136 



AZOIC AGE. 



up to view in the same process. Moreover, the Azoic, if it had not 

 undergone flexures before the Silurian beds were laid down, would 

 partake of the Silurian flexures, or, in other words, be conformable 

 to the Silurian strata. But if it had been flexed or tilted in some 

 previous period of disturbance, then the Azoic would be unconform- 

 able to the Silurian, although both were finally upthrown together 

 in the making of the mountains. 



In the study of Azoic regions these points require special investi- 

 gation. 



The Azoic areas of North America of the first kind (and partially, 

 it may be, of the second) are shown, as far as now ascertained, on the 

 accompanying map of the Azoic continent. The Azoic lands on this 



Fig. 139. 



Azoic Map of North America. 



chart are represented as the dry land of the era, while the rest of 

 the continent is submerged. They are concluded to have been thus 

 dry, because no marine beds cover them, while, on either border, 

 marine beds (Silurian and later) commence and spread widely over 

 the most of the continent. The outline of the continent and of the 



