PRE-KEWEENAWAN FORMATIONS 693 



ARCHEAN SYSTEM 



Rocks of Archean age are confined, in the territory under dis- 

 cussion, to the fine-grained chloritic schists (Keewatin) lying un- 

 conformably beneath the Sunday quartzite in T. 47 N., R. 44 W. 

 In the maps accompanying the reports of the United States Geo- 

 logical Survey the hornblende and mica schists lying south of the 

 Huronian sediments in T. 47 N., R. 43 W., are included in the 

 Keewatin, and the extensive area of acid intrusives, here termed 

 the Presque Isle granite, is placed in the Laurentian. We believe 

 that the Presque Isle granite intrudes the Middle Huronian and that 

 the schists in T. 47 N., R. 43 W., heretofore correlated with the 

 Keewatin, are phases of the Palms formation, the metamorphism 

 being induced by granitic intrusion. 



THE ALGONKIAN SYSTEM 

 HURONIAN SERIES 



Lower Huronian group 



The Lower Huronian comprises two formations, viz., the Sun- 

 day quartzite and the Bad River limestone, exposures of which 

 are limited to the south half of sections 17 and i8,T.47N.,R. 44W, 



The Sunday quartzite is grayish white to pink, about 150 feet 

 thick, and carries a thin basal conglomerate holding fragments of 

 the underlying Archean (Keewatin) greenschist. It incHnes 

 gently (30°) across the almost vertical plane of schistosity in the 

 subjacent schists. 



The Bad River formation is a cherty dolomite about 400 feet 

 thick. It is conformable through gradational phases with the 

 underlying Sunday quartzite and is unconformably overlain by the 

 Upper Huronian (Animikie) group. 



Upper Huronian (Animikie) group 



The Animikie group is represented by a basal quartzite 

 (Palms), an iron-bearing member (Ironwood), volcanic conglome- 

 rates, breccias and flows, and intrusive granite and greenstone. 



On recent maps of the United States Geological Survey the 

 Palms and Ironwood formations are carried eastward as cartographic 



