LOCATION HURDS TX

Established Series
Rev. ERB/RAC/JCW/RLB
12/2010

HURDS SERIES

The Hurds series consists of very deep, well drained, moderately permeable soils that formed in loamy and sandy, gravelly, igneous materials on alluvial fans and terraces in mountain valleys. Slopes range from 3 to about 50 percent.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Aridic Argiustolls

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

A--0 to 10 inches; brown (7.5YR 5/2) gravelly loam, dark brown (7.5YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, friable; slightly sticky; common roots; 30 percent by volume of igneous rock fragments in gravel, cobble and stone size; slightly acid; clear wavy boundary. (3 to 18 inches thick)

Bt1--10 to 17 inches; brown (7.5YR 5/2) very gravelly sandy clay loam, dark brown (7.5YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, friable, sticky, common roots; distinct clay bridging; 45 percent by volume of igneous rock fragments in gravel, cobble and stone size; slightly acid; gradual wavy boundary. (5 to 15 inches thick)

Bt2--17 to 25 inches; reddish brown (5YR 5/4) very gravelly sandy clay loam, dark reddish brown (5YR 3/4) moist; weak fine subangular blocky structure; slightly hard, friable; sticky; common roots; 50 percent by volume of igneous rock fragments of gravel, cobble and stone size; slightly acid; gradual wavy boundary. (5 to 15 inches thick)

Bt3--25 to 40 inches; reddish brown (5YR 5/4) very gravelly sandy loam, dark reddish brown (5YR 3/4) moist; weak fine subangular blocky structure; slightly hard, friable, sticky; few roots; sandy clay loam bands 1/4 to 1/2 inch thick about 3 inches apart; 60 percent by volume of igneous rock fragments of gravel, cobble and stone size; slightly acid; clear wavy boundary. (0 to 20 inches thick)

Bt&C--40 to 60 inches; light reddish brown (5YR 6/4) extremely gravelly loamy sand, reddish brown (5YR 4/4) moist; structureless; hard, friable; sandy loam bands 1/4 to 1/2 inch thick about 2 inches apart; 70 percent by volume of igneous rock fragments of gravel, cobble and stone size; slightly acid.

TYPE LOCATION: Jeff Davis County, Texas; on State Highway 166 due south of Bear Mountain, 1.6 miles east of intersection of county road to Valentine.

RANGE IN CHARACTERISTICS:

Soil moisture: Aridic ustic moisture regime

Thickness of the solum - 34 to 60 inches

Mollic epipedon - 10 to 20 inches thick

Particle size control section -

Clay content: average 18 to 35 percent.

A horizon
Hue: 5YR, 7.5YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3, dry or moist
Texture: sandy loam, loam, or sandy clay loam
Reaction: neutral to slightly acid
Rock fragments: 15 to 50 percent, comprising 15 to 50 percent gravel, and 0 to 15 percent cobbles and stones

Bt horizons
Hue: 5YR or 7.5YR
Value: 4 to 6, dry, 3 or 4 moist
Chroma: 2 to 4, dry or moist
Texture: sandy loam, or sandy clay loam with lamellae of sandy clay loam, clay loam, or sandy clay
Reaction: slightly acid to medium acid
Rock fragments: 15 to 70 percent, comprising 35 to 70 percent gravel, cobbles 2 to 20 percent, and 0 to 20 percent stones

C horizon
Hue: 5YR or 7.5YR
Value: 4 to 6, dry or moist
Chroma: 3 or 4, dry or moist
Texture: loam, sandy loam, or loamy sand
Other features: some pedons have secondary carbonate accumulations
Rock fragments content is similar to the Bt horizon

COMPETING SERIES: These are the Earp (AZ) and Eicks (NM) series
Earp soils are formed in mixed materials of quartz, andesite, granite, and dolomitic limestone. Eicks soils are in the 14 to 16 inches precipitation zone and have hue of 10YR to 2.5Y in Bt horizons.

GEOGRAPHIC SETTING: These soils are on fans and terraces in mountain valleys. Slopes range from 3 to 50 percent. These soils developed in loamy and sandy, gravelly igneous outwash materials. The climate is semiarid to dry subhumid with average annual precipitation ranges from 16 to 25 inches. Elevation is 4,020 to 6,500 feet. Average annual air temperature is about 62 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These are Chilicotal, Friends, Limpia, Mainstay, Medley, and Mitre soils. Chilicotal soils are calcareous, have ustic aridic moisture regime, light colored surface layers, do not have argillic horizons and occur on lower piedmont slopes. Friends soils have more than 35 percent clay in the control section. Limpia and Medley soils do not have an argillic horizon. Liv soils occur on adjacent slopes, have thicker mollic epipedons, and are moderately deep over igneous bedrock. Mainstay soils are less than 20 inches to igneous bedrock. Mitre soils are shallow to indurated caliche.

DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.

USE AND VEGETATION: Mainly used as rangeland. These soils support a moderate cover of grama grasses with 20 to 50 percent crown cover of oak, juniper, and pine.

DISTRIBUTION AND EXTENT: Volcanic mountains of Southwest Texas. Mainly above 5,000 feet elevation. The series is of minor extent. MLRA 42.

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

SERIES ESTABLISHED: Jeff Davis County, Texas; 1971.

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

Mollic epipedon - the zone from 0 to 17 inches (A and Bt1 horizons)

Argillic horizon - the zone from 10 to 40 inches (Bt1, Bt2 and Bt3 horizons)

Particle size control section -0 the zone from 10 to 30 inches (Bt1. Bt2 and part of the Bt3 horizons)

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 Laboratory data No. 66L165 gives information on the Bt2 horizon.

National Cooperative Soil Survey
U.S.A.