CAEB0NIFEE0TJS SYSTEM. 



217 



compact limestone, sometimes uniformly bedded, but it often 

 has a concretionary and even a brecciated character. These 

 divisions may be observed to best advantage in the south- 

 eastern corner of Iowa and the adjacent parts of Illinois. 



Mr. Worthen, State Geologist of Illinois, gives in his report 

 the following section of the rocks of this formation at the town 

 of Warsaw, on the east side of the Mississippi river, imme- 

 diately opposite the southeast corner of Iowa. It is repre- 

 sented by hg. 10, and introduced here because it is more com- 

 plete than any afforded by exposures upon the Iowa side : 



Fig. 10. 



No. 4. Concretionary and brecciated limestone 30 feet. 



No. 3. Arenaceous limestone 10 feet. 



No. 2. Blue argillaceous shales and limestone I 30 feet. 



No. 1. Magnesian limestone 12 feet. 



28 



