DIGITAL GEOLOGIC MAPS (1:24,000 TALLASSEE, CARRVILLE, NOTASULGA AND LOACHAPOKA QUADRANGLES) ALONG THE PIEDMONT-COASTAL PLAIN ONLAP OF ALABAMA AND THEIR TECTONIC IMPLICATIONS

We present the first geologic map of the 1:24,000 Tallassee, Alabama Quadrangle, which lies along the “fall line” where southernmost Appalachian metamorphic rocks are onlapped by Gulf Coastal Plain Sediments. Our map combines with three recently completed quadrangle maps, from west to east, the Carrville, the Notasulga, and the Loachapoka quads, to provide better constraints on the lithologies and structures of the southernmost exposures of the Appalachian eastern Blue Ridge, Inner Piedmont, and Pine Mountain terranes. Basic research results help to clarify several unusual features associated with the Brevard zone before it becomes buried beneath the Coastal Plain to the south. Results also aid in showing how eastern Blue Ridge rocks have been incorrectly assigned to the Inner Piedmont and that the Stonewall line appears equivalent to the “early-stage” Brevard zone. On the applied side, this area lies along the rapidly developing I-85 corridor, where our geologic maps aid planners, developers, and workers at various State and local agencies mandated to monitor and manage environmental issues.

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 using an IDEAL® FSC 8010, 85 cm wide, color scanner at Auburn University. The scanned images were imported into a standard PC using Corel Designer 9.0® software. The topographic base map was digitally overlaid and geological information was digitized using a Wacom® touchscreen monitor and pen. The digitized map and various layers 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 5000 plotter in the Department of Geology and Geography, Auburn University.