LOCATION LEAKEY TX
Established Series
WJG-LEL-MLG
04/2011
LEAKEY SERIES
The Leakey series consists of well drained, very slowly permeable soils that formed in Pleistocene alluvium. They are moderately deep over a petrocalcic horizon. The soils are on nearly level to gently sloping terraces. Slopes range from 0 to 5 percent.
TAXONOMIC CLASS: Very-fine, smectitic, thermic Petrocalcic Calciusterts
TYPICAL PEDON: Leakey silty clay loam--rangeland. (Colors are for dry soil unless otherwise stated.)
A1--0 to 3 inches; dark grayish brown (10YR 4/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; weak medium and coarse platy structure parting to weak very fine and fine subangular blocky; slightly hard, very friable; many very fine and fine roots and few medium and coarse roots; few very fine tubular pores; about 1 percent by volume subrounded chert cobbles; slightly acid; abrupt smooth boundary.
A2--3 to 8 inches; very dark gray (10YR 3/1) clay, black (10YR 2/1) moist; moderate very fine and fine subangular blocky structure; hard, friable; common very fine and fine roots and few medium and coarse roots throughout; few very fine tubular pores; few medium worm casts; about 5 percent by volume coarse fragments of which 2 percent are subrounded chert pebbles and 3 percent are subrounded chert cobbles; neutral; clear wavy boundary. (combined thickness of A ranges from 4 to 14 inches)
Bss1--8 to 15 inches; brown (7.5YR 4/2), clay, dark brown (7.5YR 3/2) moist; moderate medium angular blocky structure; very hard, firm; common very fine and fine roots and few medium and coarse roots throughout; few very fine tubular pores; about 25 percent by volume very dark gray (10YR 3/1) A material occurs mainly as vertical streaks; few distinct continuous pressure faces on vertical and horizontal faces of peds; few intersecting slickensides; few medium worm casts; about 5 percent by volume coarse fragments of which 2 percent are subrounded chert pebbles and about 3 percent are subrounded chert cobbles; neutral; clear wavy boundary. (0 to 20 inches thick)
Bss2--15 to 21 inches; 65 percent reddish brown (5YR 4/3), and 25 percent dark red (2.5YR 3/6), clay, dark reddish brown (5YR 3/3) and dark red (2.5YR 3/6) moist; moderate medium angular blocky structure; very hard, very firm; common very fine and fine roots and few medium and coarse throughout; few very fine tubular pores; about 10 percent by volume very dark gray (10YR 3/1) clay A material occurs mainly as vertical streaks; few distinct continuous pressure faces on vertical and horizontal faces of peds; few prominent continuous intersecting slickensides that are concentrated in the reddish brown material; about 5 percent by volume coarse fragments of which 2 percent are subrounded chert gravel and 3 percent are subrounded chert cobbles; neutral; abrupt wavy boundary. (4 to 20 inches thick)
Bk--21 to 34 inches; 75 percent reddish brown (5YR 4/4), 15 percent dark red (2.5YR 3/6), and 10 percent reddish brown (5YR 4/3) very stony clay, dark reddish brown (5YR 3/4) dark red (2.5YR 3/6), and dark reddish brown (5YR 3/3) moist; moderate very fine angular blocky structure; hard, firm; common very fine to coarse roots throughout and common very fine and fine roots matted around stones; few very fine tubular pores; few distinct continuous pressure faces on vertical and horizontal faces of peds; about 55 percent by volume coarse subrounded fragments of caliche of which 25 percent are pebbles, 15 percent are cobbles, and 15 percent are stones; slightly alkaline; abrupt wavy boundary. (0 to 20 inches thick)
Bkm1--34 to 36 inches; 40 percent light brownish gray (10YR 6/2), 35 percent reddish yellow (5YR 7/6), and 25 percent pinkish white (5YR 8/2) very cobbly caliche that is strongly cemented by carbonates; massive; the upper 1 to 2 centimeters is light brownish gray, indurated and laminar; the limestone fragments are pinkish white; the strongly cemented caliche is reddish yellow; about 15 percent by volume embedded subrounded limestone pebbles and about 25 percent by volume embedded subrounded limestone cobbles; strongly effervescent; moderately alkaline; clear wavy boundary.
