170 



THE DEVONIAN AND CARBONIFEROUS. 



| BULL. 8d. 



The classification he proposed is slightly different from that given in 

 Mr. Wortheu's first report of the Geological Survey of Illinois (1866). 1 

 It is as follows: 



f Upper coal. 

 I 



Carbon i f er-< 

 oils system. 



Upper Carboniferous or CoaW T , " 



vj. j Lower coal. 



I Clear Creek sandstone and lower coal. 



Chester group .. \ Chester limestone and Fer- 

 c ruginous sandstone. 

 St. Louis limestone and 

 Warsaw limestone. 

 ( Encrinital and Burlington 

 c group. 

 ( Chouteau limestone. 



Vermicular sandstone and 

 Chouteau group A fihale 



^Lithographic limestone. 



( Hamilton. 

 « Onondaga. 

 Upper Silurian Oriskany. 



St. Louis group. < 

 Lower Carboniferous { