LOCATION PUERTA                  TX

Established Series
Rev. ERB-AJT-JCW
01/2011

PUERTA SERIES

The Puerta series consists of shallow, well drained, moderately slowly permeable soils formed in gravelly, cobbly, or stony clayey materials over igneous bedrock. These strongly sloping to steep soils occur on igneous mountains. Slopes range from about 8 to 45 percent.

TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Alfic Lithic Argiustolls

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

A--0 to 5 inches; dark grayish brown (10YR 4/2) very gravelly silt loam, very dark brown (10YR 2/2) moist; strong fine granular structure; soft, friable; many fine roots; 40 percent by volume of igneous rock fragments comprising about 30 percent gravel and 10 percent cobbles; neutral; abrupt smooth boundary. (4 to 6 inches thick)

E--5 to 9 inches; light brownish gray (10YR 6/2) very gravelly loam, dark grayish brown (10YR 4/2) moist; weak fine subangular blocky structure; slightly hard, friable; many fine roots; coarse fragments as above; moderately acid; clear irregular boundary. (1 to 7 inches thick)

Bt--9 to 18 inches; brown (7.5YR 5/2) very gravelly clay, brown (7.5YR 4/2) moist; strong medium blocky structure; hard, firm; plastic, sticky; few medium roots; few distinct clay films; 50 percent by volume of coarse igneous rock fragments comprising about 35 percent gravel, and 15 percent cobbles; strongly acid; abrupt irregular boundary. (5 to 15 inches thick)

R--18 to 30 inches; fractured grayish igneous bedrock with seams in rock filed with clay as above.

TYPE LOCATION: Jeff Davis County, Texas; 11.5 miles west of the McDonald Observatory on Texas Highway 118, south along ranch road in Loghouse Canyon 3.25 miles.

RANGE IN CHARACTERISTICS:

Soil moisture: Typic ustic moisture regime.

Depth to igneous bedrock: 11 to 20 inches

Rock fragments; 35 to 80 percent coarse fragments consisting of 20 to 50 percent gravel, 5 to 35 percent cobbles and 0 to 25 percent stones. Some pedons have stones 10 to 24 inches in diameter.

A horizon
Hue: 7.5YR, 10YR
Value: 3 to 5, dry or moist
Chroma: 2 or 3, dry or moist
Texture: loam, silt loam, or sandy loam.

E horizon
Hue: 5YR to 10YR
Value: 4 to 7, dry or moist
Chroma: 2 or 3, dry or moist
Texture: loam, sandy loam

Bt horizon
Hue: 5YR through 10YR
Value: 4 through 6, dry or moist
Chroma: 2 through 4, dry or moist
Texture: clay
Clay content: 50 to 70 percent
In some pedons the Bt horizon is divided into Bt1 and Bt2.

The R layer is extrusive igneous rock mostly of rhyolite and trachyte

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Puerta soils are on hills and mountains formed by the dissection of a vast area of igneous rocks. These soils have developed in a shallow stony mantle over igneous bedrock. Slopes are mostly 8 to 45 percent. Elevation is 5,575 and 7,800 feet. Annual rainfall is from 18 to 26 inches. The mean air temperature is about 55 degrees F. Frost free period is 160 to 200 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Madrone series and Loghouse series. Loghouse soils have a sandy-skeletal control section.

DRAINAGE AND PERMEABILITY: Well drained; moderate to rapid runoff; moderately slow permeability.

USE AND VEGETATION: Used mainly as native range. Vegetation is dominantly pines, oaks, and junipers with some grasses such as pinion ricegrass, purple muhly, plains lovegrass, and little bluestem.

DISTRIBUTION AND EXTENT: At the higher elevation of the Davis Mountains and Chisos Mountains in southwest Texas. The series is inextensive (probably about 10,000 acres.) MLRA 42.

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

SERIES ESTABLISHED: Jeff Davis County, Texas; 1971.

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

Mollic epipedon - the zone from 0 to 5 inches. (A horizon)

Albic horizon - the zone from 5 to 9 inches. (E horizon)

Argillic horizon - the zone from 9 to 18 inches. (Bt horizon)

Lithic contact - igneous bedrock at 18 inches. (R horizon)

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

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

ADDITIONAL DATA: Lincoln Soil Survey Laboratory data are available (66L159, 66L160). Organic carbon content of the A horizon is 3.5 percent.

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National Cooperative Soil Survey
U.S.A.