LOCATION GRAVA TXEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, hyperthermic Petrocalcic Paleustolls
TYPICAL PEDON: Grava very gravelly sandy clay loam, 4 percent slope in rangeland; elevation is 198 m (649 ft). (Colors are for dry soil unless otherwise stated.)
A--0 to 13 cm (0 to 5 in); reddish brown (5YR 4/3) very gravelly sandy clay loam, dark reddish brown (5YR 3/3) moist; weak fine subangular blocky structure parting to weak fine and medium granular; hard, firm slightly sticky and slightly plastic; few medium and coarse roots; 40 percent rounded siliceous pebbles 12 to 51 mm (1/2 to 2 in) in diameter; common interstitial pores; neutral; clear smooth boundary. (thickness of the A horizon is 10 to 20 cm [4 to 8 in])
Bt1--13 to 46 cm (5 to 18 in); dark reddish brown (2.5YR 3/4) extremely gravelly clay, dark reddish brown (2.5YR 3/3) moist; moderate coarse prismatic structure parting to moderate medium and coarse angular blocky; very hard, very firm; sticky and plastic; few medium and coarse roots; common distinct clay films on surfaces of peds and pebbles; 75 percent rounded siliceous pebbles 12 to 51 mm (1/2 to 2 in) in diameter; neutral; clear wavy boundary.
Bt2--46 to 69 cm (18 to 27 in); reddish brown (2.5YR 4/4) extremely gravelly clay, dark reddish brown (2.5YR 3/4) moist; moderate coarse prismatic structure parting to moderate medium and coarse angular blocky; very hard, very firm, very sticky and very plastic; few medium roots; common distinct clay films on surfaces of peds and pebbles; 75 percent siliceous pebbles 12 to 51 mm (1/2 to 2 in) in diameter; neutral; abrupt wavy boundary. (combined thickness of Bt horizons is 38 to 102 cm [15 to 40 in])
Bk--69 to 76 cm (27 to 30 in); reddish yellow (5YR 6/6) very gravelly clay loam, yellowish red (5YR 5/6) moist; weak medium and coarse subangular blocky structure parting to weak fine and medium angular and subangular blocky; very hard, very firm, slightly sticky and slightly plastic; few very fine and coarse roots; 40 percent siliceous pebbles and angular fragments of indurated calcrete 12 to 51 mm (1/2 to 2 in) in diameter; violently effervescent; moderately alkaline; abrupt smooth boundary. (thickness of the Bk horizon is 0 to 20 cm [0 to 8 in])
Bkkm1--76 to 99 cm (30 to 39 in); pinkish white (5YR 8/2) strongly cemented calcium carbonate, pink (5YR 8/3) moist; 40 percent siliceous pebbles cemented in the matrix; violently effervescent; moderately alkaline; abrupt smooth boundary. (combined thickness of the Bkkm horizon is 104 to 150 cm [41 to 59 in])
Bkkm2--99 to 203 cm (39 to 80 in); pink (5YR 8/3) weakly cemented calcium carbonate, pink (5YR 8/4) moist; approximately 40 percent siliceous pebbles imbedded in the matrix; approximately 8 percent concretions of calcium carbonate less than 3 mm in diameter; violently effervescent; moderately alkaline.
TYPE LOCATION: Duval County, Texas; from the intersection of Texas Highway 359 and Farm Road 2295 in Benavides; 15.5 miles west on Farm Road 2295, 3.0 miles north on Texas Highway 16; east 2.7 miles on private ranch road; 100 feet west in rangeland. USGS Parilla Creek NW, Texas topographic quadrangle; Latitude: 27 degrees, 37 minutes, 44 seconds N; Longitude: 98 degrees, 38 minutes, 14 seconds W. NAD 83.
RANGE IN CHARACTERISTICS:
Soil Moisture: The soil moisture control section (SMCS) remains moist in some or all parts for less than 90 consecutive days per year during the months of July through August and March through May. The SMCS is driest during the months June through September and December through February. Aridic/ustic moisture regime.
