Virginia Open File Report 10-05 Department of Surficial Geologic Map of the Elkton West Quadrangle, Virginia Mines, Minerals and Energy Virginia Division of Geology and Mineral Resources SURFICIAL GEOLOGIC MAP OF THE ELKTON WEST QUADRANGLE, VIRGINIA

(BROADWAY MATTHEW J. HELLER AND L. SCOTT EATON ) 2010 ) (STANLEY DESCRIPTION OF MAP UNITS 78° 45’ (TENTH LEGION) 78° 37’ 30’’ 38° 30’ 38° 30’ Modified land – Area of extensive cut and/or fill related to site development. Qrcc Qal ml Qrcc Qrcl Qdf1 Qdf Qdf Qdf Qdf3 3 Qt2 Qal Qdf 1 3 Qrcl Qrcl 2 Qdf3 Qrs Qdf Alluvial channel and flood plain deposits – Alluvial channel: unconsolidated , , Qdf1 Qrcl 3 Qal Qdf Qdf3 303 Qdf1 Qrs 1 Qrs sand, gravel, cobbles, and boulders. Composition, color, grain size, rounding, and sorting Qdf3 ml Qrcc Qdf3 Qrcc are variable. Streams that drain terrace and debris-flow deposits contain material that is Qrcl Qrcl reworked from the older deposits. Alluvial flood plain deposits: overbank deposits of clay, Qrcc Qrcl Qt Qal Qdf Qdf3 1 Qdf 3 Qdf2 Qdf3 Qdf1 Qt silt, sand, and minor cobbles within active flood plains. Subject to frequent flooding. 1 Qdf1 2 Qdf3 Qdf Qrcl Qdf1 3 Qrs Qrcl Qrcc Ridge and upper slope deposits – Thin, tan loamy sand residual on mountain ridge Qdf Qdf Qrs Qrcc 3 Qdf 3 tops, discontinuous quartzite and quartz outcrop on ridge tops, in water gaps, 3 Qrcc Qrcc Qrs Qdf3 Qdf and on outcrop slopes, and clast-supported blocks and boulders in a tan-to-brown loamy 2 Qdf3 Qdf1 Qdf2 Qdf Qdf Qt sand matrix on outcrop and dip slopes. Loose material occurs as block slopes, landslides, Qdf Qdf 3 Qdf 3 2 2 Qdf 1 1 Qrcl and talus on slopes greater than 15 degrees. Up to 20 feet (6 meters) thick. 1 Qrs Qdf3 Qdf3 ml Qdf3 Qrcl Qrcl Qdf Younger terrace deposits – Unconsolidated clay, silt, sand, gravel and cobbles. Cobbles 1 Qt1 Qt2 are mostly quartzite and quartz sandstone with minor amounts of metamorphosed Qt1 Qdf3 Qdf3 Qrcc Qdf2 Qrcc sedimentary rock. Deposits are clast-supported in a brown to red-brown clay loam to Qrcl Qdf3 Qdf3 Qdf2 loamy sand matrix; clay content and red color increase with elevation above river level. Qrs Qrs Qrcl Qdf1 Qdf3 Cobbles commonly form a cap at land surface and are interlayered with sand-to-clay loam Qrcl Qdf1 Qdf Qal fines at depth. Terrace deposits occur at elevations from 10 to 75 feet (3 to 23 meters) Qrcc Qdf 3 Qdf1 3 Qdf3 Qdf Qrs above the flood plain and are up to 30+ feet (9+ meters) thick. Terraces are commonly 3 Qdf3 Qrcc Qdf3 Qrcl Qdf modified by karst in areas underlain by carbonate , and/or disturbed by Qdf 3 Qdf3 3 agricultural practices. Lower terraces are subject to infrequent flooding. Qrs Qdf3 Qdf Qdf3 Qrcc 1 Boulder streams and youngest debris-flow deposits – Blocks, boulders, and cobbles of Qrcc Qdf Qal 3 Qdf1 quartzite and quartz sandstone. Clasts of other bedrock may also be present. Very poorly Qdf2 Qrcl Qdf3 Qdf1 sorted. Boulder streams are typically clast-supported and have little or no matrix. Qrcc Qrcl Qdf1 Qdf Debris-flow deposits are supported in a tan-to-brown loamy sand matrix. Boulder streams 1 Qdf1 Qdf Qrcl 3 occur on steep-sided slopes and often have small streams