LOCATION HILGRAVE TXEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, semiactive, thermic Aridic Haplustalfs
TYPICAL PEDON: Hilgrave very gravelly sandy loam - pasture. (Colors are for dry soil unless otherwise stated.)
A--0 to 7 inches, reddish brown (2.5YR 4/4) very gravelly sandy
loam, dark reddish brown (2.5YR 3/4) moist; weak granular structure; soft, very friable; many very fine roots and pores; contains 60 percent by volume siliceous gravel; neutral; clear smooth boundary. (5 to 10 inches thick)
Bt1--7 to 16 inches, red (2.5YR 5/6) extremely gravelly loam, red (2.5YR 4/6) moist; weak subangular blocky structure; soft, friable; common very fine roots and pores; clay bridging between sand grains; contains 65 percent by volume siliceous gravel; neutral; gradual smooth boundary. (4 to 14 inches thick)
Bt2--16 to 26 inches, red (2.5YR 5/6) extremely gravelly sandy clay loam, dark red (2.5YR 4/6) moist; weak subangular blocky structure; slightly hard, friable; few very fine roots and pores; evident clay films and bridging between sand grains; contains 75 percent by volume siliceous gravel; mildly alkaline; abrupt smooth boundary. (6 to 12 inches thick)
Bk--26 to 40 inches, red (2.5YR 5/6) gravelly loamy sand, (2.5YR
4/6) moist; massive; soft, very friable; few very fine roots and pores; contains 30 percent siliceous gravel, by volume, in upper part grading to 52 percent in lower part; few very fine films and threads of calcium carbonate; some pebbles have thin coatings of calcium carbonate; strong effervescence, moderately alkaline; abrupt wavy boundary. (6 to 18 inches thick)
C--40 to 60 inches, reddish yellow (5YR 6/6) coarse sand, yellowish red (5YR 4/6) moist; massive; soft, very friable; few gravel; moderately alkaline.
TYPE LOCATION: Cottle County, Texas; approximately 12 miles (airline) northwest of Paducah on the Matador Wildlife Refuge. The pedon site is 30 feet west of the ranch road and 1.3 miles, via ranch road, southwest of the windmill that is beside the ranch road; this location is 12.9 miles west of the Matador Wildlife Refuge Headquarters along the ranch road.
RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 20 to 50 inches. Depth to soft powdery secondary lime ranges from 16 to 28 inches. Gravel content ranges from 35 to 80 percent in at least the upper 20 inches of the Bt horizon, and usually throughout the solum.
The A horizon ranges from reddish brown (2.5YR 5/4; 5YR 5/3, 5/4), to light reddish brown (2.5YR 6/4; 5YR 6/3, 6/4), to light brown (7.5YR 6/4), to brown (7.5YR 5/3, 5/4). The texture varies from extremely gravelly sandy loam to gravelly loam. Reaction ranges from medium acid to moderately alkaline, but noncalcareous.
The Bt horizons are.red (2.5YR 5/6, 4/6), reddish brown (2.5YR 5/4, 4/4; 5YR 5/3, 4/3, 5/4, 4/4), or yellowish red (5YR 5/6, 4/6). The texture varies from very gravelly or extremely gravely sandy loam to very gravelly or extremely gravely sandy clay loam with at least 3 percent more clay than the overlying A horizon. The reaction ranges from slightly acid to moderately alkaline, but noncalcareous in the upper part.
The Bk horizon ranges from noncalcareous to calcareous in the matrix, with segregated calcium carbonate in the form of films and threads or coatings of calcium carbonate on the pebbles. The C horizon ranges from gravel-free sand to highly stratified gravel beds, containing strata of reddish earth.
COMPETING SERIES: There are no other soils in this family. Soils in similar families are the Devol, Gallegos, Grandfield, Miles, Mobeetie, Polar, and Springer series. Devol, Grandfield, Miles, and Springer soils have less than 35 percent gravel in the Bt horizon. Gallegos and Polar soils lack a Bt horizon. In addition, Polar soils have a calcic horizon. Mobeetie soils are calcareous throughout, lack a Bt horizon, and gravel content is less than 35 percent in the 10- to 40-inch control section.
GEOGRAPHIC SETTING: Strongly sloping, severely dissected hills with gradients of 3 to 30 percent. Ridge tops are narrow and discontinuous; surfaces are convex. The soils developed in stratified outwash resting on clean sands or gravel beds. The localities of probably occurrence have mean annual temperatures of 57 degrees to 66 degrees F., annual precipitation of about 18 to 26 inches; and Thornthwaite annual P-E indices of about 24 to 40.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Miles and Springer series.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate permeability
USE AND VEGETATION: All areas are in native range. The principal grasses are little bluestem and sand dropseed, with some sideoats, blue grama, black grama, and threeawn. Sand sagebrush, cacti, juniper trees, mesquite trees, and yucca shrub also grow on these soils. Many gravel pits are in some areas.
DISTRIBUTION AND EXTENT: Rolling Plains areas of west central Texas and possibly in similar areas of Oklahoma. Small extent.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Cottle County, Texas; 1970.
REMARKS: Previously mapped as a miscellaneous land type, hilly gravelly land. Diagnostic horizons and features recognized in this pedon are: Ochric epipedon - 0 to 7 inches, Argillic horizon - 7 to 26 inches