williams.1 CONCLUSIONS. 265 



southwestern Missouri and northern Arkansas, in distinguishing in 

 some cases whether a fauna is a Warsaw or a St. Louis fauna. The Cues- 

 ter fauna may be associated with particular conditions of environment. 



On considering these several facts, it has appeared to the writer that 

 in classifying the formations of the Mississippian series the correlations 

 from a structural point of view have been carried too far and that an in- 

 crease in the number of litholog»ic formations will better express the 

 facts as at present known ; whereas from a paleontologic point of view 

 the classification is too minute, and that a combination of some of the 

 formations will best express our present knowledge regarding their true 

 relations. The practical application of this suggestion will result in 

 applying new local names to structural formations whenever the struc- 

 tural characters are so divergent from those of the typical section that 

 the correlation depends upon stratigraphio position above or below 

 some clearly recognized horizon for its validity. 



Recent studies of the fossils, their original grouping into local faunas 

 and their association in other parts of the province, have led me to rec- 

 ognize three fairly well differentiated faunas in the Mississippian series, 

 the subdivisions of which are believed to be local, and therefore very 

 unsatisfactory for purposes of correlation. 



The following table sets forth the proposed classification and nomen- 

 clature : 



Structure scale. Time scale. 



Chester stage 1 



St. Louis stage , > Genevieve age. 



Warsaw stage J 



Keokuk stage ^ 



Mississippian series . . ; Burlington stage \ Osage age. 



{ Chouteau limestone a 



Kinderhook I Vermicular shale and sand- 

 stage, in-^ ^Chouteau age. 



eluding 8tone 



^Lithographic limestone j 



The Chouteau age is the age of the Chouteau group of Broadhead. 

 The Osage age is the age of the fauna of the Burlington and Keokuk 

 formations, which are locally distinguishable, but in the sectious on 

 the northwestern, western, and southwestern flanks of the Ozark Uplift 

 are so blended that it seems impracticable in most cases to differentiate 

 them. The name is suggested by the fact that the Osage Kiver drains 

 the region in which this confusion of the two faunas is clearly exhib- 

 ited. The Genevieve age is the age of the fauna of the Archimedes 

 group of Shumard. 1 



The name is suggested by the fact that Shumard first called attention 

 to the union of the several formations in which the common fauna pre- 

 vails in his description of the geology of Ste. Genevieve County, Mis- 

 souri. The name he applied was Archimedes group, but this is not a sat- 



1 Eepts. Geol. Survey Missouri, 1855-1871, by G. C. Broadhead, F. B. Meek, and B. F. Shumard 

 Ibid., 1873, pp. 292-293, by B. F. Shumard. 



