"2S4 C. R. KEYES THE PRINCIPAL MISSISSIPPIAN SECTION. 



Especially was this the case along the line of the Mississippi river, when' 

 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'.- views underwent considerable change during 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 always has 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 locali- 

 ties situated on the " Father of Waters." The Mississippi section, there- 

 fore, becomes the most important of all in the correlation of the lower 

 Carboniferous rocks of the great interior basin. Fortius reason it was 

 that recently all the original localities were visited, the various exposures 

 examined in detail, their relationships with each other and with the over- 

 lying and underlying strata particularly noted. 



The nominal history of the major subdivisions of the Paleozoic of the 

 Mississippi basin need not be reviewed in this place. Suffice it to men- 

 tion that the term Subcarboniferous had in the beginninga very different 

 meaning from what it has had of late years. As originally proposed by 

 Owen * the name was used merely to indicate an indefinite series of limc- 

 -t.iues below the coal-bearing strata of the interior. Subsequently f the 

 same author limited the formation below to the blue, fossil-bearing lime- 

 stones now known as the Cincinnati beds. In was in 1847, when Owen 

 and Norwood J gave the "black slates'' as the upper limiting member of 

 the Devonian, that " Subcarboniferous" was still farther restricted, thus 

 for the first time giving the name Subcarboniferous the meaning which 

 has been generally attached to it of late years. 



The most familiar name- assigned to the subdivisions of the Carbon- 

 iferous along the Mississippi river are ten in number, viz: Chouteau, 

 Kinderhook, Burlington, Keokuk. Warsaw, St. Louis. Ste. Genevieve, 

 Chester, Kaskaskia, Coal Measures. 



Typical Sectioxs along the Mississippi Rivep. 



A few of the most characteristic sections have been selected for notice 

 here, and their lithological details are briefly explained. By comparison 

 with the general section (plate 9) it is thought that the stratigraphical 



* Rept. Geol. Rec. Indiana, is:;: 1 1839), p. 1^. 



t Rep. nu .Min. Lands of the United States, 1840, p. 14. 



f Researches "n the Protozoic and Carb. Rocks of ci ntral Kentucky during the year 1846 (1847) 



