286 THE VERMILION IRON-BEARING DISTRICT. 



near an underlying mass of the same kind, and when, moreover, we find 

 beds of grits and slate alternating with the conglomerate, all of these 

 showing every gradation into one another and possessing both true bedding 

 and false bedding, the only satisfactory conclusion we can form concerning 

 the origin of these rocks is that they are true clastic conglomerates of 

 sedimentary origin. This mode of origin seems so obvious that its 

 statement appears almost uncalled for, and it is made only for the reason 

 that a strong argument has been made by previous students of the rocks 

 of this area for the brecciated origin of these conglomerates." Reference 

 has already been made in previous pages to the formation of pseudo-con- 

 glomeratic rocks from the granites of Vermilion Lake by dynamic processes. 

 The first description of these pseudo-conglomerates (friction conglomerates) 

 and the correct explanation of their origin was given by Smyth and 

 Finlay in the article above referred to. They made the error, however, 

 of attributing this method of formation to all of the conglomeratic-looking 

 rocks of that part of the lake and adjacent shores which they studied, 

 including great masses of true normal conglomerates occurring in great 

 abundance on Stuntz Island, Stuntz Bay, and elsewhere. These rocks, it 

 is true, are intimately associated with the pseudo-conglomerates, but in 

 most places may be readily separated from them. That the true conglom- 

 erates were unquestionably included with the pseudo-conglomerates is 

 shown by the fact that reference was made to the conglomerates occurring 

 on Stuntz Bay and Island as examples of pseudo-conglomerates,* whereas 

 in reality they are typical sedimentary conglomerates in which may be 

 observed the characters referred to above as proving indisputably their 

 sedimentary origin. 



THICKNESS. 



The bedding in the coarse conglomerate is poor, but grows more 

 distinct as the grain gets finer until, as in the rocks here called graywackes, 

 it becomes very distinct. It is, however, generally so obscure that it has 

 not been possible to determine it with great accuracy and frequency. 

 Moreover, the rocks have been extensively folded, and considerable redupli- 

 cation — which it has not been practicable to determine — may have taken 



"Geological structure of the Vermilion range, by H. L. Smyth and J. Balph Finlay: Trans. Am. 

 Inst. Min. Eng., Vol. XXV, 1895, pp. 610, 629. 

 6 Op. cit, p. 612. 



