CANADA 



343 



the same distance from the latter ; but it is very much disturbed by intrusive 

 granite and greenstone, and, although there are great exposures of rock, it is 

 very difficult to make out hcnv the stratified portions are related to one an- 

 other. The gneiss extends to the vicinity of a small stream about a mile and 

 a half above Les Grandes Sables, and what is supposed to be the lowest IIu- 

 ronian mass of that part occurs about half a mile above the stream. It consists 

 of a grey quartzite which abuts against one mass of gneiss and runs under an- 

 other, and appears to be nmch broken by and entangled among the intrusive 

 rock ; but judging from a transverse measure in one part, its thickness would 

 not be far from 500 feet." (I. c, p. 55.) 



It would seem that licro the Huronian was found abuttiu'^ airainst 

 and underlying the Laurentian gneiss (granite). In none of the sec- 

 tious given do the conglomerates in the Iluronian appear to lie at the 

 base of t\w formation, but at varying heights in the scries. 



The exception referred to above is this : under the head of " Contact 

 of Laurentian and Huronian Rocks/' it is stated that in the upward 

 navigation of the Kaministiquia Eiver 



*' the first development of the Laurentian series occurs at the second port- 

 age, about half a mile above the Grand Falls. At the lower end of the port- 

 age, where tlie series makes its appearance, the rock resembles a massive 

 syenite, in some ]);i.rts red and in others whitish, but is probably a hornblcudic 

 gneiss in wliioh the lamellar arrangement of the constituent minerals is ob- 

 scure, as the rock graibuLlly passes into such a gneiss. Resting on it conform- 

 ably there occurs a series of dark greenisli-bhie or greeuish4)lack slates, the 

 one rock passing almost imi)erccptibly into the other. The section occupies 

 upwards of a (quarter of a mile on the river bank, and at the upper end of it, 



as well as at the head of the portage, the dip is N. 54^ E At each 



rapid part of the river above the Grand Falls there is a greater or less develop- 

 ment of those rocks, nu^st frequeully presenting the more distinctly stratified 

 part of the gneiss. The best exposure of the slates is at the Three Discharges, 

 about four miles above the Grand Falls, where the rocks are observed to pass 



from the gneiss to tlie slate Towards the bottom, near the junction 



with gneiss, the slates are of a bluish and occasionally of a brownish color." 

 (I. c, pp. 64, 05.) 



It Avould then appear that Huronian in the only localities, except one 

 problematical one (/. c, pp. 52-54, 703), in which it had been seen in 

 contact with the Laurentian, was conformable with and passed almost 

 imperceptibly into, or else underlaid, the Laurentian. 



An intrusive granite is said to occupy 



" a considerable area on the coast of Lake Huron, south of Lake ?akowa<?aminct. 

 It there breaks through and disturlja the gneias of the Laurentian series, and 





