LOCATION MARISCAL TXEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, carbonatic, hyperthermic Lithic Ustic Torriorthents
TYPICAL PEDON: Mariscal very channery clay loam--rangeland. (Colors are for dry soils unless otherwise stated.)
A--0 to 5 cm (0 to 2 inches); pale brown (10YR 6/3) very channery loam, brown (10YR 4/3) moist; moderate fine and medium granular structure; slightly hard, friable, slightly sticky and nonplastic; common fine and medium roots; 60 percent limestone channers 1 to 6 inches across 1/4 to 1 inch thick and 1 to 4 inches wide; violently effervescent; moderately alkaline; abrupt smooth boundary. (3 to 25 cm, 1 to 10 inches thick.)
Bk--5 to 13 cm (2 to 5 inches); pale brown (10YR 6/3) very channery loam, brown (10YR 5/3) moist; moderate medium granular structure; slightly hard, friable, slightly sticky and nonplastic; few fine roots; 60 percent flat limestone channers; channers coated with calcium carbonate on the lower side; violently effervescent; moderately alkaline; abrupt smooth boundary. (5 to 25 cm, 2 to 10 inches thick)
Rk--13 to 25 cm (5 to 10 inches); platy fractured limestone that has secondary coatings of calcium carbonate in seams and between plates; gradual smooth boundary. (0 to 30 cm, 0 to 12 inches thick)
R--25 to 102 cm (10 to 40 inches; interbedded limestone bedrock 30 to 61 cm (1 to 2 feet) thick with layers of marl (3 to 25 cm, 1 to 10 inches) thick.
TYPE LOCATION: Brewster County, Texas; from Rio Grande Village in Big Bend National Park; 4.5 miles west on paved park road; 1.45 miles south on Hot Springs Road; 280 feet east in rangeland. Rio Grande Village USGS 7.5 minute topographic quadrangle; Latitude: 29 degrees, 10 minutes, 25 seconds North; Longitude: 103 degrees, 00 minutes, 13 seconds West; NAD27
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 5.0 degrees C (41 degrees F). Intermittently moist in some part of the soil moisture control section during June to 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. Ustic aridic soil moisture regime.
Mean annual soil temperature: 22.0 to 25.6 degrees C (72 to 78 degrees F)
Depth to bedrock: mainly 10 to 30 cm, but ranging up to 50 cm (4 to 12 inches, but ranging up to 20 inches).
Particle size control section (weighted average):
Calcium carbonate equivalent: 40 to 70 percent in the fine earth fraction and ranges to 80 percent when less than 20 millimeter fragments are included.
Rock fragments: 35 to 85 percent channers or flagstones.
The A, Bk and BCk horizons:
Hue: 10YR
Value: 5 to 7,
Chroma: 2 to 4.
Texture of the fine earth fraction: sandy loam, loam or silt loam
Clay content: 10 to 30 percent.
Calcium carbonate coats on rock fragments: faint discontinuous films to pendants up to 2 inches thick.
R layer:
fractured limestone bedrock that contains from 10 to 50 percent interbedded chalky, or marly materials (6 mm to 25 cm (1/4 to 10 inches) thick.
COMPETING SERIES: No other series is in the same family. Similar soils are the
Blackgap (P TX),
Langtry (TX),
Lozier (TX), and
Terlingua (TX) series. None of these soils is derived from or underlain by flaggy or channery limestone bedrock.
Langtry soils have mollic epipedons.
Lozier soils are underlain by thick-bedded limestone bedrock, and do not have flags or channers as rock fragments in the control section.
Terlingua soils are underlain by basalt bedrock and have mixed mineralogy.
GEOGRAPHIC SETTING: Parent material: residuum and colluvium weathered from flaggy limestone interbedded with chalk and marl (Cretaceous Boquillas formation).
Landform: hillslopes and mountains.
Slope: 1 to 60 percent
Mean annual air temperature: 20.0 to 22.2 degrees C (68 to 72 degrees F)
Mean annual precipitation: 25 to 33 cm (10 to 13 inches).
Precipitation pattern: Most rainfall occurs as afternoon thunderstorms during the summer months. Precipitation during the months of January, February, and March is less than 13 percent of the total.
Frost free period: 240 to 280 days
Elevation: 400 to 1355 meters (1300 to 4450 feet).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Sanderson,
Seferino,
Stillwell,
Strawhouse,
Terlingua, and
Upton series.
Sanderson, Seferino, and Stillwell soils are very deep, and occur within valleys and small channels.
Seferino soils contain less than 35 percent rock fragments.
Terlingua soils are underlain by igneous sills intruded within these limestones and have mixed mineralogy.
Strawhouse and Upton soils are on gravelly pediments and have petrocalcic horizons.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate above a very slowly permeable limestone bedrock. Runoff is 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 rangeland. Vegetation physiognomy is desert shrubland. Dominant woody plants are creosotebush, lechuguilla, feather dalea, yucca, catclaw acacia, and whitethorn acacia. Grasses include chino grama, black grama, fluffgrass, and threeawns.
DISTRIBUTION AND EXTENT: The Southern Edwards Plateau (MLRA 81D) and Trans Pecos (MLRA 42) of Texas. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Val Verde County, Texas; 1980.
REMARKS: Soil temperature regime classification changed from thermic to hyperthermic based on the summary of a 6-year soil temperature study in Far West Texas. Taxonomic class and moisture regime classification changed from typic aridic to ustic aridic.
Classification change from Lithic Calciorthids to Lithic Torriorthents based on observations that the majority of pedons do not meet thickness requirements for a calcic horizon.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: 0 to 13 cm (0 to 5 inches); A horizon
Lithic contact: 25 cm (10 inches); the upper boundary the R layer
ADDITIONAL DATA: Data from TAMU Soil Characterization Laboratory are available from a site in Brewster County, Texas, Main Part, survey area. (S90TX-043-005).
TAXONOMIC VERSION: Keys to Soil Taxonomy, Tenth Edition, 2006