344 



CHALMER L. COOPER 



r^y^-'^'-yj'^ 



Fig. 1. — Map of the upper part of the Mississippi embayment area showing the outcrop of the Wilcox 

 and Midway groups and the location of the well at Cache, Alexander County, Illinois. 



From geologic maps of Tennessee (1923), Kentucky (1929), Illinois (1939), and Missouri (1939, revised by recent work of 

 the Missouri Geological Survey). 



