|U.S. Geological Survey Open-File Report 98-764
Reconnaissance Bedrock Geologic Map of the Keysville 7.5-Minute Quadrangle, Prince Edward, Charlotte, and Lunenburg Counties, Virginia
By Paul C. Hackley and John D. Peper
The Keysville 7.5-minute quadrangle encompasses approximately 130 square kilometers in south-central Virginia and is primarily underlain by Late Proterozoic metasedimentary, metavolcanic, and associated intrusive rocks. Mesozoic diabase dikes intrude these rocks. The quadrangle is located at the northwestern edge of the Carolina slate belt, an area of volcanogenic greenschist-facies metamorphic rocks in the Piedmont geologic province of the Appalachian orogen. Immediately to the south, in the South Boston 30'x60' quadrangle, the Carolina slate belt is bordered on the east and west by belts of amphibolite-facies gneiss and schist.
The geology of the Keysville quadrangle was mapped as part of the Appomattox 30'x60' quadrangle under the Geology of the Mid-Atlantic Corridor Project of the National Cooperative Geologic Mapping Program. Six weeks of fieldwork in July and August 1997 were spent traversing the quadrangle by four-wheel drive vehicle and on foot. Field notes were recorded at approximately 400 bedrock outcrops and saprolite and soil exposures, and 70 samples were collected for visual inspection and petrographic examination. The map was compiled and text written during August and September 1997. Several key areas in the quadrangle were revisited during July 1998 to revise the locations of geologic contacts.