LOCATION SILVERN TXEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, siliceous, active, thermic Grossarenic Paleustalfs
TYPICAL PEDON: Silvern very gravelly loamy sand--rangeland.
(Colors are for dry soil unless otherwise stated.)
A1--0 to 10 inches; light brownish gray (10TYR 6/2) very gravelly loamy sand, dark grayish brown (10YR 4/2) moist; weak very fine granular structure; soft, very friable; many fine and very fine roots; siliceous pebbles comprise 60 percent by volume and siliceous cobbles comprise 9 percent by volume; medium acid; clear smooth boundary.
A2--10 to 22 inches; pinkish gray (7.5YR 6/2) very gravelly loamy sand, brown (7.5YR 5/2) moist; weak very fine granular structure; soft, very friable; common fine roots; siliceous pebbles comprise 51 percent by volume and siliceous cobbles comprise 27 percent by volume; medium acid; clear smooth boundary.
E--22 to 54 inches; pinkish gray (7.5YR 7/2) very gravelly loamy sand, brown (7.5YR 5/4) moist; weak fine and very fine subangular blocky structure; slightly hard, firm; few fine roots; siliceous pebbles mostly 1 to 3 inches in diameter comprise 62 percent by volume and cobbles comprise 10 percent by volume; strongly acid; clear wavy boundary. (Combined thickness of A and E horizons is 40 to 75 inches)
Bt1--54 to 62 inches; prominently and coarsely mottled yellowish red (5YR 5/8), light brown (7.5YR 6/4), and white (10YR 8/1) very gravelly sandy clay loam; weak fine and very fine subangular blocky structure; hard, firm, sticky and slightly plastic; few fine roots; plinthite comprises less than 2 percent by volume; common thick clay films on peds and in pores; siliceous pebbles comprise 50 percent by volume and cobbles comprise 11 percent by volume; very strongly acid; gradual wavy boundary. (6 to 18 inches thick)
Bt2--62 to 76 inches; dark red (10YR 3/6) very gravelly sandy clay loam; common medium prominent light gray (10YR 7/2) mottles; moderate fine and very fine subangular blocky structure; hard, firm, sticky and slightly plastic; very few fine roots; plinthite comprises less than 5 percent by volume; common clay films; siliceous pebbles comprise 54 percent by volume and cobbles comprise 9 percent by volume; very strongly acid; gradual smooth boundary. (10 to 24 inches thick)
C--76 to 80 inches; yellowish brown (10YR 5/8) gravelly sandy clay loam in aggregated matrix with light gray (10YR 7/2), massive, very firm, plastic clay and dark red (10R 3/6) firm reticulated masses and in plates coating coarse fragments; siliceous pebbles compise 23 percent by volume; very strongly acid.
TYPE LOCATION: DeWitt County, Texas; from the intersection of U.
S. Highways 87 and 183 and Cuero, Texas; 7.1 miles southeast on U. S. Highway 87; than 2.4 miles northeast and east on a county road to the northwest corner of a gravel pit; then 160 feet east on the road; and 10 feet south of road right-of-way.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 60 to more than 80 inches. Plinthite ranges from 0 to 5 percent by volume in the argillic horizon. Some pedons have a few dark concretions 2 to 6 mm in diameter throughout.
The A and E horizons ranges from 40 to 75 inches thick. It has hue of 7.5YR and 10YR, value of 5 to 7, chroma of 2 to 4. Texture is very gravelly loamy sand, very gravelly loamy fine sand or very gravelly sand. Coarse fragments consisting of siliceous pebbles mainly less than 1.5 inches in diameter and cobbles mainly 3 to 6 inches in diameter comprise from 35 to 90 percent by volume. Reaction ranges from strongly acid through neutral.
The Bt horizon is typically mottled in shades of red, gray, brown, and white. Colors is dominant by hue of 5YR to 10YR, value of 3 to 7, chroma of 1 to 8. It is commonly very gravelly sandy clay loam or gravelly sandy clay loam and less commonly gravelly sandy loam. Siliceous pebbles and cobbles range from 25 to 80 percent by volume. Reaction ranges from extremely acid to moderately acid with base saturation of 20 to 70 percent,
but is 35 percent or more in some part within 72 inches of soil surface.
The BC horizon, when encountered, and the C horizon have colors in shades of red, brown, gray, and yellow. Texture ranges from very gravelly sandy clay loam to gravelly sandy loam and is very strongly acid or strongly acid. Coarse fragments comprise 15 to
50 percent by volume.
COMPETING SERIES: There are no other series in the same family; other series in similar families include the Catilla, Ellen, Kuy, Patilo, and Vernia series. Catilla, Kuy, and Patilo soils have less than 35 percent coarse fragments. Ellen soils have an epipedon less than 40 inches thick. Kuy soils are in a udic moisture regime. Vernia soils have mixed mineralogy and do not have plinthite.
GEOGRAPHIC SETTING: Silvern soils are on gently sloping to gently rolling, convex uplands. Slope gradients are mainly 1 to 3 percent, but range to 8 percent. The soils formed in ancient stream terrace or delta deposits of sand and gravel mainly
associated with citronelle geology. Mean anual temperature is 70 degrees to 72 degrees F., average annual precipitation is 32 to 43 inches, and Thornthwaite annual P-E index is 42 to 64.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing
Catilla
and Eller series and the
Goldmire,
Straber, and
Tremona series which are on nearby similar positions. All of these soils, except Catilla have A horizons less than 40 inches thick. In addition, Straber and Tremona soils have less than 35 percent coarse fragments in the B2t horizon and have more than 35 percent clay in the control section.
DRAINAGE AND PERMEABILITY: Well drained, very slow runoff; rapid permeability in the surface horizons and moderate permeability in the subsoil.
USE AND VEGETATION: Mainly used as rangeland and mined locally
for gravel materials. Native vegetation is mostly post oak, blackjack oak, and elm trees with an understory of little bluestem, paspalum, panicum, and forbs.
DISTRIBUTION AND EXTENT: Mainly in the southern part of the Texas Claypan area of south Texas. The soil is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: DeWitt County, Texas; 1973.