92 Bulletin 12 220 



Feet. 



1. Burlington limestone 200 



2. Chouteau 100 



3. Vermicular sandstone and shale 65-100 



4. lyithographic limestone (rather local)... 60 



5. Black shale 30-40 



6. Hamilton group 120 



In southern Indiana we have the following section (general- 

 ized): 



Feet. 



Carboniferous limestones 300-400 



Massive to shelly sandstone. 1 50-300 



Argillaceous blue to green shales 50-200 



Black shale loo-i 20 



Hamilton 



The relative position of the Rockford limestone and the Litho- 

 graphic limestone in these two sedlions affords very strong strati- 

 graphic evidence of their equivalence. According to Meek and 

 Worthen not one of the fossils occurring in the Lithographic 

 limestone can be positively identified with Hamilton species with 

 the possible exception of an Orthis, while many of the fossils in 

 it occur in the Chouteau beds. The fossils therefore present no 

 evidence against correlating the Lithographic and the Rockford 

 beds. On the other hand, if the Rockford limestone is the equiv- 

 alent of the Chouteau it seems remarkable that Syringothyris 

 carteri, which is a common species in the Chouteau, should be 



