298 



('. R. KEYES — THE PRINCIPAL MISSISSJPPIAN SECTION. 



hat stream, have been land surface-; and were greatly eroded before the 

 invasion of the coal swamps. In many places throughout the same 

 region the coal strata rest on older rocks, on other members of the Mis- 

 sissippian series, and even on the Devonian. 



Further consideration of the series is unnecessary here. In one por- 

 tion of the area under consideration the Coal Measures have been studied 

 with considerable care and a very detailed section made from near the 

 ancient land limit seaward a distance of nearly 75 miles. A preliminary 

 statement of these observations lias been made elsewhere* 



Recapitulation. 



From the foregoing description it is to be inferred that, on the best 

 lithological, stratigraphical and faunal evidence now at band, the Mis- 

 sissippian series embraces tour groups, which may be tabulated as fol- 

 lows : 



Kaskaskia group 



St. bonis group 



Mississippian series 



( >sage group 



f " Chester shales." f 



" Kaskaskia limestone.' 1 

 ( Aux Vases sandstone. 



("Ste. Genevieve limestone.' 1 

 ! St. Louis limestone. 

 Warsaw limestone (in part ; 

 not typical). 



[ Warsaw shales and limestone 

 (typical). 

 " Geode bed." 

 K eokuk lim estone. 

 Upper Burlington limestone. 

 Lower Burlington limestone. 



f Chouteau limestone. 

 Kindcrhook group -. Hannibal shales. 



( Louisiana limestone. 



The " Louisiana limestone ,! is layer number 6 of the Louisiana ex- 

 posures. The "Hannibal shales 1 ' comprise numbers 7 and 8 of the 

 same locality; probably also numbers 1 and 2 of the Burlington section. 

 The " Chouteau "' is number 9 of the Louisiana limestones. The "lower 

 Burlington limestone" embraces numbers 7 and 8 of the Burlington 

 section; the "upper Burlington limestone 11 numbers 9 and 10 of the 



* Bull. Geol. Soc. Am., vol 2, 1890, pp. 277-292, plates ix, x. 



f The names in quotation marks arc local applications. The Kaskaskia, aside from the basal 

 sandstone, appears to be a well defined two-fold division, and ii seems advisable to keep the two 

 members distinct, though special names are not retained for them here. The Si Louis and Kas- 

 kaskia correspond essentially to Williams' "Ste Genevieve group." 



