DIGITAL GEOLOGIC ED-MAPS OF THE 1:24,000 LOACHAPOKA AND NOTASULGA QUADRANGLES, EAST-CENTRAL ALABAMA, PIEDMONT & GULF COASTAL PLAIN

We present digital geologic maps of the 1:24,000 Loachapoka and Notasulga Quadrangles, east-central Alabama. The area underlying the quadrangles straddles the boundary between the Appalachian Piedmont (Inner Piedmont and Pine Mountain terranes) and Gulf Coastal Plain (Tuscaloosa Group) physiographic provinces. The Geological Survey of Alabama and its Geologic Mapping Advisory Committee has placed a high geologic mapping priority for this area mainly for socio-economic reasons. Interstate I-85, the primary route between Atlanta, Georgia, and Montgomery, Alabama, passes through the southern parts of the quads. The towns of Loachapoka and Notasulga lie on the western outskirts of Auburn, one of the most rapid growing cities in the state. Detailed geologic mapping is needed for planning and development and for future wellhead protection studies as required by the Alabama Department of Environmental Management. Mapping also helps to delineate high-silica quartzite and granite bodies that, due to the area’s occurrence along the fall line, are the most southern sources of crystalline rock available for aggregate stone for a large part of the southeastern U.S. The local population also is concerned about the possible environmental impact of a proposed granite quarry on Saugahatchee Creek, a major recreational feature that passes through the northern parts of the quadrangles. Basic research goals include gaining a better understanding of how the Laurentian margin evolved and subsequently was dismembered and reassembled during the Appalachian orogeny, which has broader implications for the growth of continents, Laurentian-Gondwanan plate interactions, and supercontinent cycles. The computer generated maps were developed by scanning the topographic quads and hand-drawn overlays of station localities, structural/fabric data, contacts, and structural traces as a jpeg file using an IDEAL® FSC 8010, 85 cm wide, color scanner at Auburn University. The scanned image was imported into Corel Designer 9.0® software and digitized using a standard PC and a Wacom® pad and pen. The digitized map and various layers then were printed directly from Corel Designer 9.0® or exported as a Windows® metafile (wmf) into other drawing software packages and printed on an HP Designjet CP 5000 plotter in the Department of Geology and Geography, Auburn University.