164 DALL AND STANLEY-BROWN — APALACHICOLA RIVER GEOLOGY. 



oughly silicified, usually of a pale yellow color, but in the more siliceous 

 portions white or gray or, when partially oxidized, varying in shades of 

 ferruginous brown. The remnants left by solutionary processes are 

 almost always reddened by oxidation. The beds which in other parts 

 of Georgia and Florida may be correlated with the Chattahoochee series 

 are as follows : The Hawthorne beds of central Florida and the thin layer 

 containing oysters and corals which Burns found intercalated between 

 the Vicksburg limestone and the Altarnaha grits on the Ocmulgee river 

 in Georgia, the Orthaulax bed and Tampa limestone of Tampa, Florida, 

 and the chert of Hillsborough river. Heilprin's Cerithium rock also 

 belongs here, and Bailey's " infusorial earth " of Tampa. The fauna 

 which characterizes them is also found represented mechanically mixed 

 with later forms in the marls of Shiloh, New Jersey. 



This fauna is very closely allied to that of the Chipola beds and has 

 not been completely worked out, but is intimately connected with the 

 Miocene of the West Indies, Jamaica, Trinidad, Haiti, Curagao, Panama 

 and Costa Rica. Many of the species are the same as those of the Chipola 

 fauna, but others are peculiar, sufficiently so to warrant the separation 

 of the Chattahoochee from the Chipola as a distinct series. The forms 

 which characterize the former alone, as far as our present knowledge 

 goes, include Orthaulax pugnax, several species of Pyrazislnus, Oerithiiim 

 hillsboroensis, Potamides transecta, Natica amphora, Oyrena vesica and Orbito- 

 lltes floridanus. The last has been repeatedly mentioned as found in 

 rocks of the Chipola series, and there is no particular reason why it 

 should not occur there, since there is a recent species of OrbitoUtes not 

 to be distinguished from OrbitoUtes floridanus, which has been dredged in 

 large quantities on the Gulf coast by the United States Fish Commis- 

 sion. Nevertheless, the fact remains that so far I have been unable to 

 detect any trace of this fossil in any of the typical Chipola beds, and 

 believe that the report of its presence there is due to some misidentifica- 

 tion. Certain corals and a peculiar oyster are very characteristic of* the 

 lower zones of the Chattahoochee everywhere, but have not yet been suf- 

 ficiently studied to be precisely identified, and may also occur at higher 

 levels. The same may be said of several echini. Since the Altamaha 

 grits are of analogous and probably synchronous origin with the much- 

 debated Grand Gulf beds, it is probable, from Burns' observations, that 

 the latter are in large part synchronous* with the Chattahoochee series; 

 and the erosion by which the Grand Gulf sediments were formed may 

 have started with the movement in elevation which finally raised these 

 older Miocene beds in Costa Rica to a very considerable height above 

 the sea. 



*See Bull. 84, U. S. Geol. Survey, pp. 82, 8.3, 1892. Professor E. A. Smith, State Geologist of Ala- 

 bama, from unpublished data had come to the conclusion as early as September, 1892, that the 

 typical Grand Bluff beds should be correlated with the older Miocene of the Apaiachicola section. 



