379 The Oligocene of the Southern United States 69 



evidences are, the presence, at the base of the Chattahoochee, 

 of a conglomerate, usually formed of rolled limestone pebbles not 

 distinguishable lithologically from the Vicksburg; the irregular 

 surface between the Vicksburg and Chattahoochee series, and the 

 presence of masses of chalcedonized corals between the series, 

 which indicates a period of submergence. 



Chattahoochee , Chipola and Ahim Bluff beds. The red clay 

 hills of the plateau region of southeastern Georgia have 

 been shown by Dr. Pumpelly* to be formed of Chattahoochee at 

 the base, overlaid by Chipola, which is, in turn, followed by Alum 

 Bluff sands. These are doubtless continuations of the Florida 

 beds. 



Altaviaha grits. On the Ocniulgee River are beds which 

 correspond lithologically and faunally with the Hawthorne beds 

 of central Florida. These beds were first described by R. H. 

 IvOUghridgef as resembling the Grand Gulf sandstone. Dr. Dallj 

 later named them the 'Altamaha grits.' The grits are developed 

 in Irwin, Dodge, Ware, Tatnall and other counties. The grits 

 represent a perizonal deposit formed under the same conditions as 

 the Grand Gulf sandstones, and are, chronologically, nearly 

 equivalent to the Hawthorne beds of Florida. 



Alabama. 



The White limestone. The Vicksburg limestone in Alabama, 

 as in Georgia, is underlaid by Jackson, from which it can be dis- 

 tinguished only by the fauna. The two together form the White 

 limestone that Tuomey|| described, in 1850, from exposures on the 

 Alabama River. This is identical with the White limestone of 

 St. Stephens on the Tombigbee. The latter was referred to in 

 1846 by Conrad§ as probably of the same age as the Vicksburg. 



* Ibid., pp. 445-6. 



■\ loth Census, vol.6, pt. 2, pp. 15-6. 



XBull. U. S. Geol. Survey, No. 84, p. 81. 



\ First Biennial Rep., Geol. of Ala., 1850, p. 152. 



\Ainer. Jour. Sci., 2nd ser., vol. 41, 1S66, p. 96. 



