120 THE VERMILION IRON-BEARING DISTRICT. 



greenstones, extends from the northern part of Vermilion Lake through 

 Basswood Lake to the northern side of Hunters Island. The southern 

 arm, consisting of Lower Keewatin green schists and other schists, pene- 

 trated by the g-ranite of the Griants range, extends from Pokegama Falls on 

 the southwest toward the northeast, until cut out by the encroachment of 

 the gabbro from the south. The Upper Keewatin consists very largely of 

 conglomerates, but also includes graywackes, argillites, quartzites, and 

 jaspilites, in general coarser than those of the Lower Keewatin. Volcanic 

 rocks are less important than in the Lower Keewatin, although still 

 present. There is no general order of succession in the Upper Keewatin 

 excepting that it can be said that it is in general conglomeratic at the bottom. 



After Upper Keewatin time both the Lower and Upper Keewatin were 

 subjected to another folding, the axis of which had a general parallelism 

 with the earlier folding, with the result that the Upper Keewatin lies in 

 narrow sjaiclines in the Lower Keewatin and in places is nearly or quite 

 vertical. 



Associated with the Keewatin rocks are granites of at least two periods 

 of intrusion, one later than the Lower Keewatin and one later than the 

 Upper Keewatin. The later granite is believed to be represcmted b}^ the 

 higher parts of the Giants range and the Snowbank Lake granite. The 

 earlier granite is represented by the granites at Kekequabic (^acaquabic) 

 Lake, Saganaga Lake, Basswood Lake, Burntside Lake, Veiunilion Lake, 

 Lac la Croix, and Kabetogama Lake. The origin of the granite is dis- 

 cussed and the same conclusions reached as in a previous article." 



The Taconic. — This is uncouformabl3^ above the Keewatin rocks. It 

 comprises the Animikie and Keweenawan divisions. 



The Animikie rocks enter the State at Pigeon Point, run westward along 

 the international boundary to the eastern part of sees. 22 and 27, T. 65 N., 

 R. 4 W. They reappear again south westward from Birch Lake on the north- 

 west side of the gabbro mass, and thence continue along the south side of 

 the Giants range, constituting the Mesabi iron series, to Pokegama Falls. 

 The higher parts of the Animikie are best developed toward the east while 

 the lower parts are best developed toward the west. 



"The origin of the Archean igneous rocks, by N. H. Winchell: Proc. Am. Assoc. Adv. Sci., Vol. 

 XLVII, 1898, pp. 303, 304 (Abstract). Also Am. Geologist, Vol. XXII, 1898, pp. 299-310. Summar- 

 ized Jour. Geol., Vol. VII, 1899, p. 194. 



