LOCATION RAVENROCK MDEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, active, mesic Ultic Hapludalfs
TYPICAL PEDON: Ravenrock gravelly silt loam, on a south facing, smooth, 18 percent slope, very bouldery, under a mixed hardwood forest at an elevation of 1,260 feet. (Colors are for moist soil).
A----0 to 4 inches; brown or brown (7.5YR 4/4) gravelly silt loam; moderate very fine subangular blocky structure; friable; many medium roots, 30 percent pebbles; slightly acid; clear wavy boundary. (2 to 10 inches thick)
BE----4 to 7 inches; strong brown (7.5YR 4/6) gravelly silt loam; moderate very fine subangular blocky structure; friable; common fine and medium roots; common very fine tubular pores; 25 percent pebbles; moderately acid; gradual wavy boundary. (0-10 inches thick)
Btl---7 to 16 inches; yellowish red (5YR 4/6) gravelly silt loam; moderate very fine subangular blocky structure; friable; many medium and coarse roots; common very fine tubular pores; many distinct clay films on faces of peds and lining pores; 30 percent pebbles; strongly acid; clear wavy boundary.
Bt2---16 to 34 inches; yellowish red (5YR 4/6) very gravelly clay loam; moderate medium subangular blocky structure; friable; common fine roots; common very fine tubular pores; many distinct clay films on faces of peds and lining pores; 40 percent pebbles; strongly acid; abrupt wavy boundary. (Combined thickness of the Bt horizon is 8 to 30 inches).
2Bt3---34 to 43 inches; red (2.5YR 4/6) very cobbly clay loam; weak fine platy structure; firm; few fine roots; common very fine tubular pores; many distinct clay films on faces of peds and lining pores; 25 percent pebbles and 30 percent cobbles; moderately acid; abrupt wavy boundary.
2Bt4---43 to 57 inches; red (2.5YR 4/8) gravelly silty clay; moderate medium angular blocky structure; friable; many medium roots; few very fine vesicular pores; many distinct clay films on faces of peds and lining pores; 15 percent pebbles; strongly acid; abrupt irregular boundary. (Combined thickness of the 2Bt 20 to 45inches).
2C---57 to 65 inches; red (2.5YR 4/6) gravelly clay loam; massive; firm; many fine roots; few very fine vesicular pores; 25 percent pebbles; common distinct yellowish red (5YR 5/6) iron stains; strongly acid; abrupt irregular boundary. (0 to 25 inches thick)
3Cr---65 to 80 inches; olive brown (2.5Y 4/4) fine sandy loam; massive; very firm; vertical cleavage fractures; cracks with inter-finger of Bt/C material; strongly acid.
TYPE LOCATION: Frederick County, Maryland; located in William Houck Area of Cunningham Falls State Park about 200 feet south of water treatment plant; Blue Ridge Summit topographic quadrangle; lat. 39 degrees 37 minutes 37 seconds N. and long. 77 degrees 28 minutes W.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 40 to 80 inches or more. Depth to bedrock is greater than 60 inches. Aquic conditions and redoximorphic features in some pedons are below a depth of 40 inches. Rock fragments range from 1 to 50 percent on and in the surface, 15 to 70 percent in individual subsoil and substratum horizons with a weighted average of greater than 35 percent in the upper 20 inches of the argillic horizon. Rock outcrops of metabasalt commonly occur within Ravenrock soil landscapes and occupy from 0 to 25 percent of the surface. Reaction ranges from very strongly acid through slightly acid.
The A horizon has hue of 5YR through 10YR, value of 2 through 4, and chroma of 2 through 4. It is silt loam or loam in the fine earth fraction.
The BE, EB, and/or E horizons where present have hue of 5YR through 10YR, value of 4 through 6, and chroma of 4 or 6.It is silt loam or loam in the fine earth fraction.
The Bt horizon has hue of 5YR through 10YR, value of 4 through 6, and chroma of 4 through B. It is commonly silt loam or loam, but ranges to clay loam in the fine earth fraction.
The 2Bt horizon has hue of 2.5YR through 7.5YR, value of 4 through 6, and chroma of 4 through 8. Redoximorphic features are evident in some pedons. It is commonly clay loam, but ranges from loam to silty clay in the fine earth fraction.
The 2BC and 2C horizons, where present, have hue of 2.5YR through 2.5Y, value of 4 through 6, and chroma of 4 through 8. It is sandy loam, loam, silt loam, or clay loam in the fine earth fraction.
COMPETING SERIES: These are the Lew, Linganore and Neotoma series. Lew soils do not have redoximorphic features or aquic conditions in the lower part of the Bt horizon. Linganore soils are less than 40 inches to a paralithic contact. Neotoma soils have rock fragments dominated by siltstone or sandstone and depth to bedrock is 60 inches or less.
GEOGRAPHIC SETTING: Ravenrock soils are on tread-riser backslopes and footslopes in the Blue Ridge Mountains. Slope is commonly 8 to 45 percent but ranges from 0 to 65percent. These soils are generally stony, very stony, extremely stony or bouldery and commonly occur with 0 to 25 percent rock outcrops of metabasalt. Ravenrock soils formed in colluvium and/or soil creep derived from metabasalt (greenstone) and metarhyolite. Mean annual temperature ranges from 50 to 57 degrees F., and mean annual precipitation ranges from 38 to 44 inches. Elevations are 800 to 2,000 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Bagtown, Catoctin, Foxville, Highfield, Lantz, Mt. Zion, Myersville, Rohrersville, Spoolsville, and Weverton soils. Bagtown, Highfield, and Spoolsville soils have less than 18 percent clay in the textural control section. Catoctin soils have a discontinuous argillic horizon and are less than 40 inches to bedrock. Foxville soils have redoximorphic features above 40 inches and are on adjacent floodplains. Lantz, Mt. Zion, Myersville, and Rohrersville soils have less than 35 percent rock fragments in the textural control section. In addition, Lantz and Rohrersville soils occur in swales and drainageways and have redoximorphic features and an aquic condition above a depth of 40 inches.
DRAINAGE AND PERMEABILITY: Well drained with a seasonal water table between a depth of 40 to 72 inches during December through April; medium to high runoff; moderate permeability in the upper part of the solum and moderately slow to slow in the lower part of the solum and substratum.
USE AND VEGETATION: These soils are used for timber production, recreation, water supply, wildlife habitat, and to a limited extent for homesites. Native vegetation is northern red oak, yellow poplar, black gum, ash, red maple, shagbark hickory, and yellow birch. Understory vegetation is spice bush, witch hazel, viburnum, and dogwood.
DISTRIBUTION AND EXTENT: Maryland; possibly Virginia and Pennsylvania. The soils of this series are moderately extensive; their total extent is about 15,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia.
SERIES ESTABLISHED: Frederick County, Maryland, August 1997.The name "Ravenrock" is taken from a county road near the type location.
REMARKS: Diagnostic horizons and features in this pedon included:
1. Ochric epipedon, from a depth of 0 to4 inches (A horizon).
2. Argillic horizon - from a depth of 7 to 57 inches (Btl, Bt2, 2Bt3, and
2Bt4horizons).
3. Aquic condition from a depth of 40 to 72 inches.
Ravenrock soils were formerly included with the Highfield and Fauquier series and the miscellaneous land type of Rough stony land. They were preliminarily considered Lew soils beginning in 1984.
ADDITIONAL DATA: Complete characterization of pedons S84MD021-1, S84MD021-3, and S84MD021-5 from Frederick County, MD by NSSL, Lincoln, NE, 4/86 as part of a USGS study led by C. Olson; detailed pit description (S93MD021-2).