GEOLOGICAL INTRODUCTION 13 



Yankeetown formation. 



Renault formation. 



Brewerville sandstone. 

 IV. Ste. Genevieve limestone. 

 III. Meramec group. 



St. Louis limestone. 



Salem limestone. 

 II. Osage group. 



Warsaw formation. 



Keokuk limestone. 



Burlington limestone. 

 I. Kinderhook group. 



Containing many formations more or less local in their 

 geographical distribution. 



I. KINDERHOOK GROUP 



The lowermost formations of Mississippian age, constituting the Kinder- 

 hook group, were correlated by Hall with the Chemung formation of the 

 New York Devonian section, but they are now universally considered to be 

 of younger age, and to constitute the initial group of formations in the 

 Mississippian system. The Kinderhook formations are exceedingly variable 

 in their development in different parts of the Mississippi Basin, including 

 limestone, sandstone, and shale formations. The sections lack uniformity 

 in any two localities separated by a considerable distance ; and the faunas 

 show much variation in the several formations and in different regions. 



At the locality from which the name of the group was derived, Kinder- 

 hook, Pike County, Illinois, the following section may be seen : 



SECTION AT KINDERHOOK, ILLINOIS 



Osage group. 



4. 'Burlington limestone. 



Kinderhook group. Feet 



3. Thin-bedded, fine-grained limestone. 6 



2. Thin-bedded sandstone and sandy shales 36 



1. Argillaceous and sandy shales, partly hidden 40 



Another locality considered as typical by Meek and Worthen, who first 

 used the name Kinderhook group, is that exposed in the neighborhood of 

 Burlington, Iowa, where the following succession of beds may be studied : 



SECTION AT BURLINGTON, IOWA 



Osage group. 



8. Burlington limestone. 



Kinderhook group. Feet 



7. Soft, buff, dolomitic limestone .' 3-5 



6. White, oolitic limestone 2-4 



5. Fine-grained, yellow sandstone 6-7 



