Established Series


The Roughcreek series consists of soils that are shallow to indurated limestone bedrock of Ordovician age. These well drained soils formed in residuum derived from weathering of dolomitic limestone. These gently sloping to steep soils are on summits, shoulders, and back slopes of ridges on dissected plateaus. Slopes are 1 to 40 percent. Mean annual temperature is about 18 degrees C (66 degrees F), and mean annual precipitation is about 686 mm (27 in).

TAXONOMIC CLASS: Clayey-skeletal, smectitic, thermic Lithic Argiustolls

TYPICAL PEDON: Roughcreek very bouldery clay loam--in rangeland. Limestone boulders greater than 600 mm cover 50 percent of the surface. (Colors are for dry soils unless otherwise stated.)

A--0 to 18 cm (0 to 7 in); brown (7.5YR 4/2) very bouldery clay loam, dark brown (7.5YR 3/2) moist; weak fine subangular blocky structure parting to moderate fine granular; very hard, firm; many fine roots; 2 percent chert gravel and 43 percent limestone boulders; neutral; clear smooth boundary. (Thickness of the A horizon is 10 to 25 cm [4 to 10 in])

Bt--18 to 46 cm (7 to 18 in); reddish brown (5YR 4/4) extremely bouldery clay, dark reddish brown (5YR 3/4) moist; moderate fine and medium blocky structure; very hard, very firm; few fine roots; few fine pores; 5 percent fine distinct clay films on all faces of peds; 60 percent limestone boulders and flagstones; neutral; abrupt wavy boundary. (Thickness of the Bt horizon is 15 to 38 cm [6 to 15 in])

R--46 to 71 cm (18 to 28 in); gray (10YR 6/1) coarsely fractured indurated dolomitic limestone; a few soil fines in interstices.

TYPE LOCATION: San Saba County, Texas; From the intersection of Texas Highway 16 and U.S. Highway 190 in San Saba, 2.0 miles west on U.S. Highway 190, 1.4 miles south on private ranch road, and 50 ft east in rangeland.
USGS topographic quadrangle: Algerita, TX
Latitude: 31 degrees, 10 minutes, 47.9 seconds N;
Longitude: 98 degrees, 45 minutes, 12.2 seconds W;
Datum: NAD83.

Solum thickness: 25 to 50 cm (10 to 20 in)
Depth to lithic contact: 25 to 50 cm (10 to 20 in)
Surface rock fragments: Amount-0 to 90 percent by area, kind-limestone, size-2mm to more than 600 mm
Colors: Colors with moist values and chromas of 3 or less, extend to a depth of 18 cm (7 in) or more.
Particle-size control section (weighted average):
Clay content: 40 to 60 percent
A horizon
Hue: 5YR to 10YR
Value: 3 to 5
Chroma: 2 or 3
Texture: Clay loam or clay; very gravelly, very cobbly, very stony, very flaggy, or very bouldery phases
Clay content: 30 to 50 percent
Rock fragments: Amount-30 to 60 percent total by volume, kind-limestone; amount-10 to 20 percent, size-2 to 75 mm; amount-15 to 50 percent, size 76 to more than 600 mm
Effervescence: Noneffervescent
Reaction: Slightly acid to slightly alkaline

Bt horizon
Hue: 2.5YR to 7.5YR
Value: 4 or 5
Chroma: 2 to 6
Texture: Clay; very gravelly, very cobbly, very stony, very flaggy, extremely gravelly, extremely cobbly, extremely stony, extremely flaggy, very bouldery or extremely bouldery phases
Clay content: 40 to 60 percent
Rock fragments: Amount-40 to 80 percent total by volume, kind-limestone; amount-10 to 50 percent, size-2 to 75 mm; amount-15 to 55 percent, size-76 to more than 600 mm
Effervescence: Noneffervescent
Reaction: Slightly acid to slightly alkaline

R layer
Bedrock kind: Dolomitic limestone
Cementation: Strongly cemented or indurated

