Everona Limestone (Jonas, 1927). Thinly-laminated medium-bluish-gray limestone with graded, graphitic silty partings; includes calcareous graphitic phyllite, and pyrite-bearing graphitic slate. Mineralogy: calcite + quartz + muscovite ± graphite ± chlorite ± albite ± pyrite + tourmaline. The Everona occurs dominantly as lenticular bodies immediately north west of or within the Mountain Run fault zone (Evans, 1984; Conley, 1989; Rossman, 1991). In most outcrops primary laminations are complexly folded due to strain accommodation associated with the Mountain Run fault. Unit thickness and degree of lateral continuity are structurally controlled in many places. Mack (1965) reports thicknesses ranging from about 20 to 1100 feet. Jonas (1927) reports retrieving trilobite fragments from sandy beds adjacent to the Everona, but these were so poorly preserved that E.O. Ulrich could not identify them, even with respect to genus. Recent attempts to extract conodonts from the Everona have so far proven fruitless. The Everona is interpreted to be in stratigraphic continuity with phyllites and metasiltstones that are conformable above the Catoctin Formation (Evans, 1984; Rossman, 1991), and is likely Early Paleozoic in age.
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.