developed along their flanks. Qrcl Qdf1 Qt Debris-flow deposits occur along the margins of active stream channels draining steep, Qdf3 2 Qdf3 mountainous terrain, and as small fans at the base of slopes. Where channels are narrow, Qdf3 Qdf2 the widths of some deposits are exaggerated for illustrative purposes. Some deposits are Qdf Qdf3 Qrcc 3 Qrcl Qrcc discontinuous. Up to 20 feet (6 meters) thick. Qdf 1 Qdf1 Qdf4 Qdf3 Qdf3 Qdf3 Younger debris-flow and associated deposits – Boulders and cobbles of quartzite and Qdf Qdf4 Qdf2 Qrcl Qdf1 Qal 4 quartz sandstone. Weathered clasts of other bedrock may also be present. Very poorly Qdf Qrcl Qdf1 Qdf3 3 Qdf sorted and supported in a tan-to-brown sandy loam to clay loam matrix. Deposits occur as Qrcc Qdf1 Qdf3 3 Qdf3 Qdf3 discontinuous terraces 10 to 40 feet (3 to 12 m) above active stream channels, as small Qdf Qrcc Qdf3 1 fans at the base of slopes, and as a large fan downslope from Harshberger Gap. Highest Qal Qdf3 Qal terraces could be equivalent to Qdf3 deposits. Up to 40+ feet (12+ meters) thick. Qrcl Qrs Qrcl Qrcc Qrcl Qrs Older debris-flow and associated deposits – Boulders and cobbles of quartzite and Qdf Qdf4 3 Qdf3 Qdf Qrs Qdf quartz sandstone. Quartz sandstone clasts are commonly friable. Highly weathered clasts Qdf 1 3 3 Qt of other bedrock may also be present. Very poorly sorted and supported in a tan to Qdf2 2 Qrcl Qdf3 Qdf red-brown sandy loam to clay loam matrix. Deposits are commonly dissected and occur Qrcc 1 Qrcl Qdf Qdf1 3 on ridges and hill tops 40+ feet (12+ meters) above active drainages. Some deposits are Qrcl Qdf1 Qdf4 Qdf3 Qdf3 erosional remnants. Up to 40+ feet (12+ meters) thick. Qdf3 Qdf3 Qdf3 Qal Qrs Qdf4 Qdf3 Qal Oldest debris-flow and associated deposits – Boulders and cobbles of quartzite and Qdf Qrcl Qdf2 Qrcc Qdf 2 Qrcl Qdf1 Qrcc 4 quartz sandstone. Quartz sandstone clasts are friable. Very poorly sorted and supported in Qdf3 Qt2 Qdf1 a red-brown clay loam matrix. Occur as intact surfaces or erosional remnants on hill tops ml Qt1 Qdf3 Qdf Qrcl at elevations as much as 300 feet (90 meters) above active drainages. Some Qdf deposits Qrcl 1 Qdf3 Qdf Qdf1 4 1 Qrcl Qrs Qal Qrcc are mantled by extensive colluvium. This colluvium is distinct from colluvium derived Qrcl Qdf3 from residuum and occurs at lower elevations than Qdf deposits; for mapping purposes, it Qdf3 Qdf2 Qrcl 4 Qdf Qdf3 Qrcl 2 is included in the Qdf map unit. A large fan deposit is present downslope of Runkles Qdf Qdf2 Qdf2 4 3 Qdf Qdf Qdf3 1 Qdf 4 Qt Gap. The toe of this deposit, identified by a stippled pattern, contains cobbles and Qrs 3 Qrcc 2 Qdf1 Qdf Qdf boulders of Antietam quartzite that appear to be reworked from older Qt2 terrace deposits. Qdf2 3 3 Qdf4 Qdf Qrcl Intact cappings on Piney Mountain and a second ridge 4,000 feet (1,200 meters) to the 1 Qrcl Qt1 Qdf Qdf Qdf north may be older than other Qdf4 deposits and Qt2 terraces. Up to 40+ feet (12+ meters) 3 3 4 Qdf4 Qrcl Qdf Qdf 3 2 Qdf1 Qrcc Qt thick. Qdf1 2 Qdf1 Qdf3 Older terrace deposits – Unconsolidated clay, silt, sand, gravel and cobbles. Cobbles are Qdf Qt 1 Qdf2 2 mostly quartzite and quartz sandstone