76 GEOLOGY OF MOOSE RIVER GOLD DISTRICT — WOODMAN. 



The accumulation was on a sinking sea bottom, in a syncline 

 of deposition. The sediments at Moose River were among the 

 first of which we have knowledge, but evidently not actually 

 lowest in the series. The water may have contained lowly 

 organized life in some form, as shown by the slight amounts 

 of graphitic material in the rocks. 



With the great accumulation of strata came gradual lithifica- 

 tion, from pressure of overlying rocks and rise of the isogeother- 

 mal planes induced by the continual blanketing. It allowed 

 considerable secondary alteration of the shales and sandstones, 

 through increase in the solvency of the water of sedimentation, 

 and showing itself especially in the deposition of secondary 

 minerals. 



Increased lateral pressure of necessity accompanied increased 

 sinking of the sea bottom. There ensued more chemical action, 

 and the beginning of the east and west folding. Simultaneously 

 came the earliest deposition of vein material, along planes of 

 weakness, which were stratification planes. At last the folds 

 became marked in height, and greatest where plastic shale strata 

 were abundant ; and in the interstices between layers, and 

 occasional radial gashes upward from the folds, the veins and ore 

 had been gradually deposited, the latter in part remaining in 

 the adjacent country rock. 



Later, the greater rigidity of the rocks under pressure 

 allowed jointing and faulting. Pressure kept the fracture planes 

 tightly closed for the most part. Cleavage had been begun 

 earlier, in an incipent way ; but it had not developed into a 

 mechanical fissility until all the vein concentration had ceased. 



Denudation had been active on overlying beds, and finally 

 reached the horizon of Moose River. Evidence elsewhere shows 

 that by far the larger part of the denudation, which was the last 

 great event in the history, took place before the close of lower 

 Carboniferous times. 



