LOCATION MIERHILL TXEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic, shallow Petrocalcic Paleustolls
TYPICAL PEDON: Mierhill very gravelly sandy loam, on a convex 12 percent slope, in rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 10 inches; grayish brown (10YR 5/2) very gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; hard, friable; many fine roots; few fine pores; 60 percent by volume of rounded and slightly angular igneous fragments, comprising about 50 percent gravel and 10 percent cobbles; neutral; clear smooth boundary. (5 to 13 inches thick)
Bt--10 to 18 inches; reddish yellow (7.5YR 6/6) extremely gravelly sandy clay loam, light brown (7.5YR 6/4) moist; moderate fine subangular blocky structure; hard, friable; few fine roots; 75 percent by volume of rounded and slightly angular igneous fragments, comprising 60 percent gravel and 15 percent cobbles; calcareous; moderately alkaline; abrupt smooth boundary. (5 to 8 inches thick)
Bkm1--18 to 24 inches; pinkish white (7.5YR 8/2) caliche; indurated and platy in upper four inches; strongly cemented in lower part; about 70 percent by volume of rounded and slightly angular igneous fragments; calcareous; moderately alkaline; gradual smooth boundary. (5 to 18 inches thick)
Bkm2--24 to 40 inches; very pale brown (10YR 8/2) caliche; weakly cemented; 70 percent by volume of rounded and slightly angular igneous fragments; calcareous; moderately alkaline.
TYPE LOCATION: Reeves County, Texas; .4 mile west of Interstate Highway 10 and FM 2903 intersection; 1.5 miles north on ranch road; 10 feet northeast of road in native rangeland.
RANGE IN CHARACTERISTICS:
Soil moisture: Aridic ustic moisture regime
Depth to indurated caliche is 10 to 20 inches
Rock fragments - volume of coarse igneous fragments in the A and B horizon is 50 to 85 percent.
Gravel - 45 to 70 percent
Cobbles - 0 to 25 percent
Stone - 0 to 10 percent
A horizon
Value: 2 to 5
Chroma: 1 to 3.
Texture: very gravelly sandy loam, sandy clay loam, or clay loam.
B2t horizon
Hue: 5YR or 7.5YR
Value: 5 or 6
Chroma: 4 to
Texture: extremely or very gravelly sandy clay loam, loam, or clay loam
Clay content: estimated at 18 to 35 percent.
Bkm horizon
Hue: 7.5YRor 10YR
Value: 7 or 8
Chroma: 2 or 3
Cementation: indurated in the upper part and weakly cemented in the lower part.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: These soils are on ridges and dissected uplands. Slopes range from 8 to 16 percent. These soils formed in thick gravelly and stony igneous alluvium, as dissected fans or terraces presumed to be of Quaternary of Pliocene Age. The climate is arid to semiarid continental. The average annual temperature is about 60 degrees to 68 degrees F., the average annual precipitation ranges from 10 to 16 inches, and Thornthwaite P-E indices about 12 to 22.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Boracho, Mitre, Brewster, Delnorte, Limpia, Reakor, and Vieja series. Brewster soils are over igneous rock. Delnorte soils lack a mollic epipedon and Bt horizon. Limpia and Reakor soils have sola thicker than 20 inches. Vieja soils are more clayey and have formed in clayey shale.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate permeability.
USE AND VEGETATION: Used as rangeland. Vegetation is mainly black grama, sideoats grama, cane bluestem, bush muhly, and a variety of forbs.
DISTRIBUTION AND EXTENT: Regions of igneous bedrock of western Texas and possibly New Mexico and Arizona. The series is of minor extent. MLRA 42.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Reeves County, Texas; 1976.
REMARKS: Diagnostic horizon and features recognized in this pedon are:
Mollic epipedon - the zone from 0 to 10 inches (A horizon)
Argillic horizon - the zone from 10 to 18 inches (Bt horizon)
Petrocalcic horizon - the zone at 18 inches (Bkm horizons)
Soil Taxonomy: Ninth Edition 2003