68 



of glacial wear and those found around volcanic vents, where particles of 

 rock have been torn from the walls and blown out upon the surface of 

 the earth. These if dropped into the sea would soon be covered up by 

 fine mud and preserved in their original crystalline condition. The Etche- 

 minian appears to represent largely the submarine condition of such effusive 

 rocks. On the other hand, the Coldbrook series, as has been intimated above, 

 represents the preceding sub-aerial phase of the eruptives. It is true that 

 we find in many places conglomerates at the contact of these two series 

 . of rocks, thus diverse in appearance ; but elsewhere there are no beds of 

 rolled fragments at the contact, and the passage is direct from ash-beds 

 or diabases, to the slates and sandstones. In reports of the Canadian 

 Geological Survey of 1870-71, pp. 57-59, etc., relating to the province of 

 New Brunswick, both these groups of rocks have been included in the 

 Huronian system. They may be equivalent in age to the upper part of 

 that series, but unfortunately the absence of fossils in the original 

 Huronian leaves this matter in doubt. 



Pre-Cambrian As we contemplate the physical conditions of the initial epochs of 



Maritime Cambrian time in the Maritime Provinces, we seem to see a region long 



Provinces elevated above the sea, now subjected to depression nearly to the sea 



level, the depression being accompanied with extrusion of lavas and 



volcanic mud and the ejection of stones and ashes. These at first were 



cast upon a land surface, but, as the crust of the earth continued to sink, 



it was covered by the sounds and bays of a shallow sea, diversified with 



pre-Cambrian ridges and islands, of greater or less extent. 



For the above reasons, as well as because the stratified rocks of the 

 underlying complex are markedly unconformable to the Cambrian, the 

 volcanics are thought to belong to the latter, and to give the natural base 

 of this system. 



The accompanying table will then show the classification of the Cam- 

 brian system, as seen in the Maritime Provinces of Canada. 



(See accompanying sheet.) 



