METHODS — GEOLOGICAL 



17 



different classification. The South American formations are 

 given in a separate table, as it is desirable to avoid the appear- 

 ance of an exactitude in correlation which cannot yet be at- 

 tained. 



Quaternary period 



Tertiary period 



CENOZOIC ERA 



Recent epoch 



Pleistocene epoch = Glacial and Inter- 

 glacial stages. 

 Pliocene epoch 

 Miocene epoch 

 OUgocene epoch 

 Eocene epoch 

 Paleocene epoch 



Continuing the subdivision of the Tertiary period still 

 farther, we have the following arrangement : 



TERTIARY PERIOD (North America) 



Pliocene 



Miocene 



OUgocene 



Eocene 



Paleocene 



Upper 

 Middle 



Lower 



Upper 



Middle 



Lower 



Upper 



Lower 



Upper 



Middle 



Lower 



Upper 

 Lower 



Wanting 

 Blanco age 

 Thousand Creek age 

 Snake Creek age 

 Republican River age 

 Loup Fork age 

 Deep River age 

 Arikaree age 

 John Day age 

 White River age 

 Uinta age 

 Bridger age 

 Wind River age 

 Wasatch age 

 Torre j on age 

 Puerco age 



Fort Union 



