232 N. L. BOW EN 



which it is associated. Adams entered the field as the champion 

 of the newer conception that many banded gneisses are of igneous 

 origin, and that of these the anorthosite was a prominent repre- 

 sentative. Under such circumstances it cannot be questioned that 

 any geologist would search diligently for dikes and tongues of 

 anorthosite running out into the surrounding rocks, and that 

 having found them he would not fail to record them. Yet one will 

 search Adams' report in vain for a single instance of such a dike. 

 The wording of the one statement which is an apparent exception 

 serves only to emphasize the truth of the above. The anorthosite 

 mass is described as "sending an apophysis''' into the surrounding 

 gneiss. 1 The apophysis referred to is a great armlike extension five 

 miles wide. Attention is directed to this lack of dikes in order to 

 emphasize that here we have an intrusive of a peculiar character, 

 not to call in question the interpretation of the anorthosite as an 

 intrusive. Of that there can be no question. Dikes intimately 

 related to the anorthosite do occur, but they serve to emphasize 

 the more that there are none consisting almost entirely of plagio- 

 clase, though there is mile upon mile of such rock within the main 

 body of anorthosite. It seems reasonable to conclude, therefore, 

 from the evidence in the Morin area, that a rock consisting almost 

 entirely of plagioclase is incapable of being injected as dikes. The 

 reason for this is to be found, it is believed, in the manner of its 

 origin, a mass of anorthosite being merely a collected mass of 

 plagioclase crystals. 



There are, as has been stated, several small outlying masses of 

 anorthosite besides the great central mass. These are listed and 

 described in detail by Adams. Some of them were visited by the 

 writer, but nothing need be added, indeed nothing can be added, 

 to Adams' statements, which are quite explicit with reference to 

 the point that it is desired to emphasize. In discussing the anor- 

 thosite of the outlying masses in general he states: "It is perhaps 

 on the whole richer in iron magnesia constituents and often contains 

 minerals such as hornblende and biotite." 2 Statements of like im- 

 port are made in discussing the bands severally. Of the Kildare 



1 Op. cil., p. 116. Italics are the writer's. 2 Ibid., p. 117. 



