material decreases irregularly with depth and have loamy-skeletal substratums above a depth of 40 inches. Marshdale soils have a drier soil moisture control section for a longer period. Sibannac soils are moderately or slightly acid and have irregular decrease of organic carbon content with depth. Welch soils have a stratified control section in which organic matter decreases irregularly with depth and have a significant component of volcanic ash.
GEOGRAPHIC SETTING: The Marshbrook soils are on concave drainageways. Slopes typically range from about 0 to 10 percent. The soils formed in thick medium to moderately fine textured noncalcareous materials weathered principally from slate, quartzite, and schist. The mean annual precipitation ranges from 16 to 26 inches with peak periods of precipitation in the spring and early summer. Mean annual temperature ranges from 37 to 45 degrees F. Growing season is about 50 to 100 days; average growing season precipitation from 14 to 18 inches; and growing degree days are about 2500 to 2700.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Citadel, Cordeston, Heely, Maitland, Pactola, Vanocker, and Virkula soils. All of these well drained soils do not have mottles within depths of 30 inches and are on higher parts of the landscape.
DRAINAGE AND PERMEABILITY: Somewhat poorly or poorly drained; runoff is low or very high. Permeability is moderately slow.
USE AND VEGETATION: Used as grazing land or as hay meadow. Native vegetation is reedgrass, big bluestem, prairie cordgrass, and Kentucky bluegrass. It is rushes, cattail, sedges, willows in the wetter areas.
DISTRIBUTION AND EXTENT: Black Hills of South Dakota. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Pennington County, South Dakota, 1985.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of about 25 inches (A1 and A2 horizons).