166 THE VERMILION IRON-BEARING DISTRICT. 



short distance to the south. These exposures, therefore, besides offering 

 opportunity for a study of the general characters of the greenstone, are 

 very favorable for a study of the metamorphism of the greenstone into the 

 amphibole-mica-schists, Avhich, as seen in isolated exposures, in many cases 

 offer little evidence of their derivation from the greenstones. 



POSSIBLE TUFFS ASSOCIATED WITH THE GREENSTONES. 



Reference has already been made to the fact that, associated with the 

 greenstone, we not uncommonly find masses of tuffaceous-looking rocks, 

 which, since they show no characters clearly indicative of sedimentation, 

 have been included with the greenstones as interbedded tuff deposits. 

 Included in this category are deposits occumng at the following places:' 



North 200 paces, west 1,950 paces from southeast corner sec. 17, T. 



62 N., R. 13 W. 



North 600 paces, west 1,000 paces from southeast corner sec. 30, T. 



63 N., R. 11 W. 



North 1,930 paces, west 1,000 paces from southeast corner sec. 3, T. 

 63 N., R. 13 W. 



North 2,000 paces from southeast corner sec. 3, T. 63 N., R. 13 W. 



On east shore of large lake in T. 62 N., R. 14 W., just south of the 

 east-west section line between sees. 25 and 36. 



Another area is-that occurring 1,650 paces north of southeast corner 

 sec. 20, T. 63 N., R. 10 W. Here the tuffaceous rock has been sheared 

 and where most schistose, with the schistosity striking N. 70° E., black 

 jasper has been infiltrated. 



EVIDENCES OF VOLCANIC CHARACTER. 



Beginning about 1,500 paces north of the southeast corner sec. 3, T. 

 62 N., R. 12 W., and extending south along the section line to the 

 quarter post, there are numerous exposures of dark-gray to green rocks 

 which have irregular lines running through them, and possess a more 

 or less perfectly preserved amygdaloidal and ellipsoidal structure. The 

 lines refeiTcd to are thought to be flowage lines. These, in connection 

 with the other structures mentioned, seem to be fair proof of' the volcanic 

 character of the rocks. These volcanics are penetrated by dikes of granite 

 which vary in size from very small ones an inch or more in width to some 

 having a width that is measurable by yards. The rocks themselves are 