COMPETING SERIES: This is the Comfort (TX) series. Similar soils include Beaumain (AZ), Eckrant (TX), Harper (TX), Mainstay (TX), Rumple (TX), Speck (TX), and Tarpley (TX).
Comfort soils: have mixed mineralogy.
Beaumain and Mainstay soils: have an aridic moisture regime.
Eckrant soils: do not have an argillic horizon.
Harper, Speck and Tarpley soils: have less than 35 percent rock fragments.
Rumple soils: have a lithic contact 51 a 102 cm (20 to 40 in).

Parent material: The soil formed in residuum weathered from dolomitic limestone. At the type location the bedrock is Ellenberger limestone, of the Ordovician period.
Landscape: Dissected plateaus
Landform: Summits, shoulders, and backslopes of ridges
Slope: 1 to 40 percent
Soil moisture: Typic ustic moisture regime
Precipitation Pattern: The majority of the yearly amount occurs during the fall and spring months. The winter and summer months are normally drier.
Mean annual temperature: 18 to 19 degrees C (64 to 67 degrees F)
Mean annual precipitation: 610 to 762 mm (24 to 30 in)
Frost-free periods: 215 to 235 days
Elevation: 305 to 732 m (1,000 to 2,400 ft)
Thornthwaite P-E indices: 38 to 50

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Campwood (TX), Comfort (TX), Eckrant (TX), Harper (TX), Hensley (TX), Real, and Rumple (TX).
Campwood soils: are very deep alluvial soils that are on stream terraces.
Comfort, Eckrant, Harper, Hensley, Real and Rumple soils: occur on similar landform positions.

Drainage class: Well.
Permeability class: Slow.
Runoff: high on 1 to 5 percent slopes, and very high on 5 to 40 percent slopes.

USE AND VEGETATION: Mainly rangeland and wildlife habitat. The climax plant community is a tall grass savannah with motts of live oak throughout the landscape. The dominant grasses are little bluestem and sideoats grama. Other grasses include yellow Indiangrass, fall witchgrass, wildrye, green sprangletop, meadow dropseed, cane and pinhole bluestem, hairy grama, Texas wintergrass, curly mesquite and buffalograss. Woody plants include live oak, shin oak, evergreen sumac, hackberry, elbowbush, redbud, and white honeysuckle. Forbs, such as orange zexmenia, Engelmann daisy, bundleflower, snout bean, and bushsunflower, are present. The site could potentially deteriorate to a plant population sideoats grama, buffalograss, hairy grama, dropseeds, and the woody plants. If this destructive grazing practice continues, the site will deteriorate to a plant population of Ashe juniper, Texas persimmon, live oak, Texas grama, hairy tridens, curly mesquite, threeawns, prairie coneflower, and broomweed.

DISTRIBUTION AND EXTENT: West-Central Texas; Central Great Plains Winter Wheat and Range Region, LRR-H: 80B-Texas North-Central Prairies. Southwest Plateaus and Plains Range and Cotton Region, LRR-I: MLRA 81B-Edwards Plateau, Central Part; MLRA 81C-Edwards Plateau, Eastern Part. Southwestern Prairies Cotton and Forage Region, LRR-J: MLRA 85-Grand Prairie. This series is extensive with about 210,000 acres.


SERIES ESTABLISHED: San Saba County, Texas; 1980.

REMARKS: Roughcreek series was formerly included in a shallow stony phase of the Crawford series.

Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 18 cm (0 to 7 in) (A horizon)
Argillic horizon: 18 to 46 cm (7 to 18 in) (Bt horizon)
Lithic contact: 46 cm (18 in) soil and limestone interface (top of R layer)

ADDITIONAL DATA: THD Laboratory Data, sample No. 75-127-R.

TAXONOMIC VERSION: Keys to Soil Taxonomy, Twelfth Edition, 2014.

National Cooperative Soil Survey