58 GEOLOGY OF MOOSE RIVER GOLD DISTRICT — WOODMAN. 



irregular in shape generally have their longer axes parallel with 

 the stratification. This was noted in all the slides in which the 

 latter was visible. The secondary minerals in these rocks do 

 not appear to form distinct bands giving cleavage or schistosity ; 

 and altogether the quartzites are quite massive when viewed 

 .under the microscope. 



But the slates are strongly cleaved, as well as slate laminae 

 in the whin. The fissility results chiefly from a rearrangement 

 of the kaolin, so that it lies in the cleavage bands rather than in 

 those of stratification. It is aided, but probably not formed, by 

 secondary minerals. Those rocks which in the hand specimen 

 appear most schistose, even the fine knotted schists mentioned 

 above, have only a slightly larger amount of secondary material, 

 the schistosity being due to a microscopical wavy cleavage that 

 seems to be cronulated without much regard to the knots of 

 quartz or other minerals. It is this crenulation which, in part 

 at least, gives the lustrous and silky appearance to the schists. 

 Pyrite never influences cleavage. 



Glacial pressure affected that part of the cleavage lying near 

 the surface in many places. The best example is along the 

 trenches in areas 30 and 71. Here all the top of the rock is in 

 places crushed into a mass of small cleavage plates, which were 

 gradually worked into the glacial gravel by the onward motion 

 of the ice. Where this breaking up was not so complete, an 

 overturning of the cleavage from a south to a north dip haa 

 taken place, accompanied by a great increase in the fissility of 

 the rock ; due in part to the ice strain, and in part to a later 

 water circulation. 



RECENT WEATHERING. 

 The weathering of the sediments consists largely of changes 

 in the sulphides. The pyrite and arsenopyrite alter, in some 

 cases giving sulphates, and in others not. As a whole the rocks 

 stain little by this process. In some places the angular cavities 

 left by the crystals are quite abundant. 



