00"7 



TWO ISLANDS NEAR THESSALON. 32 



has only covered the southeastern boundary, and it may be well to define 

 the junction at a few other points. 



# 



ROCKS OF THE CONTACT BETWEEN CARTIER AND STRAIGHT LAKE STATIONS. 



Between Cartier and Straight Lake stations, on the Canadian Pacific 

 railway, there is an irregular patch or outlier of Huronian completely 



enclosed by gneiss and granite. The junction between the two rocks is 

 seen just beyond Straight Lake station. The gneiss is very massive, 

 coarsely crystalline, and very distinctly foliated, while the Huronian is 

 represented by dark greenish-gray feldspathic shale and sandstone. 

 The foliation of the gneiss in general corresponds with the strike of the 

 shale, which is S. M° E., dip S. 6° W. <55°. The sandstone and shale 

 are altered into very glossy mica schist near the junction, become con- 

 torted and exhibit interlaminated nodose lines of quartz, veinlike in 

 origin. These lenses of quartz are clearly secondary and in every case 

 cause a bulging of the enclosing rock by their introduction, and have 

 doubtless been formed by the silica set free in the genesis of the gneiss. 

 Feldspathic intrusions are commonly met with in the sandstone and 

 shale a considerable distance from the line of junction, while patches of 

 the sedimentary strata have been caught up in the mass of the gneiss. 

 Epidote is abundant, especially near the junction. 



TWO ISLANDS NEAR TIIESSALO.X. 



Contact previously described by Others. — During the early part of October 

 last an examination was made of the contact as exposed on two islands 

 close to the north shore of Lake 1 [uron, about five miles east of Thessalon. 

 As the water was rather high, only a few feet of the junction was exposed 

 in each instance. The contact here was first described by Irving* in 

 1887 and later, in 1892, by Messrs Pumpelly and Van Hise.j but as the 

 author's conclusions differ somewhat from those expressed by the above- 

 named writers it was thought advisable to bring them forward at this 

 time. 



Difference in the Conclusions <>f the Author and other Writers recited. — The 

 Laurentian or basement complex, as it has been called, is here repre- 

 sented by a granite gneiss through which has been intruded large masses 

 and dikes of a dark greenish-gray, fine-grained diabase. This appears to 

 be in turn cut by a flesh-red granite, although the frequent absence of 



'Am. Jour, of Science, vol. xxxiv, pp. 207-216. 

 flbid., vol. xliii, pp. 224-232. 



