LOCATION GEEFOUR                 TX

Established Series
Rev. JLR
10/2012

GEEFOUR SERIES

The Geefour series consists of very shallow and shallow, well drained, slowly permeable soils formed in residuum over dense noncemented mudstone. These soils are on erosional hillslopes associated with badlands. Slopes range from 3 to 45 percent. The mean annual precipitation is about 11 inches and the mean annual air temperature is about 70 degrees F.

TAXONOMIC CLASS: Clayey, smectitic, calcareous, hyperthermic, shallow Ustic Torriorthents

TYPICAL PEDON: Geefour very gravelly silty clay--rangeland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 2 inches; light brownish gray (2.5Y 6/2) very gravelly silty clay, grayish brown (2.5Y 5/2) moist; moderate medium subangular blocky structure; very hard, very firm; few very fine and fine roots; 45 percent igneous gravel; sllightly effervescent; moderately alkaline; abrupt smooth boundary. (0 to 5 inches thick)

A2--2 to 7 inches; light brownish gray (2.5Y 6/2) clay, grayish brown (2.5Y 5/2) moist; strong fine subangular blocky structure; very hard, very firm; slightly effervescent; moderately alkaline; clear smooth boundary. (4 to 10 inches thick)

Cd--7 to 17 inches; densic noncemented mudstone that has clay texture; massive; extremely hard, extremely firm, brittle; many dark reddish brown (2.5YR 3/4) stains on fracture surfaces; strongly effervescent; moderately alkaline.

TYPE LOCATION: Brewster County, Texas; from the junction of Texas Highway 118 and Texas Highway 170 at Study Butte; 2.1 miles north on Texas Highway 118 to Terlingua Ranch Gate 2; 3.5 miles east on ranch road; and 40 feet south of road in range. USGS Tule Mountain 7.5 minute topographic quadrangle. Located at a latitude of 29 degrees, 21 minutes, 24.86 seconds North, and a longitude of 103 degrees, 29 minutes, 8.35 seconds West; NAD83. UTM coordinates: 646964 m E, 3248752 m N, Zone 13.

RANGE IN CHARACTERISTICS:

Soil moisture: Intermittently moist in some part of the soil moisture control section during July through September. Ustic aridic soil moisture regime.

Mean annual soil temperature: 72 to 78 degrees F.

Depth to shale/mudstone bedrock: 3 to 20 inches

Most areas have a desert pavement of rock fragments of 50 to 80 percent gravel, 10 to 40 percent cobbles, and 0 to 10 percent stones covering 40 to 90 percent of the surface.

A1 horizon (where present)
Hue: 10YR, 2.5Y, 5Y, 7.5YR
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 1 to 4, dry or moist
Texture: clay loam, silty clay loam, silty clay, clay
Clay content: 35 to 50 percent
Rock fragment content: 15 to 45 percent
Effervescence: slight to violent
Reaction: moderately alkaline or strongly alkaline

A2 or BC horizon
Hue: 10YR, 2.5Y, 5Y
Value: 5 to 7 dry, 4 through 6 moist
Chroma: 1 to 4, dry or moist
Texture: clay loam, silty clay loam, silty clay, clay
Clay content: 35 to 50 percent
Rock fragment content: 0 to 15 percent
Effervescence: slight to violent
Reaction: moderately alkaline or strongly alkaline

Cd layer
Bedrock: dense shale/mudstone that slakes in water

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Geefour soils are on erosional hillslopes above desert basin floors at elevations of 1,800 to 4,560 feet. Slope ranges from 1 to 45 percent. These soils formed in shale/mudstone of the Pen, Del Rio, and Javelina formations (Cretaceous), and the Banta Shut-in and similar formations (Tertiary). The mean annual precipitation is 10 to 13 inches, and most precipitation occurs mainly as afternoon thunderstorms during the summer and early fall months. The mean annual air temperature is 68 to 72 degrees F. The frost-free period is 240 to 280 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Castolon, Corazones, and Vicente series. Castolon and Vicente soils are very deep, and occur on the Rio Grande flood plain. Castolon soils have fine-silty control sections. Corazones soils contain than more 35 percent rock fragments in the control section and are on higher, older pediments and fans. Vicente soils have coarse-silty control sections.

DRAINAGE AND PERMEABILITY: Well drained. Slowly permeable soil over very slowly permeable densic material. Runoff is high on 1 to 5 percent slopes, and very high on slopes greater than 5 percent.

USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Vegetation includes scattered creosote bush, mound saltbush, tubercled saltbush, and western honey mesquite. Grasses form a very sparse understory of Chino grama, false grama, tobosa, bush muhly, and burrograss.

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

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

SERIES ESTABLISHED: Big Bend National Park, Texas; 2010

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - the zone from 0 to 7 inches (A horizons)

Densic materials - the zone from 7 to 17 inches (Cd horizon-mudstone material that slakes in water)

Densic contact - the boundary at 7 inches (Cd horizon)

Entisol feature - the absence of diagnostic subsurface horizons

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

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

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National Cooperative Soil Survey
U.S.A.