GENERAL CtEOLOGY OF THE DISTRICT. 



469 



It has been seen, that above the Cherty hmestone of the Penokee dis- 

 trict is ail erosion interval and perhaps a considerable strnctnral break. lu 

 the Animikie district we know of no equivalent to this member, and in 

 what follows it is excluded from the discussion. The Penokee and the 

 Animikie rocks have a parallelism in litholog-ical characters which is 

 remarkable. This parallelism lias ali'eady been discussed, l)ut the main 

 facts are here repeated. Not <:»nly is there a general likeness between the 

 specimens from the two -districts, but almost every phase of rock from the 

 Animikie series can be matched by specimens from the PenoTsee series. 

 In the Animikie district the formations underlining the iron-bearing belt are 

 not extensively exposed, and consequently little is known of the Animikie 

 equivalent of the Quartz-slate of the Penokee series. But along the lower 

 Current river, near Port Arthur, Ontario, occur quartz-slates underlying the 

 Iron-bearing member which resemble certain phases of the Penokee quartz- 

 slate. Beginning with the iron formations, the parallelism between the two 

 series is almost exact. The irony beds upon Gunflint lake, where are found 

 the best known exposures of the formation, are in their lower parts jasper, 

 magnetite-actinolite-schist, and cherty ferruginous rocks containing more or 

 less iron carbonate. Higher up are thick deposits of thinly bedded cherty 

 iron carbonate. All these varieties of rock are found in the iron formation 

 of the Penokee series, and at many places the order of succession is the 

 same. Above the iron-bearing belt in both districts is a great thickness of 

 fragmental clay-slates and graywacke-slates whicli are again practically 

 identical in character. It is true that in the western part of the Penokee 

 district mica-schists have developed from these slates, but the original con- 

 dition of these rocks was essentially like that of the unaltered phases. 



Underlying both the Animikie and the Penokee series is a complex of 

 granites and schists, the unconformity between which and these series is of 

 the most pronounced character. That the Animikie series is thiis separated 

 from the underlying rocks has been seen by all who have studied it, and, 

 considering this g-eneral agreement, the proof of this unconformity will not 

 be here repeated. Above both series follow the Keweenaw rocks. In 

 both districts, in passing at any place from the underlying rocks to the 

 Keweenaw series in section, the two are in apparent conformity; but when 



