PRELIMINARY GEOLOGIC MAP OF NINETY SIX NATIONAL HISTORIC SITE AND VICINITY, NINETY SIX 7.5 MINUTE QUADRANGLE, SOUTH CAROLINA

This is the second report of an on-going project to develop a detailed digital geologic map of Ninety Six National Historic Site (NSNHS) and vicinity for National Park Service and the USGS Geologic Resources Inventory. The first report provided a digital surficial geologic map of the area within the boundaries of NSNHS (White and others, 2012). The NSNHS resides in the southeastern part of the Ninety Six 7.5 Minute Quadrangle, South Carolina. The purpose of this report is to provide a digital bedrock geologic map of the southern half of the Ninety Six 7.5 Minute quadrangle. The quadrangle is part of the Charlotte terrane, generally interpreted as the plutonic axis of the Carolina terrane, remnants of a Neoproterozoic to Early Paleozoic exotic volcanic island arc accreted to southeastern North America during Paleozoic tectonic events that formed Pangaea. The surface topography of the quadrangle consists of gently rolling hills with a hundred feet or so of relief. The bedrock is deeply weathered and overlain in most places by a thick layer of soil. Exposures are found mainly in streams and deep road cuts. Unfoliated, tan to light gray, fine to medium grained biotite metagranite is the predominant rock type. The metagranite is cut in numerous places by small plugs and dikes of unfoliated, medium to dark gray, fine to medium grained hornblende metadiorite containing varying amounts of biotite and pyrite. Cross-cutting relationships suggest the metadiorite is younger than the metagranite. The metagranite and metadiorite generally display a xenomorphic-equigranular texture, which suggests they are metamorphic rocks. Metagabbro crops out in various places in the southernmost part of the quadrangle. Fine grained quartz-muscovite schist, variably tan to hematite red, crops out on high ridges within the city of Ninety Six and in the northeasternmost part of the quadrangle.