LOCATION SANTAELENA TXTentative Series
TAXONOMIC CLASS: Loamy-skeletal, carbonatic, hyperthermic Lithic Haplocalcids
TYPICAL PEDON: Santaelena very gravelly loam--rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 3 inches; brown (10YR 4/3) very gravelly silt loam, dark brown (10YR 3/3), moist; weak fine subangular blocky structure; 45 percent subangular limestone gravel; violent effervescence; moderately alkaline; gradual smooth boundary. (2 to 6 inches thick)
Bk--3 to 11 inches; brown (10YR 4/3) extremely gravelly silt loam, dark brown (10YR 3/3), moist; weak fine subangular blocky structure; 1 percent fine irregular extremely weakly cemented very pale brown (10YR 8/2), dry, carbonate masses throughout; 70 percent subangular limestone gravel; violent effervescence; moderately alkaline; abrupt smooth boundary. (6 to 13 inches thick)
Rk--11 inches; very pale brown (10YR 8/2) indurated limestone bedrock, light gray (10YR 7/2), moist; strong effervescence; moderately alkaline; secondary calcium carbonate coats in fractures
TYPE LOCATION: Presidio County, Texas. from the junction of US Highway 67 and FM 170 north of Presidio, 12.5 miles north on US Highway 67 to ranch gate, 1.1 miles east on ranch road, 1 mile north on ranch trail, 300 feet south in range. (UTM coordinates: 564,901 meters Easting, 3,292,451 meters Northing; UTM Zone 13 NAD83; Shafter USGS 7.5 minute topographic quadrangle).
RANGE IN CHARACTERISTICS:
Soil moisture: The moisture control section is dry in all parts more than three fourths of the time the soil temperature exceeds 41 degrees F. Intermittently moist in some part of the soil moisture control section during June-September. More than 60 percent of the annual rainfall occurs during that period. The soil does not receive significant amounts of moisture during winter months. Typic aridic soil moisture regime.
Soil temperature: 72 to 78 degrees F
Depth to limestone bedrock: 6 to 20 inches.
Rock fragment content: 35 to 80 percent limestone fragments; 25 to 60 percent gravel; 0 to 20 percent cobbles; 0 to 20 percent stones
Calcium carbonate equivalent: More than 40 percent
The A and Bk horizons
Hue: 7.5YR to 2.5Y
Value: 5 to 8 moist, 4 to 7 dry
Chroma: 2 to 4
Clay content: 15 to 27 percent.
Calcium carbonate: faint discontinuous coats to 1 inch thick pendants on rock fragments
R layer:
Fractures: less than 4 inches apart.
Calcium carbonate coats on fracture surfaces
COMPETING SERIES: These are the Blackgap (P TX) and Iceberg (NV) series. Blackgap soils are dominated by cobbles, and occur in the Southern Edwards Plateau (MLRA 81D). Iceberg soils have less than 18 percent clay in the control section and receive significant winter precipitation, typical of the Mohave Desert (MLRA 30).
GEOGRAPHIC SETTING: These soils are on nearly level mesas or divides to very steep hillslopes; slope gradients range from 0 to 60 percent. The soil formed in residuum and colluvium derived from thick-bedded Cretaceous limestone of the Buda, Santa Elena, Telephone Canyon, Sue Peaks, and Shafter formations. Mean annual precipitation ranges from 10 and 13 inches. Most rainfall falls as afternoon thunderstorms during the summer months. Mean annual air temperature ranges from 68 to 72 degrees F. Frost-free days range from 240 to 280. Elevation is mainly 2000 to 3500 feet, ranging up 4000 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Corazones, Ojinaga (P TX), Strawhouse (P TX), and Stillwell series. Ojinaga and Strawhouse soils are shallow to a petrocalcic horizon and occur on pediments. Corazones and Stillwell soils are very deep and occur on pediments.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate above very slowly permeable bedrock. Runoff is low on slopes less than 1 percent, medium on 1 to 3 percent slopes, high on 3 to 5 percent slopes, and very high on slopes greater than 5 percent.
USE AND VEGETATION: Used as ephemeral rangeland, wildlife habitat, and for recreation. Vegetation physiognomic class is desert shrubland. Dominant woody species are ocotillo, creosotebush, and lechuguilla. Grasses include chino grama, sideoats grama, and tridens. Other characteristic plants are greggs coldenia, leatherstem and candelilla.
DISTRIBUTION AND EXTENT: Southwest Texas. MLRA 42. The series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Phoenix, Arizona
SERIES PROPOSED: Brewster County, Texas; 2004.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: 0 to 3 inches; A horizon
Calcic horizon: 3 to 11 inches; Bk horizon
Lithic contact: at 11 inches; upper boundary of Rk layer
Santaelena soils were formerly included in the Lozier series.