STRATIGRAPHIC RELATIONSHIPS 



233 



Lithologic similarity in widely separated areas is a most questionable 

 basis for correlation or time equivalence. 



Maqnoketa shales. 



Galena limestone and shales, 120. 



Black River shales, 70. 

 Stones River limestone, 23. 



Saint Peter sandstone, 75-165. 



Unconformity. 



> 



i 



Shakopee dolomite, 10-65. 







New Richmond sandstone, 20. 





o3 

 T3 



Oneota dolomite, 75-175. 







Jordan sandstone, 75-200. 





l«m a 



r ° 5 



.2 <u 



Unconformity in Saint Croix region. 



"i= 



Saint Lawrence dolomites 



and 



.11 



shales, 30-213. 





6C © 





J 



OS CO 





S 



Franconia sandstone, 100. 



> 



5 



o 



02 



o> 



Dreebach shales, 150. 





sin geologists. 



Norton (Iowa). 



ies of Berkey (Minr 



Potsdam or Hincklev sandstones 



-<« 4) . 



and conglomerates, 0-1,000. 





otsdam of Wiscc 

 asal sandstone o 

 asal Sandstone s 

 and Wisconsin) 





J 



PuMPQ 



Figure 2. — Lower Paleozoic Formations, 



Upper Mississippi Valley region. Relative thickness of members of the series is that 

 of southern Minnesota. 



Besides, in this case, even if the beds could be followed continuously 

 from west to east, a former land barrier seems to have actually separated 



