GEOLOGIC MAP OF THE GRIFFIN, GEORGIA 1-DEGREE X 30-MINUTES, 1:100,000-SCALE QUADRANGLE

The Griffin Quadrangle spans from the Dog River window, in it’s northeastern corner, across the Brevard fault zone, inner Piedmont, and Towaliga fault zone, to the Pine Mountain window along it’s southern edge. One northwest-trending set of diabase dikes cross the quadrangle. A single dike occurs southwest of the main diabase dike swarm and another southeast of Athens, GA. Two swarms of mafic dikes appear to be related to the diabase dikes, upon which they concentrate. The quadrangle was mapped in detailed reconnaissance geologic mapping in the mid-1970’s by Higgins and Atkins. Since then Atkins and Grant conducted detailed geologic mapping of the Carboniferous Cedar Rock Granite, distinguishing several varieties of granite within the Cedar Rock. Additional structural details were added by Higgins and Crawford in the 1980’s through 2009. The geologic map was digitized by Higgins and Crawford in 2009. Screens, generally about half granite and half country rock extend from many of the granites in the quadrangle. The screen from the Palmetto Granite extends eastward for more than 25 km before it turns northeastward into the adjacent 1:100,000-scale Atlanta Quadrangle, where it was not mapped. It can be seen on recent compilations of aeromagnetic maps by D.L. Daniels (USGS). We thank the U.S. Geological Survey and the Georgia Geological Survey for their support of this project.