LOCATION HORNBECK LATentative Series
TAXONOMIC CLASS: Fine, smectitic, thermic Aquic Hapluderts
TYPICAL PEDON: Hornbeck clay, in old abandon field (colors are for moist soil unless otherwise stated.)
A1--0 to 7 inches; very dark gray (10YR 3/1) clay; weak medium subangular blocky structure; firm, many fine and very fine roots; few fine calcium carbonate masses; moderately alkaline; gradual wavy boundary. (3 to 8 inches thick)
A2--7 to 22 inches; black (10YR 2/1) clay; weak medium subangular blocky structure; very firm; many fine and very fine roots; common very fine calcium carbonate concretions; moderately alkaline; abrupt wavy boundary. (7 to 21 inches thick)
Bkss1--22 to 35 inches; yellowish brown (10YR 5/4) clay; many medium faint light brownish gray (10YR 6/2),, few medium faint dark gray (10YR 4/1) and common fine faint yellowish brown mottles; moderate medium angular blocky structure; very firm; many very fine roots; common small and medium slickensides; many medium and large pockets of calcium carbonate concretions (CaCo3 equivalent 23-27); moderately alkaline; gradual wavy boundary. (4 to 21 inches thick)
Bkss2--35 to 50 inches; light brownish gray (2.5Y 6/2) clay; many fine faint olive yellow (2.5Y 6/6) mottles; moderate coarse angular blocky structure, parting to weak medium prismatic structure; very firm; common very fine roots; many large intersecting slickensides; many large pockets of calcium carbonate concretions (CaCo3 equivalent 17-21), alkaline; diffuse wavy boundary. (8 to 20 inches thick)
Bkss3--50 to 67 inches; mottled, light brownish gray (2.5Y 6/2) yellowish brown (10YR 5/6) and brown (7.5YR 5/6) clay; moderate medium angular blocky structure; very firm; few very fine roots; large crawfish hole; many large and common very large slickensides that intersect; common black stains; many medium and large pockets of calcium carbonate concretions; (CaCo3 equivalent 17-21) moderately alkaline; clear wavy boundary. (0 to 20 inches thick)
C1--67 to 75 inches; light brownish gray (10YR 6/2) silty clay loam; common medium distinct light yellowish brown (2.5Y 6/4) and olive yellow (2.5Y 6/8) mottles; weak medium subangular blocky structure; evident of bedding plains present; firm; large gray (N5/) crawfish hole; alkaline; abrupt wavy boundary. (4 to 12 inches thick)
C2--75 to 86 inches; yellowish brown (10YR 5/8) clay; common fine distinct red (2.5YR 5/6), and many coarse light brownish gray (2.5Y 6/2) mottles; moderate medium angular blocky structure; friable; many, very thin clay films; alkaline. (0 to 20 inches thick)
TYPE LOCATION: Vernon Parish, Louisiana; 2 miles south of New Llano on Hwy. 171, 0.2 mile west on Parish road (beside the old drive-in theater); 200 feet south in abandon field; SE1/4, NE1/4 SEC.10 T.1N, R.9W, USGS New Llano topographic quadrangle. (Longitude: 93 degrees 16 minutes 32 seconds west; Latitude: 31 degrees 5 minutes 1 second north)
RANGE IN CHARACTERISTICS: Depth to the Bkss horizon ranges from 18 to 25 inches. Depth to secondary calcium carbonate accumulation range from 25 to 35 inches. Depth to slickensides range from 7 to 22 inches. Untilled soils have a gilgai microrelief.
The A1 or Ap horizon has hue of 10YR, value of 5 or 6, and chroma of 4 in the upper part. The lower part of the Bkss horizon has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 2 or 4, or is mottled in shades of gray, brown, olive, or yellow. Texture is clay or silty clay. Reaction ranges from neutral to moderately alkaline. In some pedons fossils of oysters and other shellfish are common in the Bkss horizon.
The C horizon where present has colors in shades of gray, olive, or yellow. The texture ranges from silty clay loam to clay. It is moderately alkaline to alkaline.
COMPETING SERIES: These are the Beaumont, Brooksville, Burleson, Clarita, Eutaw, Garner, Hollywood, Houston, Houston Black, Keiffer, Lake Charles, Okolona, Randall, Roscoe, and San Saba series. Beaumont, Eutaw, and Garner soils have color value of 3.5 or more within a depth of 12 inches in more than half of each pedon. Brooksville, Houston, Keiffer and Okolona soils have color chroma of 1.5 or greater in the A horizon. In addition, Houston soils have more than 60 percent clay in the control section. Hollywood soils have limestone bedrock. Burleston, Clarita, Houston Black, Randall, Roscoe, and San Saba soils have cracks that remain open more than 90 cumulative days in most years. Lake Charles soils have matrix color of less than 1.5 to a depth of 40 inches or more and lack Bkss horizons with soft powdery lime.
GEOGRAPHIC SETTING: Hornbeck soils are on uplands which have depressional or sloping relief. Slopes range from 0 to 8 percent. These soils formed in clayey, calcareous sediments of Tertiary age. Slopes range from 1 to 8 percent. Mean annual precipitation ranges from 45 to 60 inches. The mean annual temperature is 66 degrees F, and frost free days range from 275 to 300.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Bayoudan, Bellwood, Eastwood, Falkner, Keiffer, Oktibbeha, and Vaiden soils. Bayoudan, Bellwood & Eastwood soils are acid throughout. Falkner soils have a fine silty control section. Keiffer soils are carbonatic. The Oktibbeha and Vaiden soils have acid upper sola underlain by carbonates.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow to medium runoff; very slow permeability.
USE AND VEGETATION: Almost all areas of Hornbeck soils are in loblolly and shortleaf pine forests. The remaining areas are open prairies and native pasture. Eastern red cedar, native grasses, forbs, and shrubs grow in the prairies.
DISTRIBUTION AND EXTENT: Coastal Plain Uplands of Louisiana and possibly Alabama, Mississippi, and eastern Texas. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES PROPOSED: Vernon Parish, Louisiana, 1993. Name is derived from a small community in Vernon Parish.
REMARKS: This soil was formerly included with the Hollywood series.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: from a depth of 0 to 22 inches (includes the A1 and A2 horizons).
Cambic horizon: from a depth of 22 to 75 inches (includes the Bkss1, Bkss2, Bkss3, and C. horizons).
Redoximorphic features - 22 to 86 inches.
Intersecting slickensides beginning at about 22 inches to a depth of 67 inches (Bkss1, Bkss2, Bkss3 horizons).
ADDITIONAL DATA: Laboratory data on the typifying pedon was obtained from National Soil Survey Laboratory, sample 589LA115025. Other data includes; NSSL data 589LA115025A. LSU data 586LA115105-14, 586LA115219-1.