LOCATION DULLES VAEstablished Series
TAXONOMIC CLASS: Fine, vermiculitic, mesic Aquultic Hapludalfs
TYPICAL PEDON: Dulles silt loam - fescue hayfield, on a nearly level head of drainageway with 0 to 2 percent slopes. (Colors are for moist soil.)
Ap--0 to 8 inches; brown (7.5YR 4/4) silt loam; moderate fine granular structure; friable, many fine roots; 1 percent rounded and subrounded quartz gravel up to 2 inches very strongly acid abrupt smooth boundary. (0 to 10 inches thick.)
Bt--8 to 15 inches; yellowish brown (10YR 5/6) silty clay loam; moderate medium and fine subangular blocky structure; firm, sticky, slightly plastic, many fine roots; common thin films of clay on faces of peds; common fine vesicular pores; 1 percent rounded and subrounded quartz gravel up to 2 inches very strongly acid; clear smooth boundary.
Bt2--15 to 22 inches; yellowish brown (10YR 5/6) silty clay loam; few fine and medium light gray (10YR 7/2) mottles; moderate fine and medium subangular blocky structure; firm, plastic, sticky; many fine roots; thin continuous films of clay on faces of peds; common fine vesicular pores; very strongly acid clear; smooth boundary.
Bt3--22 to 34 inches; yellowish brown (10YR 5/8) silty clay; common light brownish gray (10YR 6/2) and gray (10YR 6/1) to light gray (10YR 7/2) mottles and coatings; moderate fine subangular blocky structures; firm, plastic and sticky; few fine roots; thin continuous films of clay and silty coatings on faces of peds; 1 percent rounded quartz gravel up to 2 inches; very strongly acid; clear smooth boundary. (Combined thickness of the Bt horizon ranges from 20 to 45 inches)
2Btg--34 to 39 inches; light brownish gray (10YR 6/2) clay; many coarse prominent gray (10YR 6/1) to light gray (10YR 7/1) bluish gray (5B 6/1) and dark yellowish brown (10YR 3/4) mottles and streaks; moderate coarse subangular blocky structure; firm plastic, sticky; few fine roots; 10 percent weathered red shale channers; very strongly acid clear smooth boundary.
2BtCg--39 to 43 inches; light gray (10YR 7/1) very channery clay; many gray (10YR 6/1) bluish gray (5B 6/1) and reddish brown mottles and streaks; weak medium subangular blocky structure; firm, very plastic, very sticky; many thin and medium films of clay on face of peds. 40 percent weathered red shale channers; very strongly acid abrupt smooth boundary. (Combined thickness of the 2Bt ranges from 8 to 20 inches)
2Cr--43 to 59 inches; red partially weathered shale with gray, pinkish gray and greenish clay coatings on surfaces and in crevices.
R--59 inches; shale bedrock.
TYPE LOCATION: Prince William County, Virginia; in Manassas Battlefield Park; about 1 mile north of Route 29211, about 120 yards west of State Route 234 and about 75 yards north of picnic area road.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 22 to 48 inches. Depth to dense weathered bedrock (Cr horizon) ranges from 40 to 60 inches. Depth to hard red, fine grained sandstone, siltstone or shale bedrock ranges from 40 to 60 inches and is quite variable over short horizontal distances. Coarse fragments of subrounded quartz range from 0 to 5 percent in the A and upper part of the B horizon. Coarse fragments of soft to relatively hard red and reddish-brown, fine grained sandstone, siltstone and shale range from 5 to 50 percent below the lithologic discontinuity. Coarse fragments of hard residual red, fine grained sandstone, siltstone and shale range from 25 to 60 percent in the C horizon where present. The soil is very strongly acid through moderately acid.
The Ap horizon has hue of 7.5YR or 10YR, value of 4 through 6 and chroma of 2 through 6. The Ap horizon is a silt loam. Where present, Al horizons are similar to the Ap horizons.
The Bt horizon has hue of 7.5YR or 10YR, value of 5 through 7 and chroma of 4 through 8. It is silt loam, silty clay loam, silty clay, or clay.
The 2Bt has hue of 10R through 10YR, value of 3 through 5 and chroma of 3 through 8. The texture is silty clay or clay.
The 2Btg or 2BtCg has hue of 10R through 10YR, value of 3 through 6 and chroma of 0 through 2. The texture is silty clay or clay.
In most pedons the B horizon rests directly on a Cr horizon. Where present, C horizons are thin transitional zones of clayey gravel composed of thick weak red, pinkish gray, gray and greenish gray clay flows and variably weathered red siltstone and shale.
COMPETING SERIES: Kelly series is the only soil in the same family. The Kelly soils have chroma of less than 4 in the Bt horizon and are formed from weathered gray shale.
The Iredell and Jackland soils are in closely related families. The Iredell and Jackland soils have montmorillonitic mineralogy.
GEOGRAPHIC SETTING: Dulles soils are on broad nearly level uplands, and concave lowlands such as toeslopes and heads of drainageways in Triassic-Jurassic Basins of the Northern Piedmont Plateau. Slope gradients are typically 0 to 4 percent. The soils formed in slope creep and in residuum from red, fine grained sandstone, siltstone and shale. The source of the colluvium is Pleistocene aged mass wastage of old alluvial cappings and residual red bedrock materials. Elevations range from 180 to 300 ft. The mean annual temperature ranges from 50 to 57 degrees F and mean annual precipitation ranges from 38 to 44 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the poorly drained Albano, Ashburn, Bucks, Penn and Reaville soils. Albano soils are poorly drained. Ashburn soils have a fine-silty control section. Bucks, Penn and Reaville have control sections with dominantly reddish hue.
DRAINAGE AND PERMEABILITY: Moderately well and somewhat poorly drained; slow runoff. The permeability in the upper subsoil is slow, it is very slow in the lower subsoil.
USE AND VEGETATION: Most of this soil is cleared and used for crop land, hay and pasture. Native vegetation is primarily northern red oak, hickory, Virginia pine, shortleaf pine and red maple.
DISTRIBUTION AND EXTENT: Culpeper Basin of Virginia and the southwestern part of the Gettysburg Basin of Pennsylvania and Maryland. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Prince William County, Virginia, 1985.
REMARKS: These soils were formerly mapped with the Kelly series.
ADDITIONAL DATA: Laboratory Data by Virginia Polytechnic Institute and State University.