250 A. F. Foerste — Chipola Miocene of 



the cold water current may never have been strong enough 

 to totally exclude the warm water fauna so far westward, and 

 hence an intermixture of Chipola and Chesapeake faunas with 

 a decrease of the cold water elements must be expected on 

 going westward beyond the sphere of strongest influence of this 

 current. Finally, the phytogene phases being of course a fixed 

 horizon only relatively, showing only a general concordance of 

 continental development southward, it may be, that while the 

 Alum Bluff region was receiving phytogene perezonal deposits, 

 the invading Chesapeake fauna of this time, although excluded 

 from the Alum Bluff area, passed by to the southward, and 

 reached western areas before certain localities in this western 

 region had assumed the phytogene phase. This would be 

 quite naturally the case if the elevation of the Chipola land 

 was more pronounced eastward in the Appalachicola area, than 

 westward in the Yellow River region. The result would be 

 the introduction of a Chesapeake element into the Chipola 

 fauna at a time preceding the phytogene stage of these west- 

 ern regions. In this manner a certain commingling of Chesa- 

 peake and Chipola types might be expected to exist both in 

 the formations preceding and in those following the phytogene 

 phase westward. With a full understanding of all of these 

 possibilities it may be possible to establish in the future on the 

 basis of detailed work, some such correlation between the 

 Miocene horizons of the Appalachicola embayment and the 

 various members of the Grand Gulf group, as that suggested 

 in the preceding lines, on the results of the present stage of 

 knowledge, and in consequence partly of the discovery of the 

 phytogene character of the upper Chipola sands at Alum Bluff. 

 It is hoped these observations may encourage further investi- 

 gation and not be considered final. 



The Chesapeake formation at Alum Bluff merges at the top 

 into a few feet of a dark looking clay, the burrowing places of 

 thousands of mud-burrowing bees, in which clay occur Chesa- 

 peake fossils, in some places rather plentifully. While of 

 course it would be useless to deny the total absence of phyto- 

 gene remains here, since negative evidence is never final, it 

 should be said that the writer made two trips to this region, 

 one for the special purpose of determining this question, and 

 while there was no trouble in tracing the loose palmetto leaf 

 and other remains to the Upper Chipola sands and their inter- 

 laminated clays in the cliffs above, where they occur in situ, 

 in no instance was any leaf or stem found by us in the peculiar 

 dark clays which terminate the Chesapeake at this locality. 



