LOCATION OAKHILL VAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, active, mesic Typic Hapludalfs
TYPICAL PEDON: Oakhill gravelly silt loam, 2 to 7 percent slopes, in a cultivated area. (Colors are for moist soil)
Ap--0 to 8 inches; brown (10YR 4/3) gravelly silt loam; moderate fine and medium granular structure; very friable; many fine, medium and coarse roots; 25 percent angular basalt gravel; strongly acid; clear smooth boundary. (0 to 10 inches thick)
Bt--8 to 25 inches; strong brown (7.5YR 5/8) very gravelly loam; weak fine subangular blocky structure; friable; slightly plastic, sticky; many fine and medium roots; common thin clay films on faces of peds; 45 percent angular basalt gravel; 2 percent cobbles; moderately acid; gradual smooth boundary. (10 to 35 inches thick)
C--25 to 34 inches; variegated with yellowish brown (10YR 5/6), dark yellowish brown (10YR 3/4), pale yellow (5Y 8/2) and olive (5Y 5/3) very gravelly sandy loam; massive; friable; common fine and medium roots; common Fe-Mn coatings and fine concretions; 55 percent basalt gravel; slightly acid; clear smooth boundary. (0 to 20 inches thick)
R--34 inches; olive yellow (5Y 6/8) basalt bedrock; difficult to dig with backhoe at 45 inches.
TYPE LOCATION: Prince William County, Virginia; about 3/4 mile south of route VA 234 and about 1600 feet east of Route U. S. 15.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 18 to 36 inches. Depth to Cr horizon, which is usually present, ranges from 20 to 40 inches. Depth to hard bedrock ranges from 40 to 60 inches. Rock fragments of basalt gravel from 0 to 35 percent in the A horizon, from 35 to 55 percent in the B horizon and 35 to 90 percent in the C horizon. Angular basalt cobbles range from 0 to 15 percent in the solum. This soil is very strongly acid or strongly acid in the A horizon, unless limed, and moderately acid through neutral in the lower B and C horizons.
The Ap horizon has hue of 7.5YR or 10YR, value of 4 or 5 and chroma of 3 through 6.
The thin A horizon, where present, has hue of 7.5YR or 10YR, or neutral, value of 2 or 3 and chroma of 0 through 6. The A horizon is loam or silt loam in the fine earth fraction.
The E horizon, where present, has hue of 7.5YR or 10YR, value of 4 through 6 and chroma of 3 through 6. It is loam or silt loam in the fine earth fraction.
The Bt horizon has hue of 5YR, 7.5YR, or 10YR, value of 5 or 6 and chroma of 4 through 8. Redder mottling is common in some pedons. It is loam, clay loam, or silty clay loam in the fine earth fraction.
The C horizon is variegated in shades of yellow, olive, brown, red and white. It is sandy loam, silt loam or loam in the fine earth fraction.
Some pedons may contain a thin Cr horizon of partially weathered basalt or diabase.
COMPETING SERIES: These are the Conotton, Dorerton, Hawksbill, Leoni, and Lutzke. Conotton soils are formed in stratified sandy and gravelly materials and have a solum from 40 to 80 inches thick. The Dorerton soils have free carbonates from 16 to 45 inches deep and limestone rock fragments in the lower part of the solum. Hawksbill soils are more than 6 feet to bedrock and have greenstone, sandstone and phyllite rock fragments. Leoni and Lutzke soils are formed in stratified outwash plains and have free carbonates in some part of the solum.
GEOGRAPHIC SETTING: Oakhill soils are on ridges and side slopes on diabase dykes and basalt flows in the Culpeper Basin. These soils developed in residuum that weathered from diabase and basalt. Slopes range from 2 to 35 percent. Mean annual precipitation ranges from 36 to 44 inches and mean annual temperature ranges from 52 to 59 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Jackland, Legore, Montalto, Oatlands and Sudley soils. The Jackland soils have very plastic clay subsoils. The Legore soils have bedrock more than 60 inches deep. The Montalto soils have red clay subsoils. The Oakland and Sudley soils have rock fragments of Triassic-Jurassic sandstone and conglomerates.
DRAINAGE AND PERMEABILITY: Well drained, medium surface runoff; moderate permeability.
USE AND VEGETATION: Used for the general crops, pasture and hay. Few areas are used for residential and commercial development. Woodland vegetation is dominantly oak-hickory type forest.
DISTRIBUTION AND EXTENT: Northern Virginia and Maryland. The series is of moderate extent. Approximately 10,000 acres in Northern Virginia.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Prince William County, Virginia 1985.
REMARKS: This soil has previously been included with Legore soils. The Legore soils are fine loamy and more than 60 inches to bedrock. Lab data from VPI & SU Lab.
REVISED = 2/18/2004, MAV added active ce activity class.
1/2005 - revised OSD to show R at 34" rather than 45" since this material was dug with a backhoe.
Diagnostic horizons and features recognized in this pedon are:
a) Ochric epipedon - the zone from the surface down to 8 inches (Ap horizon).
b) Argillic horizon - the zone from 8 to 25 inches (Bt horizon)
c) Lithic contact - at 34 inches (R horizon).
SIR#s VA0055, VA0234
MLRA 148