LOCATION AVANT AREstablished Series
TAXONOMIC CLASS: Loamy-skeletal, siliceous, semiactive, thermic Typic Hapludults
TYPICAL PEDON: Avant very gravelly silt loam, on a 40 percent slope, in forest. (Colors are for moist soil unless otherwise stated.)
A--0 to 8 cm (0 to 3 in); brown (10YR 4/3) very gravelly silt loam; weak medium granular structure; very friable; common fine and very fine roots; about 45 percent by volume angular chert fragments less than 8 cm (3 in) in diameter; very strongly acid; clear smooth boundary. (5 to 13 cm (2 to 5 in thick))
E--8 to 18 cm (3 to 7 in); yellowish brown (10YR 5/4) very gravelly silt loam; weak medium subangular blocky structure; very friable; common fine and very fine roots; about 40 percent by volume angular chert fragments less than 8 cm (3 in) in diameter; very strongly acid; clear smooth boundary. (8 to 25 cm (3 to 10 in thick))
BE--18 to 43 cm (7 to 17 in); yellowish brown (10YR 5/6) very gravelly silt loam; weak medium subangular blocky structure; very friable; common fine roots; about 35 percent by volume angular chert fragments less than 8 cm (3 in) in diameter and about 15 percent by volume 8 to 25 cm (3 to 10 in) in diameter; very strongly acid; gradual wavy boundary. (0 to 25 cm (0 to 10 in thick))
Bt--43 to 91 cm (17 to 36 in); strong brown (7.5YR 5/6) extremely cobbly silty clay loam; moderate medium subangular blocky structure; firm; few fine roots; few faint clay films on faces of peds; about 25 percent by volume angular chert fragments less than 3 inches in diameter and about 35 percent by volume angular chert fragments 8 to 25 cm (3 to 10 in) in diameter; very strongly acid; abrupt irregular boundary. (38 to 89 cm (15 to 35 in thick))
R/C--91 to 107 cm (36 to 42 in); alternating strata of highly fractured, hard, chert bedrock and fine earth material with a dip of 45 degrees from the horizontal. R material consists of highly fractured, hard, chert bedrock with thin clay coatings in cracks; horizontal spacing between cracks is typically 10 cm or more; strata of R material range from 30 to 91 cm (1 to 3 ft) or more in thickness. The fine earth or C material consists of mottled yellowish brown (10YR 5/6), yellowish red (5YR 5/6), and gray (10YR 6/1) stratified clay, clay loam and very fine sandy loam; strata of C material range from less than 3 to 15 cm (1 in to 6 in) in thickness; C material is very strongly acid.
TYPE LOCATION: Garland County, Arkansas; approximately 2,500 feet south of the northwest corner of section 3 in the SW1/4SW1/4NW1/4, sec. 3, T. 2 S.,
R. 18 W.
RANGE IN CHARACTERISTICS: Solum thickness and depth to fractured, rippable, chert bedrock ranges from 51 to 102 cm (20 to 40 in) and due to the irregular boundary between the Bt horizon and the underlying tilted bedrock, it is extremely variable within short distances. Reaction ranges from medium acid to very strongly acid throughout. Content of chert fragments ranges from 35 to 90 percent by volume throughout.
A horizon:
Hue: 10YR
Value : 3 or 4
Chroma: 2 or 3
or Hue: 7.5YR
Value: 4
Croma of 2, 3 or 4
Where the A horizon has moist value of 3 and chroma of 2 or 3, it is less than 6 inches thick.
Texture: very gravelly loam, very gravelly silt loam, or their extremely gravelly, very cobbly, or extremely cobbly analogs
E horizon has hue of 10YR
Value: 5 or 6
Chroma: of 3 or 4
Texture: very gravelly loam, very gravelly silt loam, or their extremely gravelly, very cobbly, or extremely cobbly analogs
BE horizon:
Hue: 10YR or 7.5YR
Value: 5
Chroma: 4, 6 or 8
Texture: very gravelly loam, very gravelly silt loam, or their extremely gravelly, very cobbly, or extremely cobbly analogs.
Bt horizon:
Hue: 10YR, 7.5YR or 5YR
Value: 5 or 6
Chroma: 4, 6, or 8
or Hue: 5YR:
Value: 4
Chroma: 4, 6, or 8
Texture: very gravelly loam, very gravelly silt loam, very gravelly silty clay loam, or very gravelly clay loam, or their extremely gravelly, very cobbly, or extremely cobbly analogs
The R/C horizon
Consists of alternating strata of highly fractured, hard, chert bedrock and fine earth material with a dip ranging from 30 degrees to near vertical. The
R material is typically, highly fractured, hard, chert bedrock. Horizontal spacing between fractures is typically 10 cm or more. Due to the fractured nature of the chert
bedrock, excavation can normally be made with common construction equipment. The C material has stratified textures ranging from clay to very fine sandy loam
with colors in shades of brown, gray, red or yellow. Because of faulting and folding, this horizon is extremely variable within short distances.
COMPETING SERIES: These are Bigfork, Cobstone, Lillington, Saffell, Steprock, Subligna, and Zafra series in the same family.
Bigfork soils are moderately deep over massive chert or novaculite.
Cobstone, Lillington, Saffell and Subligna soils are deeper than 40 inches to bedrock.
Steprock soils are moderately deep over level bedded, weathered, interbedded sandstone, siltstone and shale.
Zafra soils are underlain with hard sandstone which is tilted 20 to 60 degrees from horizontal.
GEOGRAPHIC SETTING: Avant soils are on sides and tops of hills, mountains, and ridges of the Ouachita Mountains. Slopes range from 3 to 60 percent.
These soils formed in residuum from tilted, extremely fractured chert bedrock. The mean annual temperature ranges from 59 to 63 degrees F., and the annual
precipitation ranges from 50 to 56 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing
Bigfork series and the
Bengal,
Bismarck,
Carnasaw and
Yanush series.
Bigfork soil are on upper side slopes and tops of mountains and ridges.
Bengal, Bismarck and Carnasaw soils occur on adjacent mountains and formed in residuum from shale or interbedded sandstone and shale bedrock.
Yanush soils occur on lower sideslopes and footslopes, are more than 60 inches to bedrock.
DRAINAGE AND PERMEABILITY: Avant soils are well drained. Runoff is medium on the gently sloping areas and rapid to very rapid on the steeper slopes. Permeability is moderate. Hydraulic conductivity is moderate.
USE AND VEGETATION: Used mainly as woodland. The main trees are shortleaf pine, loblolly pine, blackjack oak, post oak, southern red oak, white oak, and hickory.
DISTRIBUTION AND EXTENT: Ouachita Mountains of Arkansas and possibly Oklahoma; MLRA 119. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Garland County, Arkansas; 1986. The series name is the name of a nearby community.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon-soil surface to 43 cm (0 to 17 in)
Argillic horizon-zone from 43 to 91 cm (17 to 36 in)
These soils were formerly included in the Bigfork series.
ADDITIONAL DATA: National Soil Survey Lab data for 3 pedons. Sample Numbers S84AR-051-004, S84AR-051-001, and S83AR-051-001.
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