DEVELOPING 1:24,000-SCALE COUNTY-WIDE GEOLOGIC INFORMATION, AIKEN COUNTY, S.C

Aiken County is located in western central S.C. Its western border with Georgia is the Savannah River, and its northern border lies athwart the Fall Line. The fast-growing city of Augusta, Ga. is across the river, and Aiken County is also undergoing rapid changes. In particular, water availability is becoming an issue. The S.C. Dept. Natural Resources-Geological Survey is working to develop 1:24,000-scale geologic information for Aiken County officials, primarily disseminated in a GIS format. The county is framed by 27 7.5-minute quadrangles. Only 4 quadrangles remain to be mapped, which should be completed by 2009.

Most of Aiken Co. is covered by upper Coastal Plain deposits. Upper Cretaceous through Eocene, marginal marine sequences are exposed adjacent to the Fall Line. Overlying younger deposits consist of braided stream deposits, eolian sands, Carolina bays, and alluvial fill. The metamorphic rocks of the Piedmont make up 2, possibly 3, terranes. The boundary between Savannah River (nee Kiokee) and Augusta terranes is the Augusta fault zone (AFZ). This complex fault has multiple episodes of movement, first ductile, later brittle. AFZ is marked by pronounced silicified quartz breccia. These breccias are currently the focus of mapping to trace their extent and to help decipher the faulting history of the area.

Development of digital maps has greatly improved our ability to compile geologic information. Using GIS, we are able to address edge-matching issues more efficiently, to produce better cartographic products at any scale and with any medium, and to develop and distribute digital map information. In addition to Aiken County, we are in the last stages of completing the following compilations: Mountain Bridge (12 quadrangles); Congaree River Valley (9 quads); Lakes Marion and Moultrie (23 quads); and Savannah to Kiawah Island (24 quads). Many of these are now available, or soon will be, on DNR's GIS Data Clearinghouse: www.dnr.sc.gov/gis.