LOCATION PURVES TX+OK
Established Series
Rev. CLN-ACT-RM
08/2018
PURVES SERIES
The Purves series consists of shallow, well drained, moderately slowly permeable soils that formed in interbedded limestone and marl. These soils are on gently sloping to steep upland divides with plane to convex surfaces. Slopes are mainly 1 to 5 percent, but range from 1 to 40 percent.
TAXONOMIC CLASS: Clayey, smectitic, thermic Lithic Calciustolls
TYPICAL PEDON: Purves clay--pasture. (Colors are for dry soil unless otherwise stated.)
A--0 to 20 cm (0 to 8 in); very dark grayish brown (10YR 3/2) clay, very dark brown (10YR 2/2) moist; strong very fine subangular blocky and granular structure; very hard, firm; many fine roots; calcareous; moderately alkaline; gradual smooth boundary. (15 to 30 [6 to 12 in] thick)
Ak--20 to 30 cm (8 to 12 in); brown (10YR 4/3) clay, dark brown (10YR 3/3) moist; strong very fine subangular blocky and granular structure; hard, firm; common fine roots; few to common concretions and soft masses of calcium carbonate; calcareous; moderately alkaline; clear smooth boundary. (5 to 20 cm [2 to 8 in] thick)
Bk--30 to 36 cm (12 to 14 in); brown (10YR 5/3) very gravelly clay dark brown (10YR 3/3) moist; strong fine granular structure; hard, firm; contains about 70 percent fragments of limestone 3 to 15 cm (1 to 6 in) across the long axis; fragments have pendants and coatings of calcium carbonate 3 to 10 mm thick; many fine concretions; calcareous; moderately alkaline; abrupt smooth boundary. (0 to 13 cm [0 to 5 in] thick)
R--36 to 51 cm (14 to 20 in); indurated limestone, with a hardness by Moh's scale of 3 or more; contains a few fractures.
TYPE LOCATION: Erath County, Texas; from the center of Purves, Texas, 0.5 mile southeast of Farm Road 219; 0.27 mile northeast on private road, and 120 ft northwest of road in native grass pasture.
USGS topographic quadrangle:
Latitude 32 degrees, 00 minutes 13 seconds N;
Longitude 98 degrees, 15 minutes 33 seconds W.
RANGE IN CHARACTERISTICS:
Solum thickness ranges from 20 to 51 cm (8 to 20 in).
Fragments of limestone that are 2 mm to 25 cm (10 in) across the long axis range from none to 35 percent by volume of the material above the bedrock.
Secondary carbonates occur as concretions and soft masses and as coatings and pendants on fragments. Calcium carbonate equivalent ranges from 5 to 45 percent, but averages 15 to 40 percent in the AK and BK horizons.
A horizon
Hue: 10YR or 7.5YR
Value: 3 to 5 dry and 2 or 3 moist
Chroma: 1 to 3
Texture: clay loam, silty clay loam, silty clay, or clay with silicate clay content ranging from 35 to 55 percent, and includes textures with gravelly, cobbly, and stony textural class modifiers.
Bk horizon
Hue: 10YR or 7.5YR
Value: 3 to 5 dry and 2 or 3 moist
Chroma: 1 to 3
Texture: clay loam, silty clay loam, silty clay, or clay with silicate clay content ranging from 35 to 55 percent, and includes textures with gravelly, cobbly, and stony textural class modifiers.
R layer
Indurated limestone, with a hardness by Moh's scale of 3 or more; contains a few fractures.
COMPETING SERIES: There are no competing series in the same family. Similar soils are the
Eckrant,
Ector,
Harper,
Kavett,
Lueders,
Maloterre,
Mereta,
Stephen,
Talpa, and
Tarrant series.
Eckrant,
Ector,
Lueders, and
Tarrant soils: have skeletal control sections.
Harper soils: have vertic properties and are noncalcareous.
Kavett and
Mereta soils: have petrocalcic horizons.
Maloterre and
Talpa soils: are in loamy families.
Stephen soils: have a paralithic contact.
GEOGRAPHIC SETTING:
Parent material: interbedded hard limestones and calcareous marls
Landscape: Dissected plateaus
Landform: backslopes of ridges
Slope: commonly 1 to 5 percent, but the range is 1 to 40 percent
Mean annual air temperature: 17.8 to 20.0 degrees C (64 to 68 degrees F)
Mean annual precipitation: 686 to 940 mm (27 to 37 in)
Frost-free period: 210 to 240 days
Elevation: 122 to 548.6 m (400 to 1800 ft)
Thornthwaite P-E Index: 40 to 60
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Denton,
Dugout,
Eckrant,
Maloterre,
San Saba, and
Tarrant series.
Denton and
San Saba soils: have sola thicker than 51 cm (20 in) and are in lower, less sloping positions.
Eckrant,
Maloterre,
Tarrant, and
Dugout soils: are on similar or slightly higher positions, in addition, Dugout soils have loamy control sections and lack dark colored A horizons.
DRAINAGE AND PERMEABILITY:
Drainage class: Well.
Permeability class: Moderately slow.
Runoff: low on slopes less than 1 percent, medium on slopes of 1 to 5, high on slopes of 5 to 20, and very high on slopes greater than 20 percent
USE AND VEGETATION: Used mainly as rangeland, with some areas cultivated to small grains. Vegetation in rangeland is predominantly mid grasses, with some live oak and mesquite trees.
DISTRIBUTION AND EXTENT: Mainly in the Grand Prairie, Edwards Plateau, Texas North-Central Prairies, and Texas Blackland Prairie of Central Texas. The soil is extensive.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Travis County, Texas; 1969.
REMARKS: Purves soils were formerly classified as a shallow phase of the Denton series.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 36 cm (0 to 14 in) (A, AK, and BK horizons)
Calcic horizon: 30 to 36 cm (12 to 14 in) (AK and BK horizons)
Lithic feature: 36 cm (14 in)
ADDITIONAL DATA: None
TAXONOMIC VERSION: Keys to Soil Taxonomy, Twelfth Edition, 2014
National Cooperative Soil Survey
U.S.A.