178 S. W. McCALLIE 



EOCENE SERIES 



The Midway formation, which forms the base of the Eocene 

 series, lies unconformably upon the upper member of the Cretaceous 

 and is unconformably overlain by the Wilcox. It consists of sand, 

 clay, and marl, and forms a narrow northeast-southwest belt 

 extending from Fort Gaines on Chattahoochee River to a point a 

 short distance east of Flint River in Houston County. At no 

 place does it exceed twelve miles in width. 



The Wilcox formation has a distribution similar to the Midway, 

 though it probably does not extend beyond Flint River. It is 

 made up mainly of sandy, glauconitic shell marl and laminated, 

 sandy, dark-colored lignitic clay. Near Flint River pure beds of 

 white clay occur, with red and varicolored sand. 



The McBean formation forms an extremely irregular belt which 

 varies from two to thirty miles or more in width and extends entirely 

 across the state. East of Ocmulgee River it rests unconformably 

 on the strata of Lower Cretaceous age, while between Flint and 

 Chattahoochee rivers it rests unconformably upon the Wilcox 

 formation. It consists of shell marl, sandy limestone, glauconitic, 

 calcareous sands, and clays in the form of fuller's earth. 



The Ocala limestone, which is best developed between Ocmulgee 

 and Chattahoochee rivers, is the main representative of the Jackson 

 group in Georgia. Its eastern boundary lies usually a few miles 

 west of Flint River, whence it extends south and west as a broad 

 belt to the Georgia-Alabama-Florida state line, with an average 

 width of more than thirty-five miles. The formation, as the 

 name suggests, is made up of limestone with more or less chert in 

 places. 



OLIGOCENE SERIES 



The Oligocene series is represented by the Vicksburg, the Chatta- 

 hoochee, and the Alum Bluff formations, subdivisions of the 

 Appalachicola group. The three formations are confined largely 

 to the southern part of the Coastal Plain near the Georgia-Florida 

 state line and to irregular areas southeast and southwest of Macon. 

 The Vicksburg and the Chattahoochee formations, which are 

 separated by an unconformity, consist largely of limestone, while 

 the Alum Bluff formation is made up mainly of sands and clays. 



