36 T. E. Savage — Relations of the Alexandrian Series. 



filistriata, S. hanoverenis, Whitfieldella sp., Cyclonema day- 

 tonensis, lllcenus daytonensis, Illmnus cf. madisonianus. 



The above species indicate for this limestone an age nearly 

 equivalent to the Sexton Creek limestone of southern and 

 northeastern Illinois and the Brassfield of Ohio and Kentucky, 

 hut such characteristic Sexton Creek fossils as Rhinopora near 

 verrucosa, Pentamerella f manniensis, Stricklandinia tri- 

 jylesiana, Stricklandinia sp., and Triplecia ortoni were not 

 found in this region. Since a northern sea invasion is known 

 to have occurred during the Sexton Creek (Brassfield) period 

 of deposition, it is thought that this limestone may represent 

 deposition in a northern province during Sexton Creek time. 

 Hence it may be known as the Waucoma limestone, from the 

 village of that name in Fayette County, Iowa, near which it is 

 well exposed. 



The relations of the Alexandrian strata of eastern Missouri 

 and southern and northeastern Illinois to the Silurian lime- 

 stone of Iowa are shown in tabular form below. 



Table showing the relations of the Alexandrian series of Illinois 

 and Jlissowi to the Silurian of Iowa. 





Eastern Mo., and southern 

 and northeastern 111. 



Iowa 



Niagaran 





Gower limestone 



Series 



Hopkinton dolomite 





Sexton Creek limestone 



Waucoma limestone 



Alexandrian 

 Series 



f Bowling Green 

 Edgewoodj limestone member 

 formation j Cyrene limestone 



[_ member 



Winston limestone 





Girardeau limestone 





Summary. 



It has been shown that the unconformity below the Bowl- 

 ing Green limestone member is not general, but is limited to 

 the area in which the oolite phase of the underlying portion 

 of the Edgewood formation is developed. 



The statigraphic relations and the fossil content of the 

 Bowling Green limestone member proves that this limestone 



