go Bulletin 15 400 



Oligocene species, or their varieties, are in the Vicksburg and 

 Chipola beds, and as more of the Chipola species are described 

 further similarities may be noted. This incomplete evidence, 

 furnished by the invertebrates, is strengthened by the resem- 

 blances found by Scott and others between the vertebrate faunas 

 of the two continents during the period. 



The stratigraphic indications are also not decisive. The 

 Paris basin Kocene (calcaire grossier) is represented by the Clai- 

 borne, and the European Miocene by the Chesapeake Miocene. 

 Between both these equivalents are beds chara(5terized by inter- 

 mediate faunas. If the Vicksburg and Chipola beds were cut off 

 from the Eocene and Miocene by stratigraphic breaks we should 

 have to recognize them as corresponding to the Oligocene. But 

 a far stronger unconformity exists between the Vicksburg and 

 the Chattahoochee series than has yet been observed between the 

 Vicksburg and the Eocene, or between the Alum Bluff beds and 

 the Miocene. This would seem to indicate that the Vicksburg is 

 really upper Eocene and the Chattahoochee lower Miocene, were 

 it not for the very marked faunal difference, induced by change 

 in elevation, between the Chipola beds and those of the Chesa- 

 peake Miocene. Although it is at present impossible to refer the 

 Vicksburg and Chipola epochs to the Oligocene of Europe with 

 absolute certainty, yet the balance of probability points in that 

 diredlion. 



Correlation tabic. A correlation table of the European and 

 American beds which have been discussed in the preceding pages 

 is appended. 



The nomenclature of the Oligocene epochs in Europa is very 

 variable. The system followed by the writer has been to use the 

 term and its extension given in the region in which the deposits 

 are most typical. Thus the Tongrian is substantially that of 

 Dumont, the Rupelian that of Dumont as modified by Mourlon 

 and later Belgian geologists, the Stampian that of Cossmann and 

 Eambert, and the Aquitanian that of Mayer. 



