LOCATION RAPIDAN VAEstablished Series
TAXONOMIC CLASS: Fine, mixed, semiactive, mesic Typic Hapludults
TYPICAL PEDON: Rapidan loam on a west facing slope in row crops at 450 feet elevation. (Colors are for moist color unless otherwise stated)
Ap--0 to 8 inches; dark yellowish brown (10YR 4/4) loam, yellowish brown (10YR 5/4), dry; weak medium subangular blocky structure; friable, slightly sticky, nonplastic; common fine roots and few medium roots; few fine tubular pores; 5 percent rounded 6- to 19-millimeter metaquartzite fragments; strongly acid; clear smooth boundary.
Bt1--8 to 16 inches; reddish brown (5YR 5/4) silty clay loam; moderate coarse subangular blocky structure; friable, slightly sticky, slightly plastic; few fine roots; common fine tubular and common medium tubular pores; 40 percent discontinuous distinct reddish brown (5YR 5/4), moist, clay films on all faces of peds; 7 percent subrounded 6- to 19- millimeter metaquartzite fragments; very strongly acid; gradual wavy boundary.
Bt2--16 to 26 inches; reddish brown (2.5YR 4/4) clay; weak very coarse angular blocky structure parting to moderate medium subangular blocky structure; firm, moderately sticky, moderately plastic; few fine roots; few fine tubular pores; 60 percent continuous prominent reddish brown (2.5YR 4/4), moist, clay films on all faces of peds; 7 percent subrounded 6- to 19-millimeter metaquartzite fragments; very strongly acid; gradual wavy boundary.
Bt3--26 to 48 inches; reddish brown (2.5YR 4/4) clay; weak very coarse angular blocky structure parting to moderate medium subangular blocky structure; firm, moderately sticky, moderately plastic; few fine roots; few fine tubular pores; 80 percent continuous prominent reddish brown (2.5YR 4/4), moist, clay films on all faces of peds; very strongly acid; gradual wavy boundary.
Bt4--48 to 80 inches; reddish brown (2.5YR 4/4) silty clay loam; common medium prominent strong brown (7.5YR 5/8) mottles; weak medium angular blocky structure; friable, slightly sticky, slightly plastic; 50 percent discontinuous distinct reddish brown (2.5YR 4/4), moist, clay films on all faces of peds; very strongly acid.
TYPE LOCATION: Culpeper County, Virginia. USGS Culpeper West topographic quadrangle; lat. 38 degrees 24 minutes 54.67 seconds N. and long. 78 degrees 2 minutes 16.69 seconds W; NAD83.
RANGE IN CHARACTERISTICS: The depth to the base of the argillic horizon ranges from 40 to greater than 60 inches. The depth to paralithic or lithic contact is greater than 60 inches. Reaction is strongly acid through neutral thoughout.
Some pedons have an A horizon with hue of 2.5YR to 7.5YR, value of 2 to 4, and chroma of 2 to 4. It is loam, silt loam, clay loam or silty clay loam. Rock fragments content ranges from 0 to 15 percent. It is mainly medium and coarse conglomerate gravels.
The Ap horizon has hue of 10R to 5YR, value of 2 to 4, and chroma of 2 or 4. It is loam, silt loam, clay loam or silty clay loam. Rock fragments content ranges from 0 to 30 percent. It is mainly medium and coarse metaquartzite and conglomerate gravels.
The Bt horizon has hue of 10R to 5YR, or is variegated 2.5YR to 10YR; value of 3 to 5, or variegated 2 to 8; and chroma of 4 to 8, or variegated 1 to 8. It is clay loam, silty clay loam, clay or silty clay. Rock fragments content ranges from 0 to 30 percent. It is mainly medium and coarse conglomerate gravels and conglomerate cobbles
Some pedons have a BC horizon with hue of 2.5YR to 5YR, or variegated 5YR to 10YR; value of 4, or variegated 2 to 6; and chroma of 4, or variegated 1 to 8. It is loam, silt loam, silty clay loam or clay loam. Rock fragments content ranges from 0 to 50 percent. It is mainly medium and coarse conglomerate gravels.
