76 



GEOLOGICAL FORMATIONS. 



by a clear description of this formation. Kaskaskia necessa- 

 rily must be retained, therefore, for the upper member of the 

 Mississippian series in preference to "Chester." If it is desir- 

 able to keep the latter term in geological nomenclature, it 

 might be advisable to restrict it to the upper shaly division, 

 which can be advantageously distinguished from the lower 

 massive limestones, and "Chester shales," as they are now often 

 called locally, could still be made a useful term. 



The Lower Carboniferous and its Subdivisions. 



From the foregoing considerations of the different mem- 

 bers of the Lower Carboniferous, or Mississippian, it is to be in- 

 ferred that upon the best lithological, stratigraphical and fannal 

 evidence now at hand, the series embraces four groups. These^ 

 and the various subdivisions that have been recognized from 

 time to time, are tabulated below : 





Kaskaskia . 



"Chester ehales." 

 "Kaskaskia limestone." 

 Aux Vases sandstone. 



MISSISSIPPIAN 



SERIES. 



Saint Louis. 



Ste. Genevieve limestone. 



Saint Lonis limpstone 



Warsaw limestone fin part not typical) . 



Augusta. 



Warsaw shales and limestone (typical) . 



"Geode "led " 



Keokuk limestone. 



Upper Burlington limestone. 



Lower Burlington limestone. 





Kindeihook. 



Chouteau llmoistone. 

 Hannibal shales. 

 Louisiana limestone. 



The names given in quotation marks are local applications. 

 The Kaskaskia, aside from the basal sandstone, appears to be 

 a well-defined, two -fold division, and it seems advisable to keep 

 the two members distinct, though special names are not retained 

 for them here. The Saint-Louis and Kaskaskia correspond es- 

 sentially to Williams' "Ste. Genevieve group." 



The "Louisiana limestone" is layer number 6 of the Louisi- 

 ana exposures. The " Hannibal shales " comprise numbers 7 

 and 8 of the same locality; probably, also numbers 1 and 2 of 



