Dominantly leucocratic to mesocratic, medium- to coarse-grained, strongly-lineated granite gneiss; includes porphyritic granite gneiss. Mineralogy: quartz + potassium feldspar + plagioclase + biotite + muscovite ± garnet. Geophysical signature: western portion coincides with strong positive radiometric anomaly. This unit likely includes more than one intrusive body; portions may be derivative of felsic volcanogenic rocks. These rocks intrude and are interlayered with metavolcanic rocks of probable Cambrian age. The unit includes granite gneiss of Nelson (1992), and may be correlative in part with the Shelton Formation (Ost).
Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia: Virginia Division of Mineral Resources, scale 1:500,000.
Virginia Division of Mineral Resources, 2003, Digital Representation of the 1993 Geologic Map of Virginia, Publication 174, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, scale 1:500,000.