Table 3.— Explanation of symbols on maps 



Structure-contour maps 



Structure contour 



10 Altitude of top of unit mapped 



10 Top of unit above this altitude 



10 Top of unit below this altitude 



E Altitudes based on estimated value for land surface 



e Altitude based on estimated thickness 



Datum is mean sea level 



Contour interval is 100 feet for maps of the top of the Oligocene, upper Eocene, and middle 

 Eocene; 200 Feet for top of the lower Eocene, Paleocene, post-Tuscaloosa Cretaceous, 

 and Tuscaloosa Formation; and 500 feet for top of the Lower Cretaceous (?) and pre- 

 Cretaceous; 



Thickness-distribution maps 



Line of equal thickness 



100 Logged thickness 



100 + Plus sign is used to indicate that the figure is a minimum value and that additional 



+ thickness is probable; the location of the plus indicating whether the additional thickness 



is above or below, or as in the case here, with two plus signs, the unit is likely to have 



additional thickness both above and below the 100 feet that were logged as being part of the 



geologic unit 



6 Thickness estimated 



Absent 



Contour interval is 100 feet for all maps except the Lower Cretaceous(?); for it the 

 contour interval is 400 feet. 



Cooperation, Administration, and Acknowledgments 



The availability of material for a report such as this is evidence of the willing and splendid coopera- 

 tion received from the water well drillers of Georgia, and the oil industry, who made the well cuttings 

 available for study and who furnished the drillers logs and the electric logs. 



The work was done under a cooperative program for ground-water investigations conducted by the U.S. 

 Geological Survey and the Georgia Department of Mines, Mining, and Geology, Garland Peyton, Director, 

 and under the supervision of J. T. Callahan, former district geologist, and H. B. Counts, current district 

 engineer, U. S. Geological Survey. 



Paul L. and Esther R. Applin, geologists with the U. S. Geological Survey, have both discussed phases 

 of the work with the authors and the report has benefited from their helpfulness. 



VV. Storrs Cole, Professor of Geology at Cornell University, through his correspondence with the 

 authors, discussed several aspects of the stratigraphy and paleontology thereby making available some 

 of his vast experience on "larger" Foraminifera. 



The illustrations have been drafted by Willis G. Hester. 



