PAPERS BY MEMBERS 



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Birdsville formation. 



Tribune limestone. 



Cypress sandstone. 



Ste. Genevieve 

 limestone 



Ohara limestone. 

 Rosiclare sandstone. 

 Fredonia oolitic limestone. 



subordinate members of the Ste. Genevieve limestone, Fre- 

 donia. Rosiclare. and Ohara. were used for the first time by 

 Ulrich in this report, as were also the names Tribune and 

 Birdsville, the two formations in which the Kaskaskia lime- 

 stone was divided. 



The most notable innovation in Ulrich's classification, 

 is the inclusion of the Ste. Genevieve limestone in the Chester 

 g^roup. Eng-elmann had recognized two Chester beds in 

 Johnson and other southern counties in Illinois, which he 

 believed to be sub-Cypress in position, and to these two sup- 

 posed sub-Cypress beds Ulrich gave the names Rosiclare 

 sandstone and Ohara limestone and included them in his 

 larger Ste. Genevieve limestone. The distinguishing fea- 

 tures of Ulrich's Ste. Genevieve is a lithologic succession, 

 limestone below and above with an intermediate sandstone 

 member, rather than any faunal character. 



The detailed field work of the writer during several sea- 

 sons, upon the Chester formations in the \\'aterloo, Renault, 

 Baldwin and Chester quadrangles, comprising parts of ^Nlon- 

 roe and Randolph counties, has led to some important con- 

 clusions in the interpretation of this upper portion of the 

 Mississippian section, which are not wholly in accord with 

 the classification of Ulrich. The detailed observations by 

 W'orthen and other earlier geologists, were confined mainlv 

 to the sections in the Mississippi River blufifs and although the 

 Chester rocks were recognized at many points in the inter- 

 ior, no serious attempt was ever made to establish exact cor- 

 relations between them and the beds in the blufif sections. 

 A careful study of the Chester beds which are widely ex- 

 posed in the stream valleys back from the Mississippi River 

 blufYs, has greatly magnified the importance of the lower 

 members of the section. \\'orthen's lower limestone, bed No. 