with minor amounts of metamorphosed sedimentary Qdf2 Qdf3 rock. Quartz sandstone clasts are commonly friable. Deposits are clast-supported in a Qdf3 Qrcc Qrs Qdf3 Qal Qt1 Qdf1 Qrs Qal red-brown to red, clay loam to loamy sand matrix; clay content and red color increase with Qdf3 Qdf3 Qdf Qrcl Qrcl 3 Qdf1 Qrcl elevation above river level. Cobbles commonly form a cap at land surface, and are Qrcl Qdf interlayered with sandy silt to clay loam at depth. High terrace deposits occur at 3 Qrcl Qrcl ) Qdf3 Qt elevations from 75 feet to as much as 170 feet (23 to 52 meters) above the current flood Qdf Qdf3 2 ( Qdf 1 Qrcl ELKTON EAST 3 Qrcc plain. Terraces are commonly modified by karst in areas underlain by carbonate bedrock, Qdf4 Qrs Qdf1 and/or disturbed by agricultural practices. Up to 30+ feet (9+ meters) thick. Qdf Qdf 3 3 Qdf1 Qdf3 Qdf Qal Qdf 4 Residuum and colluvium derived from clastic bedrock – Tan to orange-brown sandy Qdf 3 Qdf Qdf3 1 3 Qrcc Qrcl Qdf3 loam to silty clay residual and colluvial soil derived from the weathering of parent Qdf ) HARRISONBURG 3 Qrcl ( material consisting of shale, siltstone, and lithic sandstone. Colluvial soil is present on Qdf3 Qrs Qdf4 Qt1 Qdf Qrcl Qal some slopes and may contain angular fragments of parent material. Rock outcrops are 2 Qdf Qdf1 Qdf Qdf2 3 1 Qrcl Qdf1 intermittent and more common in resistant rocks and along streams. Typically less than Qdf1 Qdf3 Qdf3 Qdf2 Qdf3 Qdf Qdf3 5-10 feet (1.5 to 3 meters) thick. Qdf 3 Qdf Qal 3 Qdf3 2 Qrs Qdf3 Qrcl Residuum and colluvium derived from carbonate bedrock – Brown to orange-brown Qrcl Qrcc Qrcc Qdf clayey loam to clay residual and colluvial soil derived from the weathering of parent Qrcl 3 Qdf3 Qdf 1 Qt1 material consisting of , dolostone, and calcareous shale. Colluvial soil is present Qdf3 Qal Qdf3 on some slopes and may contain angular fragments of parent material. Rock outcrops are Qdf3 Qrcc Qdf4 intermittent and more common in resistant rocks, on outcrop slopes, and along streams. Qrs Qdf1 Qrcl Areas underlain by carbonate bedrock have been variably modified by karst. Thickness is Qdf4 Qdf3 variable and ranges up to 50+ feet (15+ meters). Qdf2 Qdf3 Qal Qt1 Qdf3 Qdf Qdf3 3 MAP SYMBOLS Qdf3 Qdf3 Qal Qrcc Qdf1 Qrcc Qal Contact – approximate Qrs Qrs Qdf3 Qdf4 Qdf3 Observation point Qdf1 Qdf Qal Qal Qdf3 3 Qdf3 Qrcc Qdf3 Qal Qrcl Cut exposing surficial deposits Qt1 Qdf3 Qrcc Qdf Qdf Qrcl Qal Qt2 Soil test pit Qdf1 3 3 Qrcl Qdf1 Soil boring Qdf3 Qdf Qal 3 Qdf4 Spring Qrcl Qdf1 Qrcc Qdf1 Qrcc Abandoned sand and gravel pit – identification numbers are Qt2 Qdf3 Qrcc preceded by “187B-” in Mineral Resources of Virginia database Qdf Qdf Qal 1 Qdf 3 Qrcc Qrcc Painters 3 Qdf3 Pond Qrcl Qdf1 Qrcl Qdf3 Qrcl 903 ml Qdf2 Qal METHODOLOGY Qdf3 Qdf3 Qdf3 Qdf3 Qdf4 ml Qdf1 This map was created primarily using data collected during bedrock geologic mapping of Qdf2 ml Qrcc Qdf4 Qrcc the Elkton West quadrangle (Heller, 2010). Supplemental data were collected in areas of Qrcl Qal Qrcc Qt1 Qrcc extensive or thick surficial deposits, particularly in the southeastern part of the quadrangle. Qrs Qdf Qrcl Qdf3 1 The contact between residuum