WARLICK, Cameron, Camerow@clemson.edu and CASTLE, James, jcastle@clemson.edu, 340 Brackett Hall, Geological Sciences, Clemson University, Clemson, SC 29634; and CLENDENIN, C.W., S.C. Geological Survey, Columbia, SC.

The purpose of this study is to provide geologic map information for assessing groundwater availability for a major residential development on Glassy Mountain, South Carolina Piedmont.  The area mapped lies within the Saluda North 7.5-minute quadrangle, located north of Greenville, South Carolina.  Rock types in the area are quartz-biotite-feldspar gneiss, minor biotite-hornblende schist, and minor amphibolite. A number of faults and fractures are present throughout the study area.  A basin atop Glassy Mountain is bisected by the Hogback Mountain Fault, which is a northeast-southwest striking oblique-slip fault.  Laterally extensive, near-horizontal sheet fractures and low-angle thrust faults are also present.  Relations between the structural styles suggest polyphase deformation.
     Mapping shows that groundwater flow is structurally controlled.  Springs and seeps occur along near-vertical faults and fractures.  Substantial flow has been observed from fractures using borehole camera footage in a well used for water supply.  Within the map area, existing wells with the greatest production rates are located in a zone of vertical fractures adjacent to the Hogback Mountain Fault.  A new well confirms the importance of structural control on groundwater flow.  This well, drilled adjacent to an area of sheet fractures and vertical fractures, has a tested production rate of 150 gallons per minute.