HISTORICAL GEOLOGY. 141 



IV. Cenozoic Time. 



1. The Tertiary, or Age of Mammals. 



2. The Quaternary, or Age of Man. 



Subdivisions into Periods and Epochs. — The subdivisions under the 

 ao-es. the periods and epochs, vary, as has been said, in different coun- 

 tries. The following table (Fig. 201) presents a general view of those 

 of eastern North America, so far as the Paleozoic is concerned, — the 

 Silurian, Devonian, and Carboniferous being well represented on the 

 North American continent. The rest of the series is from European 

 geology, in which the later ages are far better represented than in 

 America. In this Manual, American geology is in general first con- 

 sidered; and afterward such further illustrations are drawn from other 

 continents as are necessary for comprehensive views and generaliza- 

 tions. Where America is deficient in its records, the European are 

 taken as the standard. 



The names of the periods and epochs for the Paleozoic of America 

 are, in the main, the same that have been applied to the rocks by the 

 New York geologists. 



