TRANSACTIONS OF SECTION C. 037 



of Lake Superior in general lithological character, recur in many places almost 

 througbout the whole vast area of the Protaxis, on both sides of Hudson Bay, and 

 northward to the Arctic Ocean, resting upon the Archaan rocks always in com- 

 plete discordance, and lying generally at low angles of inclination, although often 

 affected by great faults. The surface upon which these rocks have been deposited 

 is that of a denudation-plane of flowing outline, not differing in any essential 

 respect from that characterising parts of the same great plateau where there is no 

 evidence to show that any deposition of strata has occurred since Archtean time. 

 Mr. Low, indeed, finds reason to believe that even the great valleys by which the 

 Archfean plateau of Labi'ador is trenched had been cut out before the general 

 subsidence which enabled the laying down of Animikie rocks upon this plateau to 

 begin. The area over which these observations extend, thus in itself enables 

 us to affirm that the unconformity existing between the Animikie or Keweenawan 

 (as the case may be) and the Archasan is of the first order.' It may be comparesl 

 with that now known to occur between the Torridonian of Scotland and the under- 

 lyinff rocks there, and is evidenced by similar facts. 



If the structural aspects of the Archaean rocks of the Protaxis are considered, 

 the importance of this gap becomes still more apparent. We find long bands of 

 strata referable to the Huronian and Grenville Series, occupying synclinal troughs,, 

 more or less parallel to each other and to the foliation of the Fundamental Gneiss, 

 the strata, as well as the foliation, being in most cases at high angles, vertical, or 

 even reversed. This structure is precisely that which would be discovered if a 

 great mountain system, like that of the Alps, were to be truncated on a plane- 

 sufficiently low. Analogy thus leads to the belief that the Protaxis was originally, 

 as Uana has suggested, a region of Appalachian folding, differing only from 

 more modern examples of mountain regions of the same kind in its excessive width, 

 which is so great as to render it difficult to conceive that crustal movements oi 

 sufficient magnitude to produce it could have occurred at any one period. It is^ 

 thus, perhaps, more probable that successive and nearly parallel flexures of th& 

 kind, separated by long intervals of rest, piled range upon range against the central 

 mass of the protaxial buttress subsequent to the Huronian period. In any case, 

 the rugged mountain region brought into existence when the corrugation still 

 evidenced by its remaining base occurred, was subsequently reduced by denudation 

 to the condition of an undulating table-land such as has been named a ' peneplain ' 

 by W. M. Davis — a surface approximating to a base-level of erosion. All this was 

 accomplished after the close of the Huronian period, and before that time at which 

 the first beds of the Animikie were laid down correlatively with a great subsidence. 

 It would be difficult to deny that the time thus occupied may not have been equal 

 in duration to that represented by the whole of the Palteozoic. 



If we approach this ruling unconformity from above, in the region of the- 

 Protaxis, we find the Animikie and Keweenawan rocks uncrystalline, except when 

 of volcanic origin, and resembling in their aspect the older Palaeozoic sedimeutS;, 

 but practically without characteristic organic remains, so fiir as known. In order 

 to bring ourselves into relation with the ascertained palajontological sequence, it is 

 necessary to go further afield, and in so doing we lose touch, more or less com- 

 pletely, with the stable conditions of the Archaean platform, and are forced to 

 apply indirectly such facts as it may be possible to ascertain in regions which 

 have suffered more recent and complicated disturbance. It is thus not turprising 

 that the taxonomic position of the Animikie and Keweenawan have been the sub- 

 ject of much controversy. It is not germane to the present discussion to enter at 

 any length into this question, nor into the value of the unconformity which appears 

 to exist between these two series. They have been classed collectively by Selwyn, 

 N. H. Winchell, and others as Lower Cambrian, and are provisionally mapped a» 

 such by the Canadian Survey. It is believed to be more in accordance with the- 

 general principles of geological induction to refer these rocks above the greati 

 unconformity to the Cambrian, for the time being at least, than to unite them 

 with the Huronian under any general term, or to erect a new system in which to 

 place them. In so doing it has been assumed that the Cambrian is the lowest 



' Of. Selwyn, Fcicnc^, Feb. 9, 1883. 



