CONCLUSIONS AND FACTS SUPPORTING THEM. 331 



6. The general character of the rock itself, which in appearance and 

 behavior lias far more resemblance to an ordinary eruptive granite with 

 a foliated texture than an altered sedimentary rock. Sir , \V. E. Logan 

 himself, in his notes of its occurrence on Lake Temiscaming, invariably 

 refers to it as " gneissoid syenite," and the later Walter McOuat, of this 

 survey, although he describes in his printed report an intrusive mass of 

 syenite cropping out on Round lake at the head of Blanche river (north 

 of Lake Temiscaming), yet on his accompanying manuscript map colors 

 it as Laurentian gneiss, evidently deeming it of similar character and 

 origin. 



Everywhere this Laurentian gneiss is thoroughly crystalline and pre- 

 sents no structure that in any way suggests an alteration of clastic con- 

 stituents. In many places the gneiss can be traced into obscure or non- 

 foliated areas which present the ordinary characters of true irruptive 

 masses. The boundaries of these patches are very often illy defined and 

 they pass insensibly into the ordinary gneiss. The frequent occurrence 

 of dikes and masses points out a sequence of irruptions whose order it is 

 often possible to determine over limited areas. The parallel arrange- 

 ment of the component minerals and the alternation of coarser and finer 

 bands often suggest the How structure of certain eruptive rocks. The 

 gneiss usually shows only slight evidences of secondary pressure, seen in 

 the occasional dislocation of the feldspar crystals, in shearing and in 

 cataclastic structure which has sometimes been developed. The Huro- 

 nian schists, on the other hand, present abundant evidence of secondary 

 pressure in the development of pronounced cataclastic structure, the 

 presence of numerous shear planes, and the squeezed or drawn-out char- 

 acter of the quartz grains. Mr Ferrier, however, in his examination of 

 two thin sections of the granitic gneiss to the south of Daisy lake, discov- 

 ered the presence of most intense cataclastic structure, which must have 

 been induced in the rock subsequent to its cooling, but as the schist in 

 contact with the gneiss also exhibited this extreme phase of cataclastic 

 structure, and as the stratified rocks in the immediate vicinity are so 

 highly altered as to preserve hardly a trace of their original clastic struct- 

 ure, we may, perhaps, safely assume that both gneiss and schist have 

 been subjected to this same immense pressure at a time subsequent to 

 their coming together in their present position. 



The Huronian system, therefore, may be regarded as the oldest series 

 of sedimentary strata of which we have at present any knowledge in this 

 region. The original sediments must have been laid down on a firm 

 floor, whose composition, judging by the character of the Huronian rocks, 

 must have been closely analogous to granite. It was doubtless the 

 fusion and subsequent recrystallization of this granitic floor that gave 



