114 TROCEEDINGS OF THE ACADEMY OF [1890. 



passes into kaolin, while in some places it appears to be changing 

 into a serpentine-like mineral. 



I have described the region thus minutely because my conclusions 

 in regard to it differ from Mr. Hall's, and because the exposures at 

 any one place are not convincing. 



Mr. Hall's theory requires a lower region of schists, lying at low 

 angles, overlaid by the serpentines in one or more synclinal basins. 

 I have been unable to find an instance of a dip under 70°, while there 

 are hundreds 70° and upwards. 



AVhere the schists and granulites, and the serpentines, occur in con- 

 tact, and both walls can be seen, one is included in the other in a mode 

 precluding any theory of synclinal or anticlinal folding and to make 

 interbedding the only possible explanation. 



Whether the granulites are all stratified, or whether some of them 

 are igneous is a more diflicult question. It is certain that some of 

 them are stratified, as in the cut west of Elwyn and that east of 

 Glen Riddle station, but others, as on the east side of Chrome Run 

 and in Crump's quarry, have a plutonic asjiect and resemble very 

 closely the granulite dykes which penetrate the chrysotile bearing 

 serpentines near Black Lake and Thetford P. Q. At this place the 

 explorations for chrysotile have well exposed the rock, which Dr. 

 Ells of the Geol. Survey of Canada informs me is an altered intrusive 

 diorite. Penetrating the serpentine are frequent dykes of granulite 

 from a foot wide upwards, with the dyke character distinctly 

 marked. The serpentine being hard and undecomposed, the eflfect 

 of the dykes was apparent in slickensides and slaty, fibrous and 

 jointed structure. Two small dykes which I examined were de- 

 composed next to the serpentine and the whole appearance was 

 almost a counterpart of that shown at Crump's quarry at Mineral 

 Hill above described. Of these exposures Dr. R. W. Ells writes. 



. " In all these areas (Thetford, etc.) the serpentines are closely associated with 

 the dtorites, of some portions of which they are undoubtedly, in part at least, an 

 alteration product, in contact with the black Cambrian slates on the one hand, and 

 with hard whitish granulite on the other. The latter, which sometimes assumes 

 the nature of a granite, frequently occurs in huge masses, or dykes, cutting the 

 serpentine rocks both here, and at Black Lake and Thetford." Geol. Can. 1886, 

 J. 29. 



Speaking of the asbestus (chrysotile) mines of Belmine, he says : 



"The serpentine is associated with considerable masses of whitish granulite 

 * * * * ii^ places * * * * a true granite. This appears in places to 

 cut the serpentine after the manner of true dykes. * * It is presumable that in 

 most cases at least the rock is to a great extent an alteration product of some form 

 of dioritic rock rich in olivine." Id. p. 43. 



