[bailey] volcanic rocks OF NEW BRUNSWICK 137 



ory'stalline rock, consisting mainly of an admixture of augite and 

 plagioclasc, with some magnetite and occasionally native copper, and 

 in part of a more earthy granular material, variously coloured, which 

 is more or less amygdaloidal, and in places carrying zeolitic minerals, 

 such as Thompsonite. In all respects these rocks show the closest resem- 

 blance to those of the North Mountains of Nova Scotia, and are, no 

 doubt, connected with the latter by submerged ridges lying along the 

 bottom of the Bay of Fundy trough. There is nothing at Grand Manan 

 to indicate their age, except that they overlie, as in the Annapolis valley, 

 Triassic red sandstones, but probably, as is certainly the case in the 

 valley last named, their ejection was not wholly subsequent to the 

 Eed sandstone era. 



Summary. 



Summing up the foregoing observations we may note: 



(1) That the great periods of volcanic activity in the history of 

 New Brunswick were four in number, viz. : the Huronian, the Silurian, 

 the Lower Carboniferous and the Trias. 



(2) That the volcanic rocks of the Huronian, so far as known, 

 are confined to the southern counties, not occurring at distances of 

 more than thirty miles from the modern coast. The Silurian volcanics 

 on the other hand cover large areas in northern and central, as well as 

 in southern New Brunswick, being the most widely distributed of all 

 the formations represented. 



(3) That the Lower Carboniferous volcanic rocks are confined to 

 areas, such as the great central basin and the Bay of Fundy trough, 

 which had been produced by the great series of plications or earth- 

 movements which marked the close of the Devonian age. 



(4) That no volcanic disturbance affected the mainland of New 

 Brunswick subsequent to the close of the Lawer Carboniferous, the 

 later ejections of the Jura-Trias being confined to the still subsiding 

 trough of the Bay of Fundy. 



(5) That the most abundant and typical volcanic rocks of the 

 Pre-Cambrian (Huronian) system are diorites and diabases, those of the 

 Silurian felsitic and porphyritic rhy elites, those of the Lower Car- 

 boniferous dolerites, and those of the Tiria.s, basalts or augite-plagio- 

 clases. With the three former are associated felsites, porphyrie? .ind 

 breccias, variously coloured, which are wanting with the last. Amygda- 

 loids occur with all, but zeolites are rare in the more ancient volcanics. 

 The earliest igneous rocks (Huronian) are about equally divided between 

 the basic and acidic types; the latter predominate in the Silurian, 

 and the former in the Trias. 



