LOCATION CLEARFORK          TX

CLEARFORK SERIES

The Clearfork series consists of very deep, well drained, moderately slowly permeable soils that formed in calcareous loamy and clayey alluvium. These soils are on nearly level flood plains. Slopes are 0 to 1 percent.

TAXONOMIC CLASS: Fine-silty, mixed, active, thermic Cumulic Haplustolls

TYPICAL PEDON: Clearfork silty clay loam--pastureland. (Colors are for dry soil unless otherwise stated.)

A1--0 to 4 inches; reddish brown (5YR 4/3) silty clay loam, dark reddish brown (5YR 3/3) moist; moderate coarse subangular blocky structure; very hard, very firm, very sticky and plastic; many fine roots; many fine pores; many worm casts; dry weather cracks about 1 cm wide; strongly effervescent; moderately alkaline; clear smooth boundary. (4 to 10 inches thick)

A2--4 to 17 inches; reddish brown (5YR 5/3) silty clay loam, dark reddish brown (5YR 3/3) moist; moderate fine and medium subangular blocky structure; very hard, very firm, very sticky and plastic; many fine roots; common pores; common worm casts; dry weather cracks 5 to 8 mm wide; few threads and films of calcium carbonate; strongly effervescent; moderately alkaline; clear smooth boundary. (6 to 15 inches thick)

A3--17 to 28 inches; dark reddish gray (5YR 4/2) silty clay loam; dark reddish brown (5YR 3/2) moist; moderate medium and coarse subangular blocky structure; very hard, very firm, very sticky and plastic; common fine roots; common fine pores; few worm casts; few films and threads of calcium carbonate; strongly effervescent; moderately alkaline; clear smooth boundary. (6 to 18 inches thick)

Bw1--28 to 59 inches; reddish brown (5YR 4/4) silty clay loam, dark reddish brown (5YR 3/4) moist; moderate medium subangular blocky structure; hard, firm, sticky and plastic; common fine roots; common fine pores; common worm casts; few films and threads of calcium carbonate; few thin lenses of silt loam; violently effervescent; moderately alkaline; clear smooth boundary. (8 to 35 inches thick)

Bw2--59 to 76 inches; reddish brown (5YR 5/4) silty clay loam, reddish brown (5YR 4/4) moist; weak fine and medium subangular blocky structure; hard, firm, sticky and plastic; common fine and medium roots; many fine tubular pores; few worm casts; few broken shell fragments; few threads of calcium carbonate; few thin discontinuous lenses of silt loam; violently effervescent; moderately alkaline; clear smooth boundary. (6 to 30 inches thick)

Bw3--76 to 83 inches; reddish brown (5YR 5/4) silty clay loam; reddish brown (5YR 4/4) moist; weak fine subangular blocky structure; hard, firm, sticky and plastic; few fine roots; many fine tubular pores; few worm casts; few films and threads of calcium carbonate; violently effervescent; moderately alkaline.

TYPE LOCATION: Stephens County, Texas; 12.9 miles northwest of U.S. Highway 180 in Breckenridge on U.S. Highway 183; 4.6 miles west on county road; 0.8 miles north-northeast on a range trail; 30 feet south in range. Latitude 32 degrees, 54 feet, 2 inches N; Longitude 99 degrees, 4 feet, 45 inches W.

RANGE IN CHARACTERISTICS: The mollic epipedon is 20 to about 40 inches thick. COLE ranges from 0.035 to 0.065. Dry weather cracks less than 1 cm wide extend from the surface to a depth of about 20 inches. Total clay content of the control section averages from 29 to 44 percent and silicate clay is 28 to 35 percent. Reaction is slightly or moderately alkaline throughout the solum.

The A horizon has hue of 5YR, 7.5YR, or 10YR value of 3 to 5, and chroma of 2 or 3. Texture is clay loam, silty clay loam or silty clay. Calcium carbonate equivalent is 0 to 13 percent.

The Bw or Bk horizons have hue of 5YR, 7.5YR, or 10YR value of 3 to 6, and chroma of 4 to 6. Texture is clay loam, silty clay loam, silty clay. Most pedons have thin, discontinuous strata or lenses of loam or silt loam. It also commonly contains few to common films, threads, very fine masses and concretions of calcium carbonate. Calcium carbonate equivalent is 5 to 15 percent.

COMPETING SERIES: These are the Nipsum (TX) and Westfork (TX) series. Closely similar soils include the Asa, Bosque, Clairemont, Deleon, Frio, Gageby, Mangum, Miller, and Port series. Nipsum soils are dry in the control section for longer periods of time and do not have stratification below a depth of 50 cm. Westfork soils are slightly acid to slightly alkaline in the surface layer, and do not have stratification below a depth of 50 cm. Asa soils are hyperthermic, Bosque and Gageby soils have fine-loamy control sections, and Clairemont soils have ochric epipedons. Frio soils do not have colors with hue redder than 7.5YR and have smectitic mineralogy. Deleon, Mangum, and Miller soils have vertic properties. Port soils are superactive CEC activity class.

GEOGRAPHIC SETTING: Clearfork soils are on flood plains that drain areas having soils formed from red beds. Slopes are dominantly less than 1 percent. The soils formed in calcareous loamy and clayey Holocene alluvium. Mean annual precipitation ranges from 24 to 30 inches and mean annual temperatures ranges from 62 to 65 degrees F. Frost free days range from 214 to 225 days and elevation ranges from 1,000 to 1,300 feet. Thornthwaite P-E indices range from 34 to 44.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Clairemont and Frio soils and the Leeray, Owens, Throck and Thurber soils. Clairemont and Frio soils are on flood plains. Leeray, Owens, Throck and Thurber soils are on adjacent uplands. Leeray soils have intersecting slickensides. Owens and Throck soils are underlain with shale that has clay texture and do not have a mollic epipedon. Thurber soils have an argillic horizon.

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately slow. These soils are subject to rare to occassional flooding for very brief to brief periods. Runoff is negligible.

USE AND VEGETATION: Used mostly for rangeland. Native vegetation consists of Texas wintergrass, vine mesquite, Canada wildrye, little barley, buffalograss, and tall dropseed. Woody vegetation is mesquite, scattered live oak, and elm. Some areas are cultivated. Wheat, grain sorghum, and cotton are the main crops.

DISTRIBUTION AND EXTENT: Central Texas in the Texas North Central Prairies and Rolling Limestone Prairie. This series is of moderate extent.

MLRA OFFICE RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Soil Survey of Shackleford County, Texas; 1985.

REMARKS: This soil was previously in the Miller, Mangum or Nipsum series. Local tests show COLE of 0.04 to 0.05. It was changed from a fine to fine silty particle size class and from superactive to active based on NSSL and TAMU laboratory data.

Diagnostic horizons and features recognized in this pedon are:

Mollic epipedon - the zone from the surface to a depth of about 28 inches. (A1, A2, A3 horizons).

Cumulic feature - have a mollic epipedon about 28 inches thick and have irregular decrease in organic matter.

Cambic horizons - 28 to 83 inches. (Bw1, Bw2 and Bw3 horizons)

ADDITIONAL DATA: NSSL Sample Nos. 84P 203-208 of pedon S83TX-429-1(1-6) from the type location. TAMU sample nos. S86TX503-1-1, S86TX429-1-1 and S86TX417-1.