LOCATION MADRONE                 TX

Established Series
Rev. ACT
12/2010

MADRONE SERIES

The Madrone series consists of moderately deep, well drained, moderately slowly permeable soils that formed in clayey gravelly materials over igneous bedrock. These strongly sloping to steep soils occur on igneous mountains. Slopes range from 8 to 45 percent.

TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Typic Paleustalfs

TYPICAL PEDON: Madrone very cobbly silt loam. (Colors are for dry soil unless otherwise stated.)

Oi--0 to 1 inch; partially decomposed organic materials; abrupt smooth boundary. (0 to 4 inches thick)

A--1 to 6 inches; dark grayish brown (10YR 4/2) very cobbly silt loam, very dark brown (10YR 2/2) moist; strong fine granular structure; soft, very friable; many roots; 45 percent igneous rock fragments comprising 20 percent gravel, 20 percent cobbles, and 5 percent stones; neutral; clear smooth boundary. (3 to 6 inches thick)

E--6 to 10 inches; pale brown (10YR 6/3) very cobbly loam, brown (10YR 4/3) moist; moderate fine granular structure; soft, very friable; many roots; 45 percent igneous rock fragments comprising 20 percent gravel, 20 percent cobbles, and 5 percent stones; strongly acid; abrupt smooth boundary. (2 to 12 inches thick)

Bt1--10 to 23 inches; brown (7.5YR 5/2) very cobbly clay, brown (7.5YR 4/2) moist; strong medium blocky structure; hard, firm, plastic, sticky; few roots; few distinct clay films; vertical cracks with lenses of material from horizon above; 50 percent igneous rock fragments comprising 20 percent gravel, 20 percent cobbles, and 10 percent stones; very strongly acid; clear smooth boundary. (6 to 20 inches thick)

Bt2--23 to 37 inches; brown (7.5YR 5/2) very cobbly clay, brown (7.5YR 4/2) moist; moderate medium angular blocky structure; very hard, very firm, plastic, sticky; a few reddish brown (5YR 5/3) mottles; 50 percent igneous rock fragments comprising 20 percent gravel, 20 percent cobbles, and 10 percent stones; very strongly acid; abrupt irregular boundary. (0 to 18 inches thick)

R--37 to 41 inches; fractured igneous bedrock; seams in rock filled with brown (7.5YR 5/2) clay.

TYPE LOCATION: Jeff Davis County, Texas; about 11.5 miles west of McDonald Observatory on Texas Highway 118, then 3.0 miles south on ranch road up Loghouse Canyon. (Latitude: 30 degrees, 41 minutes, 05 seconds North: Longitude: 104 degrees, 09 minutes, 38 seconds West.)

RANGE IN CHARACTERISTICS:
Depth to bedrock and solum thickness; 21 to 40 inches.

Rock fragments: 35 to 80 percent igneous rock fragments comprising 15 to 50 percent gravel, 5 to 40 percent cobbles, and 0 to 30 percent stones.

Soil moisture: The soil is dry in some part of the control section for more than 120 but less than 180 cumulative days during the growing season. Typic ustic moisture regime.

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

E horizon
Hue: 7.5YR or 10YR
Value: 6 or 7 dry, 4 moist
Chroma: 2 or 3, dry or moist
Texture: sandy loam, loam, or clay loam
Reaction: neutral to slightly acid.

Bt horizons
Hue: 5YR to 10YR
Value: 4 or 5, dry or moist
Chroma: 2 to 4, dry or moist
Texture: clay, silty clay
Clay content: 45 to 60 percent
Reaction: medium acid to very strongly acid.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Madrone soils are on hills and mountains. Bedrock is of extrusive igneous rocks such as rhyolite, trachyte, or related igneous rocks. The regolith is a moderately deep stony mantle over igneous bedrock. Slopes are mostly 8 to 45 percent. They are on the higher elevations of mountains usually between 5,575 and 7,800 feet. Mean annual precipitation ranges from 18 to 26 inches. Mean annual temperature ranges from 52 to 59 degrees F. Frost free days range from 160 to 200 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are Liv, Loghouse, Mainstay series, and Puerta of the competing series. Liv and Mainstay soils occur below 6,200 feet elevation. Loghouse soils have a loamy-skeletal control section.

DRAINAGE AND PERMEABILITY: Madrone soils are well drained, Runoff is medium to high and Permeability is moderately slow.

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

DISTRIBUTION AND EXTENT: At the higher elevations of the Davis Mountains in far west Texas. The series is of moderate extent. MLRA 42.

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

SERIES ESTABLISHED: Jeff Davis County, Texas; 1971.

REMARKS: The classification was changed in 1992 from Udic Paleustalfs to Typic Paleustalfs.

Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - the zone from 1 to 10 inches (A and E horizons)

Argillic horizon - the zone from 10 to 37 inches (Bt horizons)

Lithic contact - the boundary at 37 inches

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: Lab Data on the A2 horizon, LSL No. 66L167.

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National Cooperative Soil Survey
U.S.A.