256 THE VERMILION IRON-BEARING DISTRICT. 



mentioned. They are Ijelieved, however, to belong- to the same general 

 period of intrusion. 



On the hills south of Mud Creek Bay and south of Mud Creek itself 

 there are also numbers of dikes of granite and porphyry which cut the ellip- 

 soidal greenstone. 



The following are other localities where the acid intrusives cutting the 

 greenstone may be studied: 



North 1,000 paces, west 1,000 paces, from southeast corner of sec. 9, 

 T. 62 N., R. 14 W. Here a granite-porphyry containing large phenocrysts 

 of quartz cuts through a dense greenstone forming the bluff overlooking the 

 swamp to the south. A similar dike is to be found at north 1,650 paces, 

 west 950 paces, from southeast corner of sec. 21, T. 62 N., R. 14 W. 



West 1,000 paces, from southeast corner of sec. 10, T. 62 N., R. 14 W. 

 Here the porphyry is fine g'rained, and has a dense groundmass. 



North 200 paces, west 100 paces, from southeast corner of sec. 27, T. 62 

 N., R. 14 W. This is one of the feldspathic porphyries. 



Relations of the acid intrusives to the Soudan formation. — On the bold, bare 

 hills of ja.sper, at a point north 270 paces, west 200 paces, from the south- 

 east corner of sec. 7, T. 62 N., R. 15 W., a dike of granite-porphyry 20 paces 

 wide, containing large phenocrysts of quartz, cuts through the jasper. It 

 cuts across the strike of the bands of jasper in places and runs out into the 

 jasper in small string-ers, and also includes fragments of the jasper. The 

 grain of the intrusive rock is seen to be noticeably finer along the contact 

 of the small stringers than it is in the main mass of the granite. Reference 

 has already been made to the granite dikes found cutting the jasper in sec. 

 1, T. 62 N., R. 15 W. In both of these places the relations are perfectly 

 clear. 



Contacts between these two kinds of rock were not found at many 

 places, but where they were observed the relationship was clearly shown. 

 At 1,125 paces north, 1,300 paces west, of the southeast corner of sec. 20, 

 T. 62 N., R. 14 W., a dike of feldspar porphyry cuts through the jasper and 

 the associated green schist. This porphyry includes large fragments of the 

 jasper and small ones of the g-reen schist, showing' conclusively its relations 

 to them. In places these fragments are so numerous that the rock distantly 

 resembles a cong'lomerate. 



