CANADA. 



549 



or nearly that of the strike of both series of rocks. The gneiss at this 

 distance has a strike of N. 72° E., and the green slate, just across the line 

 of junction, and only a few yards removed, N. 73° E." (Report on the Ge- 

 ology and Resources of the Region in the Vicinity of the Forty -ninth Parallel, 

 1875, p. 45.) 



Mr. Dawson continues : — 



"A mile still further eastward .... the Winnipeg River .... falls 

 northward, across the junction of the Laurentian and Huronian series, through 

 a narrow passage between rocky cliffs. At the fall, the rock is ... . much 

 hardened and of greenish colour ; dip N. 10° W. < 45°. Just below the foil, 

 the red gneiss again suddenly appears with a dip X. 18° E. 78° Not- 

 withstanding the close accordance of the strike of both series of rocks, and the 

 direction of the line of junction, the evidence appears to be nearly conclusive, 

 that the two formations are here brought together by a fault, with an e.xtensive 

 downthrow southward. If they are thus in contact merely by sharp folding, 

 the relative position must be reversed, as the dips would carry the slate series 

 below the gneiss." (/. c, p. 46.) 



Mr. Dawson in explaining this line of contact proceeds on the sup- 

 position that both formations are sedimentary, and hence offers the only 

 explanation he can and preserve the Laurentian in its supposed position. 

 Yet, so far as his descriptions go, one or both may be eruptive, which 

 would explain the observed facts just as well. It is a pity that, with 

 so much contact observed, he did not ascertain whether the contact was 

 the rubbing, grinding division-plane contact of a fault ; or the contact 

 produced by one rock laid conformably, or unconformably, upon an- 

 other, and both folded ; or the close-welded, altering contact of an erup- 

 tive rock. Had he carefully observed the phenomena of the contact, 

 he might have built on facts, and thus have been saved much useless 

 speculation. 



Of another locality Mr. Dawson remarks : — 



"The rocks .... belong, as I believe, to an area of much-altered Huro- 

 nian The actual junction between the two formations at this pomt is 



concealed by water, but they show a remarkable appearance of conformity, the 

 next rock seen, being a soft greenish slate, with a dip of S. 60° W. < 45°. 

 [The previously given dips of the Laurentian were S. 60° W. < 50°, and S . 45° 

 W. < 60°.] It is worthy of notice that similar apparently conformable jimc- 

 tions of Laurentian and so-called Huronian rocks have been noticed by Prof. 

 Bell, as occurring on the Albany River at Martin's Falls, and also in the neigh- 

 bourhood of "White River." (I. c, p. 29.) 



Mr. Bell in the Report of Progress for 1877-78, speaking of the 



