LOCATION BIGBROWN TXEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, active, nonacid, thermic Typic Ustorthents
TYPICAL PEDON: Bigbrown silty clay loam--pasture.
(Colors are for dry soil unless otherwise stated.)
Ap--0 to 8 inches; grayish brown (10YR 5/2) silty clay loam dark grayish brown (10YR 4/2) moist; weak fine granular and weak fine platy structure; hard; friable, sticky and plastic; many very fine and fine roots; few fine fragments of lignite; common fine and medium fragments of shale; moderately alkaline; gradual wavy boundary. (2 to 10 inches thick)
C1--8 to 70 inches; grayish brown (10YR 5/2) silty clay loam; dark grayish brown (10YR 4/2) moist; massive; hard, friable, sticky and plastic; common very fine and fine roots in upper 20 inches; few very fine roots below; few (1 percent) fine fragments of lignite; common fine and medium fragments of grayish shale; random strata of lighter and darker materials ranging from silty clay to sandy loam; moderately alkaline; diffuse broken boundary. (36 to 80 inches thick)
C2--70 to 80 inches; reddish yellow 7.5YR 6/6) sandy clay loam strong brown (7.5YR 5/6) moist; massive; hard; friable, sticky and plastic; few very fine roots; common fine and medium fragments of shale; few thin layers of fine sandy loam; moderately alkaline.
TYPE LOCATION: Freestone County, Texas; from intersection with U.S. Highway 84 in Fairfield; 5.6 miles northeast on Farm Road 488; about 300 feet west. This is about 1000 feet west-southwest of Lakes Chapel Cemetery. Latitude 31 degrees 47' 42" N, Longitude 96 degrees 08' 38" W.
RANGE IN CHARACTERISTICS: Depth of minesoil materials is greater than 60 inches. Reaction ranges from medium acid through moderately alkaline throughout. Fragments of soft shale, fine-grained sandstone, and ironstone range from 0 to 5 percent. Soft lignite fragments range from a trace to about 15 percent. Texture is mostly loam, silt loam, sandy clay loam, clay loam, silty clay loam, clay or silty clay with less than 15 percent material coarser than very fine sand.
The A horizon has hue of 10YR or 7.5YR, value of 4 or 5, and chroma of 2 through 6. Fragments or masses of darker or lighter materials range from none to few.
The C horizon has hue of 10YR or 7.5YR, value of 4 through 6, and chroma of 2 through 6. Masses or mottles of gray, red or brown from the overburden material range from none to common. It has masses or thin layers of varying textures.
COMPETING SERIES: There are no competing series in the same family. Similar soils are the Diswood, Distell, Gibboncreek, Grayrock and Thermo series. Distell, Diswood, and Thermo soils have fragments of diagnostic horizons within the control section. In addition, the Distell soils have fine-loamy control sections and the Diswood and Thermo soils have fine control sections and are in the Udic moisture regime. The Gibbonscreek soils have fine-loamy control sections and an EC of 1 to 5 mmhos/cm and exchangeable sodium percentage of more than 5 throughout. Grayrock soils are in a Udic moisture regime.
GEOGRAPHIC SETTING: Bigbrown soils are on gently sloping to moderately steep slopes. They are on mine spoil areas where lignite strip mining operations have taken place. Slope gradients range from 1 to about 15 percent and are simple to complex, depending on how much the spoil piles have been smoothed or reclaimed. Reclaimed areas have slopes that are gentle and fairly uniform over large tracts. The mean annual temperature ranges from about 64 degrees to 70 degrees F. Average annual precipitation ranges from 32 to 42 inches, and Thornthwaite P-E indices range from 46 to 66. Geology of the area is Wilcox formation of Tertiary age.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Axtell, Crockett, Edge, Gasil, Gredge, Lufkin, Nimrod, Padina, Rader, Silstid and Wilson soils. All of these soils have argillic horizons and are on nearby undisturbed areas.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; slowly permeable after a few years settlement, moderately slow to rapid permeability for a few years after deposition.
USE AND VEGETATION: Most areas are in pasture. Some areas are idle and are in various stages of reclamation and plant succession. Smoothed areas have been fertilized and planted to bermudagrass, kleingrass, and arrowleaf clover.
DISTRIBUTION AND EXTENT: The Claypan area of east central Texas. The series is now of minor extent but there is expected to be an increase in acreage as lignite strip mining continues.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Freestone County, Texas; 1986. The name is from Big Brown Creek which drains the type location.
REMARKS: Bigbrown soils have previously been mapped a miscellaneous land type: mined area. The mining near the type location began about 1972 and the type location was mined in 1975. The shale and lignite fragments in fresh overburden materials usually breaks down when weathered for only a few years.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 8 inches.
Parent materials - consist of lignite strip mine unoxidized overburden.
ADDITIONAL DATA: PhD Thesis - Frank Michael Hons, TAMU, 1978; and MS Thesis - Eddie D. Bearden, TAMU, 1984.