derived from carbonate and clastic bedrock was placed at Qdf4 Qt Qdf4 2 the bedrock contact of the lower and upper parts of the Martinsburg formation. A digital Qt1 Qdf4 terrain model (DTM) created from elevation control points for VGIN aerial imagery flown Qal Qt2 Qt2 in 2007 and the Soil Survey of Rockingham County (USDA, 1982) were used in Qdf Qdf2 1 Qrcc conjunction with field data to map the extent of each surficial deposit. Some Qdf Qrcl Qdf4 Qrcc 1 ml ml Qdf3 904 deposits were too narrow to be resolved on the DTM and are mapped on the basis of limited field data. A few Qdf1 deposits are inferred based on slope position and drainage Qdf4 source area. As a result, Qdf deposits may be discontinuous or absent in some places. Qdf4 1 Qt2 Qrcc Qdf1 Qt2 Qdf4 Qdf1 ACKNOWLEDGEMENTS Qrcc Qal Qdf3 Qrcc Qt1 This map was prepared in cooperation with the U.S. Geological Survey under Qdf2 Qt1 Qrcl STATEMAP grant award 05HHQAG0088 and 07HQAG0088. Steve Whitmeyer, Holly Qt2 Qal Qal Qdf4 Polivka, Elizabeth Weisbrot, Aaron Cross, Cullen Sherwood, David Dean, and Mike Qt2 Qrcc Qal Enomoto provided field assistance. Greg Hancock, Aaron Cross, Lorrie Coiner, and Qal Chelsea Feeney reviewed the map and provided suggestions that greatly improved the Qdf1 Qrcc Qt1 final product. ml Qdf2 Qt2 Qal Qrcc

Qal Qt Qal Qt1 Qal SOURCES USED IN MAP COMPILATION Qrcc Qrcc 1 Qdf3 Qt1 ml Qdf Qt2 Bell, Allison M., 1986, Morphology and stratigraphy of terraces in the 2 Qdf4 Qal Qrs Qdf2 upper Shenandoah Valley, Virginia [M.S. Thesis]: West Virginia University, 160 p. Qrcc Qrcc Qt Heller, Matthew J., 2010, Bedrock geologic map of the Elkton West Qt1 2 Qdf4 Qrs quadrangle, Virginia: Virginia Division of Geology and Mineral Resources Open Qdf1 Qdf3 Qt2 File Report 10-04, 1:24,200-scale map. Qal Qal King, Phillip B., 1950, Geology of the Elkton area, U.S. Qt2 Qt2 Qdf2 Qrs Geological Survey Professional Paper 230, 82 p., 1:24,000-scale map. Qdf2 Qdf Qal Qrcc 1 Mason, John E., 1992, Surficial geology of alluvial fans and Qrcc Qrcc Qdf2 Qdf3 terraces on the western flanks of the Blue Ridge Mountains between Elkton and 38° 22’ 30’’ 38° 22’ 30’’ 78° 45’ (MCGAHEYSVILLE) 78° 37’ 30’’ Port Republic, Virginia, [M.S. Thesis]: West Virginia University, 77 p. ) (SWIFT RUN GAP) U.S. Department of Agriculture, 1982, Soil Survey of Rockingham Basemaps, modified U.S. Geological Survey DRG, 1987, SCALE 1:24000 County, U.S. Government Printing Office, Washington D.C., 233 p. MN 1 0.5 0 1 MILE (GROTTOES Elkton West Quadrangle, and DTM created using VGIN GN aerial imagery elevation control points, 2007. 1000 0 1000 2000 3000 4000 5000 6000 7000 FEET

9˚ 34’ 1 0.5 0 1 KILOMETER SUGGESTED REFERENCE 1o 11 ' Digital Cartography by Matthew J. Heller and Amy K. 171 MILS 21 MILS Heller, Matthew J., and Eaton, L. Scott, 2010, Surficial geologic map Gilmer CONTOUR INTERVAL 40 FEET NATIONAL GEODETIC VERTICAL DATUM OF 1929 of the Elkton West quadrangle, Virginia: Virginia Division of Geology and Mineral Resources Open File Report 10-05, 1:24,000-scale map. 2010 MAGNETIC NORTH DECLINATION AT CENTER OF SHEET Geology mapped from May 2004 to December 2009

ANNUAL VARIATION 0˚ 1’