OUTLINE OF THIS PAPER. xix 



forinity. Berorc, tlii^ deposition of tlio Pcnokee series the Southern Complex bad 

 reaelied its present completely crystalline condition and was reduced nearly to a base 

 level. Between the I'enokee series and the oveil,>-infi Keweenawan is a second veiy 

 considerable nncontttrmity, suflicient to luive removed in places the entire Penokee 

 succession. Alter the erosion and dei)osition of the Keweenaw series the. whole was 

 tilted toward the north, so astos'ive the])resent inonoclinal structure, after which the 

 Eastern sandstone was de|)osite(l upon the upturned series in its ]>resent horizontal 

 attitude. The Penokee series is limited on the east by the overlapjuug Eastern sand- 

 stoiie; on the west it was cut away by erosion before Keweenawan time, so that the 

 Copper-b(^aring series rests directly upon the Southern Complex. The Penokee series 

 proper is the equivalent of the Animikie, the Upper Original Huronian, and constitutes 

 a part of the Upper Hm-onian of the lake Superior region. The Cherty limestone is 

 the equivalent of some part of the Lower ITuronian. These two together are a part of" 

 the Algonkian, and the Southern Complex is AreUean, 



