AMERICAN JOURNAL OF SCIENCE 



[FIFTH SERIES.] 



Aet. I. — Genetic Features of Alnoitic Rocks at Isle 

 Cadieux, Quebec; by N. L. Bowen. With Plate I. 



Introduction. 



In the vicinity of Montreal, Canada, several intrusive 

 masses of alnoitic character have been found that are 

 genetically related to the main Mount Royal intrusion. 

 It was, indeed, from this area that Dr.- F. D. Adams 

 described the first alnoite found on this continent, 1 These 

 alnoites have a remarkable tendency to form breccias with 

 the invaded pre-Cambrian and Paleozoic rocks and an 

 excellent description of them, with particular reference 

 to the breccia, has been given by Dr. Robert Harvie. 2 



During the past summer my attention was called by Dr. 

 Harvie to the fact that a new occurrence had been found 

 at Isle Cadieux in the course of a road-materials survey, 3 

 but that no detailed work had been done on it. Accord- 

 ingly the locality was visited and the material collected 

 has been found to be of such interest as to warrant special 

 description. I am greatly indebted to Dr. Harvie and to 

 the Director of the Geological Survey of Canada for the 

 opportunity of making this study. 



Location. 



Isle Cadieux is a flag station at mileage 26.8 from 

 Montreal on the Canadian Pacific short line between 

 Ottawa and Montreal. The outcrop of alnoitic rocks is 



'P. D. Adams, this Journal, (3) 43, 269-279, 1892. 



2 On the origin and relations of the Palaeozoic breccia of the vicinity of 

 Montreal, Trans. Koy. Soc. Can., 3d Ser., vol. 3, sec. IV, pp. 249-299, 1910. 



3 Geol. Surv. Can., Summary Keport for 1916, pp. 198-206. 



Am. Jour. Sci.— Fifth Series, Vol. Ill, No. 13.— January, 1922. 



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