A DEVONIAN OUTLIER OF THE OZARK UPLIFT 457 



CORRELATION 



From the foregoing table it is evident that this fauna is of 

 Onondaga age, and that it is the partial equivalent of the Grand 

 Tower formation of southern IlUnois and southeastern Missouri. 

 Its affinities are entirely with the eastern Devonian and have 

 no resemblance to the later Devonian faunas of Iowa and north 

 central Missouri. Of the thirty-seven identified forms, seventeen 

 occur in the Grand Tower formation of southern Illinois, thirty 

 in the Jeffersonville beds of southern Indiana, thirteen in the Onon- 

 daga group of Michigan, twenty-two in the Onondaga of Ohio and 

 eighteen in the Onondaga of New York. These figures are not 

 exact and are probably too low, for the faunal fists from the various 

 regions are incomplete and represent compilations in most cases. 

 The most complete lists are those from the Grand Tower formation 

 and from the Jeffersonville beds. Weller^ and Savage^ have shown 

 the relationship of the Grand Tower fauna to the Onondaga of the 

 eastern United States. 



Savage^ has also shown that the Jeffersonville beds are the 

 equivalent of the upper portion of the Grand Tower of lUinois. 

 Since more than 80 per cent of the forms occurring at Rolla are 

 also found in the Jeffersonville beds, it seems certain that this 

 outfier belongs to the upper portion of the Grand Tower formation. 

 In Ste. Genevieve County, Missouri, Weller'' assigns over two 

 hundred feet of strata to the Grand Tower formation. Certain 

 horizons in this formation are reported to be full of corals, but 

 until the faunal lists for this formation are completed, a closer 

 correlation cannot be made. 



CONCLUSIONS 



The presence of a Grand Tower outfier at Rolla indicates a 

 much greater submergence of the Ozark upfift during Onondaga 

 time than has commonly been supposed. The nearest outcrops of 

 the Grand Tower formation are at least 100 miles to the east. The 



I S. Weller, loc. cit. 



^ T. E. Savage, loc. cit. 3 Ibid. 



4 Stuart Weller, unpublished manuscript on Ste. Genevieve County, Missouri, 

 Missouri Bureau of Geology and Mines. 



