CHAPTER XXV 



THE DEVONIAN PERIOD 



The name Devonian, taken from the English county Devonshire, 

 was proposed by Sedgwick and Murchison in 1839 ; it has found 

 universal acceptance and has passed into the geological literature 

 of all languages. 



As in the Ordovician and Silurian, and for the same reason, the 

 divisions of the New York Devonian are taken as the standard of 

 reference for North America. 



Devonian 

 System. 



Upper 4. 



Chemung 



C: 



Chemung Stage. 



Devonian. 



Series. 



Portage Stage. 



Middle 3. 



Hamilton 



i;: 



Hamilton Stage. 



Devonian. 



Series. 



Marcellus Stage. 



f 2 * 



Corniferous 



V, 



Corniferous Stage 



Lower 



Series. 



Schoharie Stage. 



■ Devonian. 1 1. 



Oriskany 







Series. 







Distribution of the Devonian 



V 



American. — In North America the passage from the Silurian 

 to the Devonian is very gradual, the former drawing to its close 

 without disturbance ; and there is still some difference of view as 

 to just where the line between the two systems should be drawn. 

 Many European geologists are of the opinion that the Lower 

 Helderberg should be included in the Devonian, but in this 

 country it is generally referred to the Silurian. 



At the opening of Devonian times the shore line of North 

 America was approximately as follows. Beginning on the coast of 

 the Arctic Ocean, not far from the mouth of the Mackenzie, it 

 follows a general southeasterly course to the region of Lake 



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