450 THE GEOLOGY OF MINNESOTA. 



[Quartzyte. Diabase. 



than to the dike No. 605 in contact with which they are found at the south side of 

 the point. This would imply the existence of a fault at the north side of the dike 

 No. 605, running parallel with it. (Compare figure 100, vol. iv, report on the Pigeon 

 Point plate; repeated above by figure 30.) N. H. w. 



No. 613. QUARTZYTE. (Metamorphosed.) 



Pigeon point. West side of the little bay at the south end of the " Little portage." 

 Ref. Annual Keport, ix, pages 69, 70; Annual Report, x, page 58. 



Meg. Rock is gray, but otherwise appears much like some of the foregoing. 



Mic. There is a trace of the clastic origin of some of the quartz grains in this 

 slide. They have interior forms outlined by lines of impurities, on which later 

 growth of quartz has taken place, both parts extinguishing at the same instant. 



One section. 



Age. Animikie. N. H. w. 



No. 614. DIABASE. 



Pigeon point. At the extremity of the west point of the little bay from which the " Little portage" starts, 

 south side of Pigeon point. 



Ref. Annual Report, ix, page 69; Annual Report, x, page 58. 



Meg. Fine grained, nearly black, resembling No. 604. 



Mic. The rock consists of the elements of the diabases of the country, at least 

 auyite, microlitic feldspars, the former being cotemporary or earlier in date than the 

 feldspars, and of magnetite. 



One section. 



Age. Sill(?) in the Animikie. 



Remark. The outward resemblance of this rock to No. 604, and its similarity of 

 position with respect to the little bay, one on either of the points that enclose the 

 bay, would lead one to consider them of the same rock mass. But one is a hardened 

 clastic, and the other is a finely crystalline irruptive. This idea would not be 

 weakened by the fact that a coarser diabase dike cuts each of them. The dike which 

 cuts this point, however, has not the direction of that cutting the other point, but 

 runs into the lake southeast, while the other seems to run into the bay, lying to the 

 north of this. This dike, moreover, is about one-third the width of that. N. H. w. 



No. 615. DIABASE. 



Pigeon point. Dike twelve feet wide which cuts No. 614 above. 



Ref. Annual Report, ix, page 69; Annual Report, x, page 58; Bulletin ii, page 108. 



Meg. Medium -grained diabase. 



Mic. This rock, which is rather fresh, shows, like numerous others that have 

 been examined, two generations of augite, viz.: one is earlier than the plagioclases, 

 and is considerably decayed, and the later is fresh and ophitic, though occasionally 



