GEOLOGY OF MOOSE EIVER GOLD DLSTRICT — WOODMAN. 55 



systems. Perhaps the most abundant run about north and south 

 magnetic, but tliey are not persistent for more than a few yards. 

 For the most part they neither aid nor retard open or under- 

 ground development. One of the best joint planes forms the 

 face of the westward spur in the east side of the quarry on area 

 74 (pi. 8, tig. a). No veiuing or mineralization has been seen 

 along most of these fractures, except a few cases of pyrite in- 

 crustations of a crystalline nature. 



METAMORPHISM. 



Dynamic character. — No intrusives are exposed in or near 

 Moose River, the nearest granite — the Tangier massif — lying 

 some miles south ; and all the metamorphism in this field is of 

 the dynamic type. In brief, it consists of the microscopic redis- 

 tribution of material in both types of sediments, the alteration 

 of shales into clay slates by cleavage, and of sandstones into 

 quartzites, and later into arenaceous slates by cleavage ; and 

 finally, further local change of slates of both kinds into schists. 

 These alterations are not uniformly distributed geographically, 

 even in the same stratum. This may have a very direct bearing 

 upon the interpretation of the highly raetomorphosed rocks at 

 the western end of the province. 



Secondary ^minerals. — The cement of the quartzites is partly 

 secondary silica, partly calcite, with a small amount of iron 

 oxide in rocks taken from near the surface. The larger part 

 appears to be calcite. It is probable, from the appearance of 

 the slides, that all the cement, as it is at present, is secondary. 

 Biotite and muscovite are abundant in some slides ; and a part, 

 perhaps most, of the mica is secondary. None of the quartz 

 grains show a direct elongation in the direction of cleavage. 



The clay slates do not normally show any of these minerals. 

 On the other hand, chlorite is found to a much greater extent 

 than in the quartzites. The color of the slates depends in part 

 upon this, but yet more upon original conditions of deposition. 

 The rocks have, abundantly distributed in the direction of cleav- 