Some pedons have a C horizon with hue of 2.5YR, or variegated 10R to 10YR and neutral; value of 3 or 4, or variegated 2 through 8; and chroma of 4, or variegated 0 to 8. It is loam or silt loam. Rock fragment content is 0 percent.
COMPETING SERIES: Boden, Braddock. Buffstat, Casville, Christian, Clifton, Clover, Danripple, Flagspring, Goresville, Groseclose, Howell, Mount Rush, Muse, Sequoia, Spears Mountain, Totier, Unison, Warminster and Yellowbottom are competing series. Mount Rush, Sequoia, and Spears Mountain have lithic or paralithic contact between 20 and 40 inches. Mount Rush soils developed in residuum of mixed felsic and mafic metamorphic and igneous rock. Sequoia developed in residuum of red shale and siltstone. Spears Mountain soils developed in residuum of schist, phyllite and other fine-grained rock. Boden, Buffstat, Christian, Howell, Muse, Totier and Warminster have lithic or paralithic contact between 40 and 60 inches. Boden soils developed in residuum of sandstone and shale in the Ozark Highlands. Buffstat soils developed in residuum of sericite schist, graphitic schist or phyllite. Christian soil developed in residuum of interbedded limestone, sandstone, siltstone, and shale. Howell soils developed in unconsolidated sediments containing diatomaceous earth or glauconite. Muse soils developed in colluvium of shale and siltstone. Totier and Warminster soils developed in red Triassic shale. Danripple soils are moderately well drained and developed in alluvium on high stream terraces. Braddock soils developed in colluvium and alluvium of crystalline rock. Casville soils developed in residuum of felsic or intermediate igneous or metamorphic rock. Clifton soils developed in residuum of intermediate and mafic rock. Clover soils developed in residuum of Triassic materials. Flagspring soils developed in colluvium of cherty limestone over residuum of limestone and Tripoli. Goresville soils developed in alluvium on high stream terraces. Groseclose soils developed in residuum of limestone, shale, siltstone, and sandstone. Unison soils developed in colluvium and alluvium of mixed acidic and basic crystalline rock. Yellowbottom soils developed in residuum of sericite schist, phyllonite or metamonzagranite.
GEOGRAPHIC SETTING: Rapidan soils formed in greenstone conglomerate and are on summits, shoulders and backslopes of ridges in the Culpeper Jurassic-Triassic Basin of the Northern Piedmont. Slope gradients ranges from 2 to 45 percent. The mean annual temperature ranges from 50 to 58 degrees F and the mean annual precipitation ranges from 38 to 48 inches, frost free days range from 165 to 203 days and elevation ranges from 150 to 850 feet above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Albano, Clover, Dulles, Nestoria, Penn soils. Albano soils are poorly drained and in drainageways. Clover is on similar landforms but developed in residuum of siltstone. Nestoria and Penn are on similar landforms but are shallower to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; potential for surface runoff medium to high; moderate permeability.
USE AND VEGETATION: Rapidan soils are used for cropland, pastureland, hayland and woodland. The principal crops are corn, small grain, and hay. Forest vegetation consists of white, scarlet, red, post and chestnut oaks, shortleaf pine, Virginia pine, and a few hickory, dogwood, and black gum.
DISTRIBUTION AND EXTENT: MLRA 148. Culpeper Jurassic-Triassic Basin of the Northern Piedmont in Virginia. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Culpeper County, Virginia, 1948.
REMARKS: 6/2004--Rapidan type location moved to Culpeper County, Virginia due to age of original description and errors within description. Classification was changed from Clayey, mixed, mesic, Typic Rhodudults because it is thought that rhodic colors are on the fringe rather than the central concept of this series.
Diagnostic horizons and features recognized in this pedon are:
1) Ochric epipedon - from 0 to 8 inches (Ap horizon)
2) Argillic horizon - from 8 to 80 inches (Bt horizons).