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CHAPTER XXI. 



THE DEVONIAN PERIOD. 



LOWER DEVONIAN OF NOVA SCOTIA. DEVONIAN OF SOUTHERN Nl.W 



BRUNSWICK. SECTION OF " FERN LEDGES." USEFUL MINERALS. 



CRUSTACEANS AND INSECTS. 



The growth of geological knowledge in Nova Scotia and New Bruns- 

 wick is in nothing more marked than in the fact that, in 1855, two 

 chapters of Acadian Geology, and those somewhat meagre, sufficed 

 for all the rocks older than the Carboniferous, while now the quantity 

 of matter on these rocks will be more than doubled, and it will be 

 necessary to subdivide them into several series. 



In the present chapter I propose to describe the group of rocks imme- 

 diately under the Carboniferous system, that to which the name Devo- 

 nian has been given by the English geologists, and which is represented 

 in the United States by the formations from the Catskill or Old Red Sand- 

 stone to the Oriskany Sandstone inclusive. I may remark that the con- 

 troversy which has been raised by Mr Jukes, as to the use of the term 

 Devonian in England, in no respect affects the questions we have to 

 discuss, since whatever views may be entertained l-especting the rocks 

 known as Devonian in Devonshire and in Ireland, in America the 

 existence of a great mass of sediment, characterized by a distinct fauna 

 and flora, between the Carboniferous and Upper Silurian, is a fact 

 which cannot be set aside. It is also to be observed that in the 

 Acadian Provinces, in passing downward from the Carboniferous to 

 the Devonian we constantly find unconformability, and that there is 

 ample evidence that the great masses and dikes of intrusive granite 

 which in Nova Scotia penetrate all the rocks older than the Carbon- 

 iferous belong to the close of the Devonian period. 



I had to remark in regard to the Carboniferous period that a well- 

 narked difference in the deposits could be observed in the regions 

 east and west of the Alleghany mountains. A similar difference 

 exists in the Devonian. Beds of oceanic character are much less 

 developed in the Acadian region than they are in New York and 



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