CHAPTER VIII. 



THE WAVERLY PROBLEM : THE HISTORY OF THE DISCUSSION 

 CONCERNING THE CORRELATION OF THE WAVERLY, MAR- 

 SHALL, GONIATITE LIMESTONE, KINDERHOOK AND CHOUTEAU 

 FORMATIONS. 



In the second stage of development in the history of geologic correla- 

 tions, American geologists did not rely solely upon fossils, but promi- 

 nent stratigraphic units of each new province surveyed were identified, 

 partly by their petrographic, partly by their paleontologic characters 5 

 and local and independent classifications and nomenclatures were con- 

 structed, using these stratigraphic units as datum levels. Thus the 

 Coal Measures, with actual coal beds, formed the most conspicuous 

 datum plane for the correlation of the interior} then the limestones 

 below were correlated with the Carboniferous limestones of England. 

 Going still finer, the Black shales (often called " black slates") assumed 

 a prominent role in determmiug the division line between the Car- 

 boniferous and Devonian. 



The Coal Measure Conglomerates have also played a prominent part 

 in marking the base of the Coal Measures, although in actual age, as 

 represented by the evolutional history of organisms, I am inclined to 

 believe that in different parts of the country the whole length of the 

 Carboniferous limestone period transpired between the times when the 

 lowest Coal Measures of the several regions began, and that, therefore, 

 Conglomerates which mark the elevation preceding such Coal Measures 

 vary greatly in age. The Oriskany sandstone played a similar part in 

 the more eastern sections. The Catskill sandstone, as the supposed 

 equivalent of the Old Red sandstone, formed a conspicuous landmark 

 and division plane between Devonian and Carboniferous in the northern 

 Appalachian province. 



The influence of the belief in the continuity of such stratigraphic 

 units was, and is still, one of the stumbling-blocks in the way of a cor- 

 rect interpretation of the relation between the Waverly formations ot 

 Ohio, and the more eastern strata of New York and Pennsylvania and 

 those of Indiana and the Mississippi province farther west. 



In the more minute application of correlation methods the same in- 

 fluence predominates. In attempting to classify the formations across 

 State boundaries, the prevailing custom has been in the case of each 

 prominent limestone or sandstone to seek the corresponding limestone 



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