LOCATION GIBBONSCREEK TXEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, semiactive, nonacid, thermic Typic Ustorthents
TYPICAL PEDON: Gibbonscreek clay loam--pasture. (Colors are
for dry soil unless otherwise stated.)
Ap--0 to 8 inches; light gray (2.5Y 7/2) clay loam,
light brownish gray (2.5Y 6/2) moist; common medium distinct
olive (5Y 5/3) and pale brown (10YR 6/3) mottles; weak fine
granular and weak fine platy structure; hard, firm, sticky
and plastic; many fine roots; few fine fragments of lignite
or carbonaceous shale; common fine to medium fragments of
weakly cemented siltstone and glauconite; ECe 3.0 mmhos/cm;
slightly acid; clear wavy boundary. (2 to 15 inches thick)
C1--8 to 17 inches; light gray (2.5Y 7/2) clay loam,
light brownish gray (2.5Y 6/2) moist; common medium distinct
brown (10YR 5/3) and olive (5Y 5/3) mottles; massive; hard,
firm, sticky and plastic; few fine roots; few fine fragments
of lignite coal; common fine and medium fragments of weakly
cemented siltstone and glauconite; ECe 2.6 mmhos/cm; medium
acid, clear wavy boundary. (6 to 25 inches thick)
C2--17 to 80 inches; light gray (2.5Y 7/2) clay loam,
light brownish gray (2.5Y 6/2) moist; massive; hard, firm,
sticky and plastic; few fine roots; few fine and medium
fragments of lignite coal; common medium and large fragments
of weakly cemented siltstone and olive (5Y 5/3) glauconite;
ECe 2.3 mmhos/cm; neutral.
TYPE LOCATION: Grimes County, Texas; from Farm Road 244 in
Carlos; 2.6 miles west on Texas Highway 30; 2.1 miles south
on county road; 1500 feet east of road in pasture.
RANGE IN CHARACTERISTICS: The rooting depth is greater than
80 inches. Mining operations have mixed the materials from
about 30 to 150 feet deep. The soils are mainly slightly
acid or neutral but range from strongly acid to moderately
alkaline and these ranges are within some pedons. Rock
fragments and pebbles range from 0 to 5 percent. Lignite
and carbonaceous shale fragments commonly less than 3 inches
across range from a trace to about 5 percent.
The A horizon has hue of 10YR to 5GY, value of 4 to 8, and
chroma of 1 to 4. It is clay loam, silty clay loam, sandy
clay loam, silty clay, or clay. Fragments or masses of
shale and lignite range from few to many in darker and
lighter colors. Some pedons contain a few small fragments
of iron pyrite.
The C horizon has hue of 10YR to 5GY, value of 4 to 8, and
chroma of 1 to 4. Masses or mottles with these colors as
well as red, yellow, brown and gray colors range from none
to few. It is sandy clay loam, clay loam, or silty clay
loam. Some pedons contain layers, streaks, or bodies of
silty clay, clay, fine sandy loam or loamy sand. The
weighted average clay content of the 10- to 40-inch control
section ranges from 20 to 35 percent. Fragments of
siltstone or sandstone range from none to 15 percent.
Content of fragments decreases the first few years following
mining, due to weathering. Exchangeable sodium ranges from
5 to 12 percent and the electrical conductivity ranges from
1 to 4 mmhos/cm.
COMPETING SERIES: There are no competing series in the same
family. Similar series include
Barge,
Bigbrown,
Brilliant,
Drake,
Grayrock,
Kanima, and
Palmerdale series. Barge and
Kanima soils have fragments of diagnostic horizons within
the control section. Bigbrown soils have fine-silty control
sections and exchangeable sodium percentage less than 5
percent. Brilliant and Palmerdale soils have loamy-skeletal
control sections. Grayrock soils have fine-silty control
sections and are moist for longer periods in the moisture
control section. Drake soils are calcareous throughout, are
dry for longer periods of time and are not on mine spoil
materials.
GEOGRAPHIC SETTING: Gibbonscreek soils are on gently
sloping to strongly sloping surfaces. They are on mine
spoil areas where draglines used in coal strip mining
operations have mixed overburden materials. Slope gradients
range from 1 to 20 percent with plane or convex surfaces.
The soils are being reclaimed immediately after mining
operations and therefore slopes are gentle and fairly
uniform over large tracts. The mean annual temperature
ranges from 65 to 70 degrees F. Average annual
precipitation ranges from 32 to 44 inches, and Thornthwaite
P-E indices range from 54 to 68. The lignite seams are
mainly in the Jackson Group of late Eocene Epoch. However,
in some areas, Quaternary age materials are part of the
overburden and are also intermixed. Mining operations, to
some degree, are mixing soil materials from the surface to a
depth of about 30 to 150 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Arol,
Axtell,
Burlewash,
Elmina,
Falba,
Lufkin,
Shiro and Tabor
series. All of these soils have Bt horizons and are on
nearby unmined areas.
DRAINAGE AND PERMEABILITY: Well drained, medium runoff.
The soil has moderate permeability for a few years after
reclamation, but the permeability decreases with time and consolidation.
USE AND VEGETATION: Most areas are in pasture. Some areas
are idle and in various stages of reclamation and plant
succession. About 1/2 of smoothed areas are being
established to pastures of coastal bermudagrass. Other
areas are being established to native grasses. Vegetation
before mining was mid and tall grasses with post oak and
blackjack oak trees.
DISTRIBUTION AND EXTENT: South central Texas. The series
is of minor extent, but is increasing as mining operations
continue. The series is expected to be moderately
extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Grimes County, Texas; 1988. The name
is from a creek near the mining area.
REMARKS: Gibbonscreek soils were previously mapped as mine
spoil. The type location was mined in 1982, and was
smoothed and reclaimed in 1983.
Diagnostic horizons and features recognized in this pedon
are:
Ochric epipedon, 0 to 8 inches.
Parent materials consist of lignite mining overburden.
ADDITIONAL DATA: Soil test analysis provided by Texas
Municipal Power Agency on 12 pedons, and field lab data by
Soil Survey Party.