﻿140 0. D. Walcott — Cambrian System of North America. 



tion of that bulletin. In establishing the stratigraphic position 

 and paleontologic characters of the Georgia or Olenellus fauna 

 of the Middle Cambrian, the key to the succession of the Cam- 

 brian faunas was obtained, and the sections that are correlated 



Table showing the correlations of typical Cambrian Sections with 

 reference to the Potsdam and Georgia faunas of the Cambrian. 



OBDOVTCIAN or 



LOWER SILURIAN. 



Upper Limit of 

 Upper Cambrian or Potsdam horizon. 



UPPER CAMBRIAN 



== POTSDAM OR 

 DICELLOCEPHALUS. 



MIDDLE CAMBRIAN 



Central horizon of Middle Cambrian 



A 



.= GEORGIA OR OLENELLUS. 



LOWER CAMBRIAN 



= ST. JOHN SERIES. 



NEWFOUNDLAND AND 



BRAINTREE, MASS., OR 



PARADOXIDES. 



Base of Cambrian. 



Km 



ci 



§ 



SI 



<; 



>o o 



!4 



PRE -CAMBRIAN and. ARCHEAN. 



in the diagram (fig. 1) are placed on the general section with 

 relation to the stratigraphic position of Olenellus and Dicello- 

 cephalug, or Georgia and Potsdam faunas. 



