44 GEOLOaiCAL FORMATIONS 



For this lower calcareous portion the term " Subcarbon- 

 iferous" has been applied usually ; but, as will be seen here- 

 after, there are serious objections to the use of this name. 

 " Mississippian series" has heretofore been employed as a 

 substitute in the present connection. The name was orig- 

 inally suggested, in nearly this sense, by Alexander Winchell, 

 and has been recently somewhat modified and applied by H. S. 

 Williams.* 



More than half a century has passed since the rich and 

 varied faunas of the later Paleozoic rocks of the continental 

 interior first began to attract attention. From the beginning, 

 an exceedingly active and ever-growing interest was taken in 

 the various forms of ancient life represented, and as a matter 

 of consequence the geological history of the region was ap- 

 proached from the biological rather than the stratigraphical 

 side. Especially was this the case along the line of the Mis- 

 sissippi river, where the most important exposures of the strata 

 in question occur. 



The relations of the most important horizons of the lower 

 Carboniferous in the upper Mississippi valley were early made 

 out by Owen and others; and although Owen's views under- 

 went radical modifications daring the dozen years that he was 

 engaged in studying these rocks, his subdivisions have been 

 practically the basis of all subsequent classifications. In the 

 main they have been adopted everywhere, notwithstanding the 

 fact that a considerable diversity of opinion has always existed 

 in respect to the minor stratigraphical details. 



In the naming of the several assemblages of beds, the 

 leading and most widely known terms that have been applied 

 have been taken from localities situated on the " Father of 

 Waters." The Mississippi section therefore becomes the most 

 important of all in the correlation of the Lower Carboniferous 

 rocks of the great interior basin. For this reason it was that 

 recently all the original localities were visited, the various expo- 

 sures examined in detail, and their relationships with each other 

 and with the overlying and underlying strata particularly noted. 



*Bul. U. S. Geol. Sar., No. 80, p. 135. 1891. 



