GEOLOGY OF MOOSE RIVER GOLD DISTRICT — WOODMAN. 57 



Slickensides along cleavage planes are abundant, usually 

 taking the form of a smooth deposit of chlorite. In some open- 

 ings there is a distinct serration of the contact of horizontal or 

 low-lying strata. Examination has shown it to be due in a few 

 instances to creuulation of the laminae, developed so far as to 

 give strain-slip cleavage. But this is only in slate. Between 

 slate and whin, as in the quarry on areas 73 and 74 (pi. 8, fig. 

 ^; and 11, tig. b), it is the result of slipping along ordinary 

 cleavage planes whi ch happen to be nearly or quite perpendicu- 

 lar to the stratification. In this quarry the quartzite does not 

 ■show cleavage well, except at the east end. This applies especi- 

 -ally to the stratum overlying the Jo. Ta\dor belt. In general 

 through the zone occupied by the subsidiary anticline, the 

 preponderance of pelite has allowed a good fissility to be 

 ■developed. 



In the quarry on areas 76 and 77, the same stratum appears 

 in different places as a well cleaved slate and as a fine knotted 

 schist. As a whole the cleavage in this district ignores the 

 small crenulations of the slate. When, however, it comes down 

 on top of a corrugation in a quartz vein encased in slate, it often 

 curves, sometimes parting to one side and the other, because the 

 slate yields readily while the quartz is brittle (pi. 8, fig. b, and 

 15). This curving was well shown in 1897 in the west end of 

 the quarry on area 131, on a large scale. 



In many specimens pyrite is seen lying in the cleavage 

 planes, but quartz veins never. This pyrite is not crystalline 

 or massive granular, however, but always stretched into a thin 

 plate, or at least so far as much to distort the shape of the orig- 

 inal crystal. This proves conclusively the later date of the 

 cleavage than any of the sulphide concentrations. Indeed, cleav- 

 age and jointing were the last great dynamic changes in the 

 sediments. Arsenopyrite has resisted stretching, for the most 

 part. 



In thin section the quartzites show little appearance of cleav- 

 age. The quartz grains not only are not elongated, but when 