Mean annual soil temperature: 21 to 24 degrees C (72 to 75 degrees F)
Depth to argillic horizon: 10 to 20 cm (4 to 8 in)
Depth to petrocalcic horizon: 51 to 102 cm (20 to 40 in)
Clay content of the particle-size control section: 40 to 60 percent
Coarse Fragments: 35 to 80 percent, and increase with increasing depth
A Horizon
Hue: 5YR or 7.5YR
Value: 3 to 5
Chroma: 2 or 3
Texture: sandy clay loam (very gravelly counterpart)
Clay content: 20 to 30 percent
Coarse fragments: 15 to 60 percent siliceous gravel
Base saturation: 75 to 90 percent
Calcium carbonate equivalent: 0 to 2 percent
EC (dS/m): 0 to 1
Gypsum: 0 to 1 percent
SAR: 0 to 1
Reaction: neutral or slightly alkaline
Bt Horizon
Hue: 2.5YR to 7.5YR
Value: 3 to 6
Chroma: 3 to 6
Texture: clay (gravelly, very gravelly, or extremely gravelly counterparts)
Clay content: 40 to 65 percent
Coarse fragments: 35 to 80 percent siliceous gravel
Base saturation: 85 to 95 percent
Calcium carbonate equivalent: 0 to 2 percent
EC (dS/m): 0 to 2
Gypsum: 0 to 1 percent
SAR: 0 to 1
Reaction: slightly acid or neutral
Bk Horizon (where present)
Hue: 2.5YR to 7.5YR
Value: 3 to 6
Chroma: 4 to 6
Texture: clay loam or clay (gravelly, very gravelly, or extremely gravelly counterparts)
Clay content: 27 to 45 percent
Coarse fragments: 35 to 80 percent siliceous gravel
Base saturation: 90 to 100 percent
Calcium carbonate equivalent: 30 to 55 percent
EC (dS/m): 0 to 2
Gypsum: 0 to 1 percent
SAR: 0 to 1
Reaction: slightly alkaline or moderately alkaline
Bkkm Horizon - strongly cemented with a laminar cap from 3 to 5 cm (1 to 2 in) thick over moderately cemented gravelly or very gravelly secondary calcium carbonate that becomes less cemented with depth.
Hue: 10YR
Value: 5 to 8
Chroma: 2 to 6
Coarse fragments: 35 to 60 percent gravel and 5 to 10 percent stones imbedded in matrix
Base saturation: 100 percent
Calcium carbonate equivalent: 40 to 80 percent
EC (dS/m): 0 to 1
Gypsum: 0 to 1 percent
SAR: 0 to 1
Reaction: moderately alkaline
COMPETING SERIES: There are no competing series. Similar soils are the
Hindes (TX),
Jimenez (TX),
Quemado (TX),
Quihi (TX),
Mitre (TX), and
Yologo (TX) series.
Hindes series: do not have a petrocalcic horizon, and have mixed mineralogy.
Jimenez series: do not have an argillic horizon, have a petrocalcic horizon within 51 cm (20 in) of the surface, and average less than 35 percent clay in the fine earth fraction.
Quemado and Yologo series: have a petrocalcic horizon within 51 cm (20 in) of the surface.
Quihi series: have mixed mineralogy and have a typic/ustic moisture regime.
Mitre series: have mean annual soil temperature less than 20 degrees C (70 degrees F), and have a petrocalcic horizon within 51 cm (20 in) of the surface.
GEOGRAPHIC SETTING:
Parent material: residuum derived from gravelly alluvium
Landform: interfluves
Slope: 0 to 8 percent
Mean annual temperature: 20 to 22 degrees C (70 to 73 degrees F)
Mean annual precipitation: 559 to 660 mm (22 to 26 in)
Frost-free period: 270 to 320 days
Elevation: 122 to 244 m (400 to 800 ft)
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Benavides,
Cuevitas,
Delmita,
Olmedo,
Piedras, and
Randado series.
Benavides soils: side-slopes of interfluves and do not have a petrocalcic horizon.
Cuevitas, Delmita, Olmedo, Randado soils: similar positions and have less than 15 percent gravel in the particle-size control section.
Piedras soils: similar positions, and have less than 35 percent clay in their particle-size control section.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately slow. Runoff is high.
USE AND VEGETATION: Used mainly for livestock grazing and wildlife habitat. Native woody vegetation includes black brush, mountain laurel, mesquite, hog plum, cenezo, guayacan, prickly pear, coyotillo, amagosa and catclaw. Grass species include sideoats grama, buffalograss, perennial threeawn, Arizona cottontop, plains bristlegrass, and hooded windmillgrass. The ecological site is Gravelly Ridge, PE 19-44 (R083CY454TX).
DISTRIBUTION AND EXTENT: Central Rio Grande Plain of Texas; LRR I; MLRA 83C; minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Duval County, Texas, 1998. The name Grava is Spanish for Gravel.
REMARKS: The Grava series was formerly mapped in the Quemado and Yologo series.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 46 cm (0 to 18 in). (A and Bt1 horizons)
Argillic horizon: 13 to 69 cm (5 to 27 in). (Bt horizons)
Petrocalcic horizon: 76 to 203 cm (30 to 80 in). (Bkkm horizons)
ADDITIONAL DATA:
The assignment of the cation-exchange activity class is supported by laboratory data number S97TX-131-001 from the type location in Duval County, Texas. Particle-size analysis was performed at the local project office for 3 pedons from Duval County.
TAXONOMIC VERSION: Keys to Soil Taxonomy, Tenth edition, 2006