Temagami-Temishaming District, Ontario. 31 



If it be admitted that the drainage system is the outward 

 revelation of an inward one of rock-fracturing, weakness, and 

 probably to some extent displacement, then the network ap- 

 pears like tlie result of Daubree's experiment on the induction 

 of jointing by torsional warping.* It would seem natural to 

 refer the lakes in part to minor warps or displacements of pre- 

 existent channels along these lines of weakness, although in 

 part they are probably due to morainal dams and to glacial 

 scour. 



Tivie of Warj)ing. — If such warping with fracturing has 

 taken place, the questions naturally arise as to when it occurred 

 and if it is still continuing. The region has, as yet, not been 

 studied in sufficient detail, with such questions in mind, to afford 

 decisive answers. Some facts there are, liowever, which have 

 a bearing on these points. Thus Millerf points out that the 

 mineral veins follow closely the same systems as the water 

 courses, and the deduction from this must follow that they are 

 either contemporaneous or later than the formation of the frac- 

 ture system. But the silver veins have been glaciated and con- 

 sequently the fracture system is pre-glacial. Miller indeed 

 refers it to post-middle Huronian time, this view being based 

 on the hypothesis that the deposition of the ores was the result 

 of the intrusions of diabase which are referred to this period. 

 But inspection of the maps shows that the larger elements of 

 the fracture systems, as indicated by the drainage lines, pass 

 through these diabases as well as the older rocks. A careful 

 study of the Niagara group, and especially of its contact with 

 the older rocks, may throw much light on this question. 



Whether the crustal movements here assumed continued 

 after the glacial period and are still going on is a problem which 

 demands further investigation. Miller;}: states that post-glacial 

 faulting can be proved to have taken place. A noticeable fea- 

 ture of the region are the open torsion cracks and joints seen 

 on glaciated rock-surfaces which have not been filled or eroded. 

 They have been illustrated by Miller. While these are indi- 

 cations, more positive evidence would come, as has been previ- 

 ously suggested, from the canting of the lakes and exposures 

 of uplifted beaches and marks of wave-work on shores. If 

 such canting is pre-glacial these would be largely swept away, 

 but if warping has continued into post-glacial times or been 

 renewed, the evidence to prove it can undoubtedly be gath- 

 ered. § 



*Geologie Exp^rimentale, p. 510, 1879. 



t Loc. cit., p. 38. X Loc. cit., p. 38. 



§ Since this paper was presented, and at the time of putting it in form for 

 publication, the program of papers to be read at the Boston meeting of the 

 Geol. Soc. Amer. has been received. In this is listed a paper by Dr. Robert 

 Bell entitled the '• Diversion of the Montreal Eiver," and in the attending 



