LOCATION THROCK TX

Established Series
Rev. ACT:WJG
11/2013

THROCK SERIES

The Throck series consists of soils that are moderately deep and deep over claystone bedrock or dense clay. They are calcareous, well drained, slowly permeable soils that formed in slope alluvium and/or residuum derived from claystone and siltstone. They occur on gently sloping to steep footslopes and back slopes of ridges. Slopes range from 1 to 30 percent. Mean annual precipitation is about 686 mm (27 in) and the mean annual air temperature is about 17.8 degrees C (64 degrees F).

TAXONOMIC CLASS: Fine, mixed, active, thermic Vertic Haplustepts

TYPICAL PEDON: Throck clay--rangeland. (Colors are for dry soil unless otherwise stated.)

A--0 to 10 cm (0 to 4 in); dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; moderate fine and medium granular structure; hard, firm; many fine roots; few worm casts; strongly effervescent; moderately alkaline; clear smooth boundary. Thickness is 8 to 23 cm (3 to 9 in)

Bw--10 to 28 cm (4 to 11 in); brown (10YR 5/3) clay, brown (10YR 4/3) moist; weak coarse subangular blocky structure parting to moderate medium granular structure; hard, firm; many fine roots; few very fine pores; few worm casts; few fine iron-manganese concretions; few very fine masses of calcium carbonate in lower 2 inches; strongly effervescent; moderately alkaline; clear wavy boundary. Thickness is 13 to 30 cm (5 to 12 in)

Bk1--28 to 51 cm (11 to 20 in); brown (10YR 5/3) silty clay, brown (10YR 4/3) moist; moderate coarse and medium angular blocky structure; very hard, firm; common fine roots; few fine pores; few worm casts; common pressure faces on faces of peds; few intersecting slickensides; few fine iron-manganese concretions; 7 percent very fine to medium masses of calcium carbonate; violently effervescent; strongly alkaline; gradual smooth boundary. Thickness is 20 to 51 cm (8 to 20 in)

Bk2--51 to 86 cm (20 to 34 in); brown (10YR 5/3) silty clay, brown (10YR 4/3) moist; thick, wedge-shaped peds tilted at 15 to 45 degrees from horizontal parting to moderate coarse angular blocky structure; extremely hard, very firm; few and very fine roots; common fine pores; few worm casts; few grayish brown (10YR 5/2) stains on faces of peds; common fine iron-manganese concretions; about 3 percent very fine and fine masses and concretions of calcium carbonate; violently effervescent; moderately alkaline; gradual smooth boundary. Thickness is 0 to 30 cm (0 to 12 in)

BC--86 to 102 cm (34 to 40 in); pale brown (10YR 6/3) silty clay, brown (10YR 5/3) moist; weak, thick, wedge-shaped peds tilted at 15 to 45 degrees from horizontal parting to weak coarse angular blocky structure; few fine roots; few very fine pores; common fine iron-manganese concretions; few very fine threads and crystals of salt and gypsum on faces of peds; few very fine masses and concretions of calcium carbonate; violently effervescent; moderately alkaline; clear wavy boundary. Thickness is 0 to 48 cm (0 to 19 in)

Cd1--102 to 157 cm (40 to 62 in); grayish brown (2.5Y 5/2) interbedded fractured noncemented siltstone and claystone bedrock, dark grayish brown (2.5Y 4/2) moist; weak thin to thick platy rock structure that has vertical fractures that roots can enter 2.5 to 10 cm apart and weak angular blocky structure; very fine cross-bedding planes with light brownish gray (2.5Y 6/2) mottles; few course to fine roots in cracks; many iron-manganese concentrations on surfaces along cracks; few very fine gypsum and salt crystals on surfaces along cracks; few very fine threads and films of calcium carbonate on surfaces along cracks; noncalcareous in matrix and strongly effervescent on surfaces along cracks; moderately alkaline. Thickness is 20 to 102 cm (8 to 40 in)

Cd2--157 to 203 cm (62 to 80 in); light brownish gray (10YR 6/2) noncemented claystone bedrock; 25 percent yellowish brown (10YR 5/6), 15 percent weak red (2.5YR 4/2), and 10 percent yellow (10YR 7/6) mottles; cracks that roots can enter is greater than 10 centimeter apart; few iron manganese stains on surfaces along cracks; few very fine carbonate masses in cracks; few gypsum crystals in cracks; few salt masses in cracks; non calcareous; slightly alkaline; clear wavy boundary.

TYPE LOCATION: Shackelford County, Texas; from the intersection of U.S. Highway 283 and U.S. Highway 180 in Albany; 3.5 miles west on U.S. Highway 180, 0.35 mile northwest on Private road 2310, 0.25 mile north on a Newell Ranch Road, 500 feet northwest in rangeland about 180 feet northeast of stock tank dam. USGS topographic quadrangle: Albany, TX; Latitude: 32 degrees, 43 minutes, 10.3 seconds N; Longitude: 99 degrees, 21 minutes, 58.4 seconds W. Datum: WGS84; UTM Easting: 465681.00 m, UTM Northing: 3620255.00 m, UTM Zone 14 .