Bkm2--36 to 60 inches; 55 percent pinkish white (5YR 8/2), and 45 percent reddish yellow (5YR 7/6), very cobbly caliche that is moderately cemented by carbonates; massive; the limestone fragments are pinkish white; the caliche is reddish yellow; about 55 percent by volume embedded subrounded limestone fragments of which 25 percent are pebbles and 30 percent cobbles; strongly effervescent; moderately alkaline. (combined thickness of Bkm ranges from 10 to 60 inches)
TYPE LOCATION: Real County, Texas. From the intersection of U.S. Highway 83 and Ranch Road 337 in Leakey, 1.05 miles north on U.S. Highway 83, 4.85 miles north on Ranch Road 336, 0.5 mile west on Cedar Creek Road to bump gate, 300 feet south along fence to top of bluff, 90 feet south and 180 feet west in rangeland. (Latitude: 29 degrees, 47 minutes, and 40 seconds north; Longitude: 99 degrees, 47 minutes, 23 seconds west)
RANGE IN CHARACTERISTICS: Depth to cemented caliche ranges from 20 to 40 inches. Gilgai microrelief is indistinct but slickensides are few to common. When dry the soil has cracks ranging from 0.5 to 2 inches wide that stay open for 90 or more cumulative days in most years. Coarse fragments consist of chert, limestone, and caliche pebbles and cobbles. Surface fragments of chert range from 1 to 10 percent.
The A and Bw/A horizons have hue of 7.5YR or 10YR, value of 2 to 4, and chroma of 1 or 2. Texture is silty clay loam, silty clay, or clay. Clay content ranges from 30 to 55 percent. Coarse fragments range from 1 to 15 percent by volume. Reaction is slightly acid to slightly alkaline.
The Bw and Bss horizons have hue of 2.5YR, 5YR or 7.5YR, value of 2 to 4, and chroma of 1 to 4. Texture is clay with a clay content of 60 to 75 percent. Coarse fragments range from 1 to 15 percent by volume. Reaction is slightly acid to slightly alkaline.
The Bk horizon, where present, has hue of 2.5YR, 5YR, or 7.5YR, value of 2 to 4, and chroma of 1 to 4. Texture is very stony clay, gravelly clay, very gravelly clay, or cobbly clay with clay content of 60 to 75 percent. Coarse fragments range from 1 to 60 percent by volume. Most fragments appear to be remnants of a degraded petrocalcic horizon. Reaction is slightly to moderately alkaline.
The Bkm horizon is indurated or strongly cemented in the upper part and weakly to strongly cemented in the lower part. Limestone and chert pebbles, cobbles, and stones make up 20 to 70 percent of the volume.
COMPETING SERIES: There are no other competing series in the same family. Similar soils include the
Anhalt,
Campwood,
Crawford,
Depalt,
San Saba,
Tobosa and
Topia series. These soils do not have a petrocalcic horizon within 40 inches, do not have more than 60 percent clay in the control section. Crawford and San Saba soils have hard limestone bedrock within 40 inches. Topia soils do not have slickensides. Anhalt soils lack a petrocalcic horizon and have soft limestone bedrock substrata.
GEOGRAPHIC SETTING: Leakey soils are on high terraces in deeply incised valleys. They formed in highly weathered Pleistocene age alluvium derived from areas of cherty Segovia Limestone (Lower Cretaceous) and Glenrose Limestone. Slope gradients are mainly less than 3 percent but range from 0 to 5 percent. The climate is subhumid. Mean annual precipitation ranges from 26 to 32 inches and mean annual temperature ranges from 65 to 69 degrees F. Frost-free days range from 220 to 240 and elevation ranges from 1,000 to 2,000 feet. Thornthwaite annual P-E index ranges from about 36 to 44.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing
Campwood and
Crawford series, and the
Dev,
Eckrant,
Kerrville,
Knippa,
Mailtrail,
Mereta,
Oakalla,
Oplin, and
Real series. Eckrant, Kerrville, Oplin, and Real soils occur on erosional uplands higher in the landscape. These soils are underlain by hard limestone bedrock within 20 inches. Mailtrail and Mereta soils are on similar landscapes, and have a petrocalcic horizon within 20 inches. Dev and Oakalla series are loamy soils on lower floodplain landscapes.
DRAINAGE AND PERMEABILITY: The soil is well drained. Runoff is low on slopes less than 1 percent, medium on 1 to 3 percent slopes and high on 3 to 5 percent slopes. Permeability is very slow.
USE AND VEGETATION: Used for rangeland and pasture. Native grasses include curly mesquite, Texas wintergrass, little bluestem, and Indiangrass. Woody plants include live oak, ashe juniper, post oak, agarito, and persimmon. Some areas are seeded to KR bluestem.
DISTRIBUTION AND EXTENT: Eastern Edwards Plateau of Central Texas. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Real County, Texas; 2000. The name is from the town of Leakey, county seat of Real County.
REMARKS: The Leakey series was formerly included in the Topia and Anhalt series. The name is pronounced Lay-kee.
Diagnostic features recognized in this pedon are:
Mollic epipedon--0 to 21 inches (A1, A2 and Bss horizons).
Slickensides--8 to 21 inches (Bss horizon).
Calcic - 21 to 34 inches (Bk horizon)
Petrocalcic - 34 to 60 inches (Bkm1 and Bkm2 horizons).
Deep, wide cracks that open 90 or more cumulative days in most years.
ADDITIONAL DATA: Texas Agricultural Experiment Station, Soil Characterization Lab data is available for the type location (S90TX-385-001).
National Cooperative Soil Survey
U.S.A.