222 Reviews — American Geological Surveys, Iowa. 



The following: is Dr. White's table of the formations of Iowa : — 



SYSTEMS. 



GROUPS. 



FORMATIONS. Approximate 



(Affes.) 



{Feriods.) 



{Epochs.) 



thickness 





Post-Tertiart. 



Drift. 



in feet. 







/ Inoceramus beds 



50 



Cretaceous. 



Lower Cretaceous. 



< Woodbury Sandstone and shales 



... 130 







( Nisbnabotany Sandstone 



... 100 







( Upper Coal-measures 



... 200 





/ Coal Measures ... 



•| Middle Coal-measures 



... 200 



Carboniferous. 





( Lower Coal-measures 



' St. Louis Limestone 



... 200 

 75 





» Sub-Carboniferous. 



Keokuk Limestone 



Burlington Limestone 



90 

 ... 190 







, Kinderhook beds 



... 175 



Devonian. 



Hamilton. 



Hamilton sbales and Limestone 



... 200 



Upper Silurian. 



Niagara. 



Niagara Limestone 



... 350 





• Cincinnati. 



Maquoketa shales 



80 



Lower 

 Silurian. 



Trenton 



J Galena Limestone 



{ Trenton Limestone 



... 250 

 ... 200 





( St. Peter's Sandstone 



80 





^Primordial 



1 Lower Magnesian Limestone 



.. 250 







( Potsdam Sandstone 



... 300 



Azoie.. 



Huronian (?) 



Sioux Quartzite ..., ... .„ 



50 



3170 



miNNESOTA 



\ \\> 





/7> 



A/le-apures \ 



IVLrSSiOUP^L 



Sketch Map op State of Iowa. 



The first part of the report relates to Physical Geography and 

 Surface Geology. The State has an area of 55,044 square miles. 

 The surface is rolling, but is essentially part of a great plain, con- 



