DIGITAL GEOLOGIC MAP OF THE 1:24,000 BEULAH, ALABAMA, QUADRANGLE: MINERAL RESOURCES AND TECTONIC DEVELOPMENT SPANNING WIDTH OF THE PINE MOUNTAIN WINDOW

We present the first geologic map of 1:24,000 Beulah, Alabama Quadrangle. The quadrangle lies just 10 km north of the “fall line” where southernmost Appalachian metamorphic rocks are onlapped by Gulf Coastal Plain Sediments. The Beulah quad spans the entire breadth of the Pine Mountain window, hence our results provide better constraints on the lithologic and structural evolution of the southern Appalachians' most internal Grenville basement window that preserves its primary miogeoclinal cover. We have discovered a tremendous, 6 km thick sequence of Halawaka rift metasedimentary rock that extends the Laurentian rift basins (Ocoee basins) much farther southward than was previously known. Detailed lithologic information documents successive shallowing (quartz sandstone deposits) and deepening (arkose) of the basins during extension. The late- or post-Appalachian Towaliga normal fault later brought far-traveled Inner Piedmont and eastern Blue Ridge allochthons of the hanging wall down upon these rift deposits of the Pine Mountain window footwall.

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 federal, state, and local agencies mandated to monitor and manage the environment. Quartzite and granite bodies hold potential for aggregate stone resources.

The computer generated map was 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 overlayed 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.