RANGE IN CHARACTERISTICS:
Depth to densic bedrock: 76 to 152 cm (30 to 60 in)
Surface Fragments: 0 to 5 percent stones
Effervesence: Most pedons are calcareous throughout

Particle-size control section (weighted average)
Clay content: 35 to 60 percent

A horizon:
Hue: 7.5YR to 2.5Y
Value: 4 or 5
Chroma: 2 to 4; the A horizon is either too thin or too low in organic matter or both to qualify as a mollic epipedon when moist values are 3.
Texture: clay loam, silty clay loam, silty clay or clay
Clay Content: 30 to 60 percent
Rock fragments: 1 to 15 percent limestone in most pedons, but ranges to 30 percent
Reaction: slightly alkaline or moderately alkaline

Bw or By horizons:
Hue: 7.5 YR to 2.5Y
Value: 4 to 6
Chroma: 2 to 4
Texture: silty clay loam, silty clay or clay
Clay content: 35 to 60 percent
Rock fragments: few to 30 percent limestone and are mostly less than 8 cm (3 in) in diameter
Calcium carbonate equivalent: 4 to 15 percent
Electrical conductivity: 0 to 2 mmhos/cm
Gypsum: 0 to 2 percent
Sodium adsorption ratio: 1 to 6
Reaction: slightly alkaline or moderately alkaline

Bk or Bky horizons:
Hue: 7.5 YR to 2.5Y
Value: 5 to 7
Chroma: 2 to 7
Texture: silty clay loam, silty clay or clay
Clay content: 40 to 60 percent
Calcium carbonate equivalent: 15 to 40 percent
Electrical conductivity: 1 to 8 mmhos/cm
Gypsum: 0 to 5 percent
Sodium adsorption ratio: 2 to 15
Reaction: moderately alkaline or strongly alkaline

BC horizon (where present)
Hue: 7.5 YR to 2.5Y
Value: 5 to 7
Chroma: 2 to 7
Texture: silty clay loam, silty clay or clay
Clay content: 40 to 60 percent
Calcium carbonate equivalent: 15 to 40 percent
Electrical conductivity: 1 to 8 mmhos/cm
Gypsum: 0 to 5 percent
Sodium adsorption ratio: 2 to 15
Reaction: moderately alkaline or strongly alkaline

Cd horizons:
Color: shades of gray, olive, yellow or brown; layers of reddish claystone, occur in a few pedons.
Texture: noncemented claystone or siltstone bedrock, or massive dense clay or silty clay, but ranges to clay loam, sandy clay loam, or loam in some pedons; Interbedded strata of limestone 5 to 61 cm (2 to 24 in) in thickness occur in most pedons at depths of 102 to 203 cm (40 to 80 in).
Concentrations: Some pedons contain accumulations of carbonates and gypsum in fractures.
Reaction: slightly alkaline or moderately alkaline

COMPETING SERIES: These are the Tilvern and Mangum series in the same family. Similar soils are the Altoga, Ellis, Owens, and Vernon series.
Altoga soils: have carbonatic mineralogy
Ellis soils: have smectitic mineralogy
Mangum soils: have a hue of 5YR or redder in the B horizon and do not have claystone bedrock layer within 152 cm (60 inches)
Owens soils: do not have calcic horizons and are less than 76 cm (30 inches) deep to claystone bedrock.
Tilvern and Vernon soils: have hue of 5YR or redder and are derived from redbed sediments of Permian age.

GEOGRAPHIC SETTING:
Parent material: slope alluvium and/or residuum derived from claystone and siltstone interbedded with limestone
Landscape: hills
Landform: backslopes and footslopes of ridges
Slope: dominantly 1 to 5 percent, but ranges up to 30 percent
Mean annual precipitation: 660 to 787 mm (26 to 31 in)
Thornthwaite annul P-E index: 38 to 44
Mean annual air temperature: 17.2 to 18.9 degrees C (63 to 66 degrees F)
Frost-free period: 210 to 240 days
Elevation: 304.8 to 685.8 meters (1,000 to 2,250 ft)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the similar Owens series and the Hensley, Lindy, Lueders, Mereta, and Speck series.
Hensley, Lueders, and Speck soils: are less than 52 cm (20 in) deep to limestone bedrock.
Lindy soils: are underlain by limestone.
Mereta soils: have a petrocalcic horizon..

DRAINAGE AND PERMEABILITY: Well drained. Permeability is slow. Runoff is high on 1 to 5 percent slopes and very high on slopes greater than 5 percent.

USE AND VEGETATION: Used for rangeland but a few areas are cultivated and planted to small grain. Native grasses are sideoats grama, blue grama, little bluestem, silver bluestem, buffalograss, and Texas wintergrass.

DISTRIBUTION AND EXTENT: North-central Texas, mainly in the Rolling Limestone Prairie (MLRA 78A), Central Rolling Red Plains, Eastern Part (MLRA 78C) and Texas North Central Prairies (MLRA 80B). The series is extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Baylor County, Texas; 1971.

REMARKS: Classification change from Typic Ustochrepts to Vertic Ustochrepts based on laboratory data from Stephens, Throckmorton and Shackelford Counties. COLE data and slickensides indicate the need for the change.
Classification further updated to Vertic Haplustepts to conform to current taxonomy (Keys to Taxonomy, Eleventh Edition).

Changed to tabular format and included metric values (RFG-11/2013)

Diagnostic horizons and features recognized in this pedon are:
Ochric Epipedon - 0 to 10 cm (0 to 4 in). (A horizon)
Cambic horizon - 10 to 28 cm (4 to 11 in). (Bw horizon)
Calcic horizon - 28 to 51 cm (11 to 20 in). (Bk1 horizon)
Densic material - 102 to 203 cm (40 to 80 in). (Cd1 and Cd2 horizons)
Densic contact - 157 cm (62 in). (Cd2 horizons)

ADDITIONAL DATA; NSSL S80TX-417-001, NSSL S84TX-429-006, and TA&MU S89TX-447-001

Taxanomic version: Keys to Soil Taxonomy, Eleventh Edition, 2010

National Cooperative Soil Survey
U.S.A.