LOCATION STUDYBUTTE              TX

Established Series
Rev. RAC
10/2012

STUDYBUTTE SERIES

The Studybutte series consists of very shallow and shallow, well drained soils that are moderately rapidly permeable over very slowly permeable bedrock. The soils developed in residuum and colluvium weathered from siliceous igneous bedrock. These soils are on hills and mountains. Slopes range from 2 to 60 percent. The mean annual precipitation is about 11 inches and the mean annual air temperature is about 70 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, nonacid, hyperthermic Lithic Ustic Torriorthents

TYPICAL PEDON: Studybutte very gravelly loam--rangeland. (Colors are for dry soil unless otherwise stated.)

A1--0 to 3 inches; reddish brown (5YR 5/3), very gravelly loam, dark reddish brown (5YR 3/3), moist; weak medium granular structure; friable, hard; common fine roots; 50 percent subangular igneous gravel; noneffervescent; slightly alkaline; clear smooth boundary.

A2--3 to 6 inches; reddish brown (5YR 5/3), extremely gravelly loam, dark reddish brown (5YR 3/3), moist; weak medium granular structure; friable, hard; common fine roots; 70 percent angular igneous gravel; slightly effervescent; slightly alkaline; abrupt irregular boundary.

R--6 inches; indurated igneous bedrock.

TYPE LOCATION: Brewster County, Texas; from the intersection of Texas Highway 118 and Ranch Road 170 in Study Butte, 1.4 miles north on Texas Highway 118 to Terlingua Ranch Gate 2, 0.9 mile northeast, 0.9 mile south and southeast, 2.1 miles northeast, 1.3 miles southeast to end of road, then 1600 feet north-northeast in range. Tule Mountain USGS 7.5 minute topographic quadrangle; Latitude: 29 degrees 21 minutes 55.7 seconds N, Longitude: 103 degrees 27 minutes 24.7 seconds W NAD83; UTM coordinates: 649779 m E, 3249467 m N Zone 13

RANGE IN CHARACTERISTICS:
Soil moisture: Ustic aridic soil moisture regime. Receives precipitation in all months. Driest period is November through April with peak rainfall occurring during May through October.

Mean annual soil temperature: 72 to 78 degrees F.

Depth to igneous bedrock: 4 to 20 inches

Clay content: 5 to 25 percent

Rock fragment content: 35 to 80 percent igneous fragments; 25 to 60 percent gravel; 0 to 20 percent cobbles; 0 to 20 percent stones

Reaction: neutral to moderately alkaline

A horizons
Hue: 5YR, 7.5YR, 10YR
Value: 4 through 6 dry, 3 through 5 moist
Chroma: 2 through 4 dry or moist
Clay content: 5 to 25 percent

R layer
Indurated igneous bedrock
Fractures: less than 4 inches apart
Some pedons have calcium carbonate coats on fracture surfaces

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Studybutte soils from in residuum and colluvium weathered from Tertiary-age siliceous igneous rock. They are on hill slopes and mountainsides with slopes of 10 to 50 percent but range from 2 to 60 percent. The mean annual air temperature is 68 to 76 degrees F. and the mean annual precipitation is 6 to 13 inches. Most precipitation occurs as intense rain during afternoon convectional thunderstorms from June to October. The frost-free period is 240 to 280 days and the elevation is 1,800 to 3,500 feet, ranging up to 4,500 feet.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Corazones and Terlingua series.
Corazones soils have a calcic horizon, are very deep and formed in gravelly alluvium and pedisediment. Terlingua soils occur on similar landforms, but overlie mafic igneous rocks and are calcareous.

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately rapid over very slowly permeable bedrock. Runoff is very low on 2 to 5 percent slopes, low on 5 to 20 percent slopes, and medium on slopes greater than 20 percent.

USE AND VEGETATION: Used for livestock grazing, wildlife habitat and for recreation. Vegetation physiognomy is desert shrubland. Dominant woody plants include lechuguilla, leatherstem, cenizo, catclaw acacia, ocotillo, tasajillo, creosotebush, pricklypear, and dalea species. Grasses are chino grama, sideoats grama, and tanglehead.

DISTRIBUTION AND EXTENT: West Texas. MLRA 42. The series is moderately extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona

SERIES ESTABLISHED: Brewster County, Texas, Main Part, 2008. The name is taken from the community of Study Butte and is pronounced "Stoody-beaut".

REMARKS: Studybutte soils were formerly included in the Lajitas series.

Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - the zone from 0 to 6 inches (A horizons)

Lithic contact - the boundary at 6 inches (R horizon)

Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Eleventh Edition, 2010

Moisture and temperature regime revised for the recorrelation of Brewster County, Texas, Main part, 2/13/2008, CEM

Revised for the correlation of Big Bend National Park, TX, Oct. 2010, CEM

Revised for the correlation of Presidio County, Texas ; Oct, 2012, WWJ

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National Cooperative Soil Survey
U.S.A.