APPENDIX. 



Generalized Section for Iowa — Continued. 



559 



Names of Formations. 



Tihckness 

 in Feet, 



Characteristics. 



Maquoketa shales. 

 Possible unconformity- 



Galena-Trenton lime- 

 stone. 



St. Peters sandstone. 



175 



290 



Drab, gray, and black; calcareous in parts. 



Galena phase, dark buff, granular, highly 

 crystalline dolomite. Upper portions ar- 

 gillaceous. 



Trenton phase, alternating beds of shale 

 and non-magnesian limestone; green, buff, 

 and blue. 



100 



White, brown, yellow, red; coarse and friable. 



Oneota formation (in- 

 cludes Shako pee, 

 New Richmond and 

 Oneota proper). 



300 



Dolomite with some interstratified sandstone. 



OJ2 



St. Croix sandstone. 



1000 



Slightly consolidated, disintegrating rapidly on 

 weathering; includes thin, argillaceous, and 

 calcareous seams, and some greensand. 



o g 1 Sioux quartzite. 



Ph ° I 



Hard, vitreous quartzite grading locally into 

 loose sandstone; color usually red to dark 

 purple, or almost white. 



