JOURNAL OF PROCEEDINGS. 189 



fully examined, I will confine myself to a few remarks on the Lower Car- 

 bonifei ous. 



This for mation has bpen studied thoroughly in its development near the 

 Mississippi River — in Central Illinois, Iowa, and Missouri. Underlying 

 the Coal Measures, theie have been distinguished 



1. The Ferruginous Sandstone, 



2. The St. Louis Limestone, 



3. The Warsaw Limestone, 



4. The Keokuk Limestone, 



5. The Encnnital or Burlington Limestone. 



Farther south, the Kaskaskia or Chester Limestone was found intercala- 

 ted between the Coal Measures and the Ferruginous Sandstone ; and then 

 heavy masses of sandstone (the Millstonegritj were observed next below 

 the Coal Measures, and also beds of sandstone intercalated with the Ches- 

 ter Limestone. 



My observations now show that in theex'reme southern part of Illinois 

 this upper division of the Lower Carboniferous attains a still gre iter and 

 more varied development, while the lower subdivisions observed farther 

 north appear to be lost or ine.ged into one. I distinguish these : 



A. Coal Measures. 



B. Millstone-grit: purely quartzose, rather finely-grained, rarely con- 

 glomeratic sandstones, with some shaly intercalations. It reaches a thick- 

 ness of about 500 feet, and includes, f.ir above the middle, a sean, of coal 

 which has been found continuous along the outcrops of the formation 

 through several counties, dividing it into Upper and Lower Millstonegrit. 



C. Then follows a series of strata which coirespond to the Chester 

 Limestone and Ferruginous Sandstone, an<! which, as I have stated, forms 

 the most prominent poition of the Lower Carboniferous formation of this 

 distrrct. It consists chiefly of alternations of siliceous Archimedes and 

 Peutiemital limestones, of shales, and sandstones; and where it is most 

 fully developed, in Johnson and adjoining counties, reaches an aggregate 

 thickness of about 1,000 feet. There it presents 



1. Limestones, generally highly siliceous and even flinty, and shales, with 



an aggregate thicki.ess of about 180 feet. 



2. Quartzose sandstones, alernating with shaly beds, and in some places 



slaty limestone at its upper part, from 120 to 150 feet. 



3. Limestones and shale=, fiom 80 to 120 feet. 



4. Quartzose sandstones with some beds of shale, over 100 feet. 



5. Siliceous limestones and shale, in places as much as 140 feet. 



6. Quartzose sandstones and shales, fiom 60 to 100 feet or more. 



7. Siiici-ous limestones and shales, about 150 feet. 



8. Quartzose sandstones with some shaly portions, about 150 feet thick. 



I have distinguished them by the name of Cypress Sandstones on ac- 

 count of their prominent development on Cypress Creek. 



9. Siliceous limestones and shales, the latter in places arenaceous. These 



appear as beds of passage between C and D, while at many points 

 No. 8 rests directly on I). 



10. Locally, strata of sandstone intervene between No. 9 and D; they 

 generally appear as an unimportant bed of transition, neither thick 

 nor pure, but rather as an arenaceous development of the shales of 

 No. 9. 



The limestones of the formation C are usually highly siliceous, hard, 

 and partly magnesian, of a grayish color, and vary between the closest 

 texture and coarse crystalline. Some contain seams of flint, especially 

 No. 1. Th»-y all contain fossils, described before from the Chester beds; 

 but I have also found strata with a curious mixture of fossils of the lower 

 formation, the position of which in The series could not be ascertained, 

 and which may possibly belong to D. Some strata, which I believe to be 

 the equivalents of No. 9, contain Oolitic portions, a feature else distin- 

 guishing D. 



