LOCATION HARPER TXEstablished Series
TAXONOMIC CLASS: Clayey, smectitic, thermic Lithic Haplustolls
TYPICAL PEDON: Harper clay, very stony--rangeland. (Colors are for dry soil unless otherwise stated.)
A1--0 to 7 inches; black (10YR 2/1) clay, black (10YR 2/1) moist; weak fine subangular blocky and granular structure; hard, firm, sticky and plastic; common fine and medium roots; 5 to 15 percent of cobble and stone size fragments on the surface; less than 5 percent of limestone fragments in the soil; noncalcareous; moderately alkaline; gradual smooth boundary. (4 to 8 inches thick)
A2--7 to 17 inches; black (10YR 2/1) clay, black (10YR 2/1) moist; moderate fine and medium angular blocky structure; hard, firm, sticky and plastic; common fine and medium roots; noncalcareous; moderately alkaline; abrupt wavy boundary. (7 to 12 inches thick)
R--17 to 18 inches; indurated, fractured dolomitic limestone bedrock.
TYPE LOCATION: Gillespie County, Texas; From intersection of U.S. Highway 290 and Ranch Road 1631 in Fredericksburg, 7.1 miles east on Ranch Road 1631 to junction with Ranch Road 2721, 8.2 miles east on Ranch Road 2721, 2.3 miles north on Grape Creek county road, 0.7 mile north and east on private road to Roy Jacoby ranch house, 0.3 mile east on field road, 50 feet east in rangeland.
RANGE IN CHARACTERISTICS: Thickness of the solum and depth to indurated limestone ranges from 11 to 20 inches. The amount of limestone fragments, rocks, and boulders on the surface ranges from 3 to 50 percent. Boulders range in size from 1 to 8 feet across the long axis, are flat and tilted at 30 to 45 degree angles. Limestone cobble and pebble fragments in the soil are angular and range from 0 to 10 percent. These fragments range from 2 to 6 inches along the long axis and 1 to 3 inches wide.
The A horizon has hue of 10YR, value of 2 or 3, and chroma of 1 or 2. Clay content ranges from 40 to 60 percent. It is mildly or moderately alkaline and noncalcareous.
The R layer is indurated dolomitic limestone or dolomite.
COMPETING SERIES: These include the Oglesby series in the same family and the similar Hensley, Kavett, Purves, Speck, Stephen, and Tarrant series. Oglesby soils are dry in the moisture control section for less than 90 days during most years. Hensley soils lack a mollic epipedon. Kavett soils have a petrocalcic horizon over limestone. Purves and Tarrant soils have calcic horizons, and in addition, Tarrant soils have skeletal control sections. Speck soils have an argillic horizon. Stephen soils have a paralithic contact with underlying chalk.
GEOGRAPHIC SETTING: Harper soils are on gently sloping to undulating uplands with plane to convex surfaces. Slope gradients range from 0 to 8 percent, but are predominantly 2 to 5 percent. The soil formed over limestone bedrock. Rock outcrop and stones and boulders are common to the landscape. It is dry in the moisture control section for more than 90 days in most years. The climate is dry subhumid. The mean annual precipitation ranges from 22 to 32 inches and the mean annual temperature ranges from 65 to 68 degrees F. The frost free season ranges from 215 to 235 days and elevation ranges form 1,000 to 2,300 feet. Thornthwaite annual P-E indices range from 31 to 44.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Stephen and Tarrant series.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is low on 0 to 1 percent slopes, moderate on 1 to 5 percent slopes, and high on 5 to 8 percent slopes. Permeability is moderately slow.
USE AND VEGETATION: Used as rangeland. Native grasses are bluestem, Texas wintergrass, and sideoats grama. Woody vegetation consists of a few live oak, elm, and juniper trees.
DISTRIBUTION AND EXTENT: Mainly in Central Basin and Edwards Plateau of west-central Texas. The soil is of small extent.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Gillespie County, Texas; 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon--0 to 17 inches (A1 and A2 horizons)
Lithic contact-- Hard limestone at 17 inches.