PETROGRAPHICAL CIIARACTRK OF THE KONA DOLOMITE. 251 



the Ajibik quartzites subseciuently described, with the excei)ti(>u that they 

 are more or less dolomitic. 



The foreo-oing study of the thin sections of the Kona formation shows 

 that it has been shattered throughout. From the fiekl observations it was 

 apparent that the formation had been much broken b)^ dynamic action, but 

 the completeness of this shattering and brecciation was appreciated only 

 by a study of the thin sections, every one of the numerous slides showing 

 these phenomena to a greater or less degree. It thus appears that not a 

 half-inch cube has escaped. It is believed that this indicates that the rock 

 when folded Avas not buried under so great a load as to be beyond the 

 sustaining power of the rocks. Upon the other hand, since there are no 

 prominent faults, and since the formation as a whole is folded in a com- 

 plicated fashion, retaining its continuity, it is thought that it was buried 

 under a considerable thickness of strata. It was therefore in the zone of 

 combined fracture and flowage. 



KELATIONS TO ADJACENT FORMATIONS. 



The Kona dolomite varies through a slate into the Mesnard quartzite 

 below. This slate appears to be a thin, persistent formation. Its tliickness 

 varies from less than 30 feet to 100 feet. In many places it appears thinner 

 than this smaller number, but it is only at a few places that the exact contact 

 ]t)etween the slate and the formations above and below it can be seen, 

 there usually being, however, sufficient room for the slate belt between the 

 quartzite and the dolomite. This slate may be well observed at Mount 

 Mesnard, where it forms a little valley separating tlie quartzite peak on the 

 north from the marble peak on the south. The slate may also be well 

 seen just west of Wabassin Lake, in sec. 2, T. 47 N., R 2.5 W., where 

 the westward-plunging syncline of the Kona formation causes the slate to 

 appear innnediately beneath the limestone. This belt of slate, which was 

 once a shale, probably marks the time of deepening waters, when the con- 

 ditions favorable to the deposition of a sandstone changed to those favorable 

 to the formation of a limestone. 



Above, the dolomite, by a lessening of the calcareous constituent, 

 gradually passes into the Wewe slate. The appearance of this formation 



