LOCATION BLOCKTOWN MDEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, semiactive, mesic, shallow Typic Hapludults
TYPICAL PEDON: Blocktown channery silt loam in a cultivated area on a 2 to 8 percent side slope. (Colors are for moist soil.)
Ap--0 to 6 inches; yellowish red (5YR 4/6) channery silt loam; moderate medium granular structure; friable; many fine roots; 30 percent rock fragments; slightly acid; abrupt smooth boundary. (2 to 10 inches thick.)
Bt--6 to 17 inches; red (2.5YR 4/6) very channery silt loam; weak medium granular structure; friable; thick clay skins in pores and on ped faces; few fine roots; 60 percent rock fragments; slightly acid; abrupt wavy boundary.
Cr--17 to 21 inches; variegated red (2.5YR 4/6) and yellowish red (5YR 5/6) soft bedrock that crushes to extremely channery silt loam; inherited rock structure; firm; 90 percent rock fragments; strongly acid; clear wavy boundary.
R--21 inches; hard phyllite bedrock.
TYPE LOCATION: Montgomery County, Maryland; 1 mi. south of Woodfield, about 1,510 feet north on Log House Road from the intersection of Watkins Road, then 2,265 feet east in cultivated field.
RANGE IN CHARACTERISTICS: The thickness of the solum ranges from 10 to 20 inches. Depth to the Cr horizon ranges from 10 to 20 inches, and the depth to hard bedrock ranges from 20 to 40 inches. Rock fragments of veined quartz and phyllite range from 15 to 50 percent in the A horizon, and from 35 to 90 percent in the B and C horizons. The fine- earth fraction of the textural control section has greater than 50 percent silt and very fine sand. Soil reaction ranges from medium acid to slightly acid if not limed.
The A or Ap horizon has hue of 2.5Y through 2.5YR, value of 3 through 5 and chroma of 4 or 6. It is silt loam or loam in the fine-earth fraction.
The E horizon, where present, has hue of 10YR through 2.5YR, value of 3 through 5, and chroma of 3 or 4. It is silt loam or loam in the fine- earth fraction.
The Bt horizon has hue of 10YR through 10R, value of 3 through 5, and chroma of 3 through 8. It is silt loam, loam, or silty clay loam in the fine-earth fraction.
The C horizon, where present, has hue of 7.5YR through 2.5YR, value of 3 through 5, and chroma of 4 through 8. It is silt loam or loam in the fine-earth fraction.
The Cr (bedrock) horizon can be dug with hand tools; the R (hard bedrock) horizon cannot be dug with hand tools.
COMPETING SERIES: There are no competing series in this family.
GEOGRAPHIC SETTING: Blocktown soils are on narrow ridge crests and side slopes of dissected landscapes in the Piedmont Plateau. Slopes range from 0 to 60 percent. The soils formed in residuum of weathered beds of phyllite. 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 Brinklow soils and the Glenville and Linganore soils. The Brandywine, Chester, Glenelg, Manor, Mt. Airy, and Occoquan soils are on nearby landscapes. All of these soils are greater than 20 inches to bedrock. Brinklow and Occoquan soils are on broader ridges and lower segments of side slopes. Glenville soils are around the heads of drainageways and have a fragipan.
DRAINAGE AND PERMEABILITY: Well drained; medium to very rapid runoff; moderate permeability.
USE AND VEGETATION: Most of this soil is cropped to corn, small grain, soybeans and hay. A moderate amount is in pasture and woodland. Forested areas consist of black oak, white oak, red oak, hickory, Virginia pine and yellow poplar.
DISTRIBUTION AND EXTENT: The Piedmont Plateau of Maryland and possibly Pennsylvania and Virginia. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Montgomery County, Maryland; 1989.
REMARKS: The Blocktown series has previously been included in the Linganore, Urbana, Chester, Glenelg, and Manor series. The Linganore series is moderately deep, Urbana soils are classified as Aquic Fragiudalfs, and Chester, Glenelg, and Manor soils are very deep and are developed from micaceous schist.
Diagnostic horizons and features recognized in this pedon are:
a. Ochric epipedon - the zone from the surface of the soil to a depth of 6 inches (Ap horizon).
b. Argillic horizon - the zone from 6 to 17 inches (Bt horizon).
c. Paralithic contact - the zone from 17 to 21 inches (Cr horizon).
d. Lithic contact - at 21 inches (R horizon).
Additional data: Laboratory data are not available at this time.