LOCATION OCCOQUAN VA+MD
Established Series
Rev. DLK-JHE-DDR
01/2022
OCCOQUAN SERIES
Soils of the Occoquan Series are deep, somewhat excessively drained to well drained soils with moderate to rapid permeability. They formed in residuum that weathered from granite gneiss and schist of the Piedmont Plateau. Slopes range from 0 to 50 percent. Mean annual precipitation is about 40 inches and mean annual temperature is about 53 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, semiactive, mesic Inceptic Hapludults
TYPICAL PEDON: Occoquan sandy loam on a 12 percent slope in a mixed hardwood forest. (Colors are for moist soil.)
Oi--0 to 2 inch; partially decomposed hardwood leaves and twigs.
A--2 to 4 inches; dark grayish brown (10YR 4/2) sandy loam; weak fine granular structure; very friable; many fine, medium and coarse roots; 6 percent angular quartz gravel; 1 percent angular cobbles; few fine flakes of mica; extremely acid; clear smooth boundary. (0 to 4 inches thick.)
E--4 to 11 inches; pale brown (10YR 6/3) sandy loam; weak medium and fine granular structure; very friable; many fine and medium roots; 6 percent angular quartz gravel; 1 percent cobbles; few fine flakes of mica; extremely acid; clear smooth boundary. (0 to 10 inches thick.)
Bt--11 to 19 inches; strong brown (7.5YR 5/8) loam; common fine and medium distinct brownish yellow (10YR 6/6) and yellowish red (5YR 5/8) mottles; weak fine and medium subangular blocky structure; friable; many fine, medium and coarse roots; common distinct patchy clay films on faces of peds; common fine flakes of mica; 3 percent angular quartz gravel; extremely acid; clear smooth boundary. (6 to 10 inches thick.)
C--19 to 55 inches; multicolored in shades of brown, yellow, red and white sandy loam saprolite; massive; very friable; common fine roots; few thin flows of clay in the upper 20 inches; common fine flakes of mica; 3 percent angular quartz gravel; very strongly acid; clear irregular boundary. (26 to 50 inches.)
Cr--55 to 74 inches; partially weathered granite gneiss that crushes to sandy loam; tongues of the C horizon.
TYPE LOCATION: Prince William County, Virginia, 2 miles northeast of Route 663, 450 feet south of Occoquan Club Drive in Occuquan Club Subdivision.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 12 to 24 inches. Depth to soft bedrock ranges from 40 to 60 inches. Depth to hard bedrock is more than 60 inches. Angular vein quartz fragments range from 0 to 15 percent throughout the soil. Few to many flakes of mica are in the B and C horizons. Reaction is extremely acid through strongly acid unless limed.
The A horizon have hue of 10YR or 2.5Y, value of 4 through 7 and chroma of 2 through 4. The A horizon is loam, sandy loam, or coarse sandy loam.
The E horizon has hue of 10YR or 2.5Y, value of 5 through 7 and chroma of 3 or 4. It is loam, sandy loam or coarse sandy loam.
The Bt horizon has hue of 5YR through 10YR, value of 5 or 6 and chroma of 4 through 8. It is loam, sandy loam, sandy clay loam or clay loam.
The C horizon is multicolored in shades of red, yellow, brown and white. It is loam, sandy loam or loamy sand saprolite.
The Cr horizon is multicolored in shades of red, yellow, brown and white. It is partially weathered granite gneiss and/or schist that crushes to loam, sandy loam, or loamy sand.
COMPETING SERIES: There are no competing series in the same family.
GEOGRAPHIC SETTING: Occoquan soils are on summits, shoulders, and sideslopes of narrow ridges in the Northern part of the Piedmont Plateau. Slope gradients ranges from 0 to 50 percent. These soils are underlain by granite gneiss and schist. Mean annual precipitation ranges from 36 to 44 inches and mean annual temperature ranges from 50 to 57 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Baile,
Buckhall,
Fairfax,
Glenelg, Hoadley and
Meadowville soils. The poorly drained Baile, the somewhat poorly drained
Hoadly and the moderately well to well drained Meadowville soils are on lower positions in the landscape and are subject to seepage and runoff from the soils on adjacent higher landscape positions. The Fairfax soil is developed partly in coastal plains sediments and partly in residuum from mica schist and gneiss and has a higher clay content in the control section. The Glenelg soil developed in mica schist and has a thicker solum.
DRAINAGE AND PERMEABILILTY: Well drained to somewhat excessively drained; medium surface runoff; moderate to moderately rapid permeability.
USE AND VEGETATION: Largest acreage is in pine and hardwood forest. Few small areas are used for residential developments and few small areas are in pasture. Some of the native vegetation consists of Virginia Pine, Chestnut Oak, White Oak, Northern Red Oak and Yellow Popular.
DISTRIBUTION AND EXTENT: Northern Virginia and Maryland. Large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Prince William County, Virginia, 1985.
REMARKS: The Occoquan series has previously been included in the Louisburg series. Which is thermic and classified coarse-loam, mixed, thermic Ruptic-Ultic Dystrochrepts.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon-the zone from 2 to 11 inches (A and E horizons) Argillic horizon-the zone from 11 to 19 inches (Bt horizon less than 10 inches thick)
11/2021 revision: Oi had 2 to 0 inch depths, corrected to be 0 to 2 in horizon depths then added 2 inches to all horizon depths throughout the typical pedon.
SIR = VA0192, VA0328 (VERY STONY)
MLRA = 148
REVISED = 8/30/90
National Cooperative Soil Survey
U.S.A.