o 



18 PROCEEDINGS OF THE ACADEMY OF [1887. 



divisions of the Kainozoic or Tertiary. It will probably be admit- 

 ted by most geologists that the divisions pre-Glacial (Pleistocene), 

 Glacial, and Recent are merely sub-groups of a single major forma- 

 tion, for which the familiar term Post-Pliocene might be conveniently 

 retained. Its value may be accepted as being approximately equiv- 

 alent to Pliocene, Miocene, Oligocene, or Eocene, although the val- 

 ues of these last differ somewhat among themselves. Indeed, it is 

 not a little difficult to determine what precise significance is to be 

 attached to these divisions of the Tertiary, whether they are of equiv- 

 alent value with the (generally so considered) corresponding terms 

 of the Mesozoic^ -Cretaceous, Jurassic, etc. and Paleozoic series 

 Carboniferous, Devonian, etc or not. In most geological tables they 

 are accorded this value, but it is more than doubtful if they are enti- 

 tled to it. Probably but few geologists will deny that the Post-Pliocene 

 and Pliocene are much more intimately related to one another than 

 are the Devonian and Silurian, the Devonian and Carboniferous, or 

 the Jurassic and Cretaceous. And a similar intimate relation holds 

 by comparison between the Eocene and Oligocene. The Post-Plio- 

 cene and Pliocene, again, appear in most cases to enjoy a much 

 closer affiliation than exists between the latter and the Miocene, and 

 similarly, the bond of union uniting the Eocene with the Oligocene 

 is greater than that which holds the latter to the Miocene. So that 

 Avhile it may be impossible to attach absolute values to the terms or 

 periods marked off in Tertiary chronology, it appears to the present 

 writer more in consonance with existing facts, and as a stricter 

 parallel to the methods employed in pre-Tertiary terminology, to 

 group the entire series into three main sections, corresponding to as 

 many periods of geological time, as follows : 



Neogene f Post-Pliocene. 

 I Pliocene. 



Kainozoic 



or 

 Tertiary 



r 



Metagene Miocene. 



EOGENE I Oligocene. 

 Eocene. 



The classification of the Tertiary deposits, brought en rapport with 

 the classification of the pre-Tertiaiy series, and as based upon the 

 formations of the Atlantic slope of the United States, would then be 

 as follows : 



