r20 



NEW YORK STATE MUSEUM 



II Algonkian time 



catalogue accompanjing it was found to be incorrect, in that it 

 represented the basal qnartzite as Ijing above some of the younger 

 rocks. It became necessary, therefore, to arrange the specimens in 

 their proper relationship according to the published reports on the 

 geology of the region. The following arrangement was adopted 

 for labeling. 



SYNOPSIS 



III Paleozoic time Cambrian system 



2 Keweenawan system 

 1 Huronian system 



(Penokee and Marquette 

 formations are synchronous) 

 I Archean time Rocks of the basement com- 

 plex 

 Rocks of the basement complex 



' (Dike rocks) 

 Syenite 

 Granite 

 Mona schist 

 Kitchi schist 

 Peridotite 

 (Dike rocks) 

 Palmer gneiss 

 Southern complex | Micaceous schist 



Hornblende schist 

 I Granite 



Rocks of the Penokee iron-bearing district of Michigan and 

 Wisconsin 



Northern complex 



a 



O 

 60 



2 Keweenawan system 



1 Huronian system ........ | 



Upper slate member 

 Iron-bearing member 

 Quartz slate member 

 Cherty limestone 



Roeks of the Marquette iron-bearing district of Michigan 





§ )■ Cambrian system 



