[HOWARD] SOME OUTLIERS OF THE MONTEREGIAN HILLS 



89 



almost opaque even in thin section by the hydrous iron ore. The 

 only minerals which could be identified are calcite, quartz, and an 

 indefinite feldspathic mineral. This dyke is of no importance except 

 that it is undoubtedly associated with the breccias which lie about 

 one-half mile to the east. 



These breccias do not appear to be genetically connected with 

 the fourchite sill. The only evidence in favour of this connection 

 consists of the proximity of these breccias to the sheet. 



On the other hand, this fourchite is not in any way similar 

 to any of the other exposures described in this paper, and the 

 breccias at La Trappe as well as all those described by Harvie are 

 closely related to alnoitic rocks- The biotite present in the paste 

 of one of the Ste. Dorothée breccias resembles the biotite of the al- 

 noites rather than the deep brown variety at Ste. Dorothée. It is 

 also noteworthy that the rocks connected with the breccias elsewhere 

 are very much altered while those at Ste. Dorothée are quite fresh. 

 It is, therefore, supposed that these breccias like those at the White 

 Horse Rapids four miles to the south and those at La Trappe are 

 associated with a much more basic rock than the fourchite at Ste. 

 Dorothée, although this rock has not yet been discovered in this 

 locality. 



Relationships of the Alnoitic and Associated Rocks 



The normal types of the basic intrusives described above, with 

 the exception of the basalt at Ste. Dorothée, are very closely related 

 to one another. To these may be added the various localities described 

 by Harvie in which breccias occur associated with alnoitic dykes and 

 also the monticellite alnoite at Isle Cadieux, described by Bowen, and 

 the alnoite at Ste. Anne de Bellevue, described by F. D. Adams. All 

 of these are of somewhat different mineralogical composition, as may 

 be seen by the following table : 



Essential Constituents of Alnoites and Associated Rocks of Western Quebec 



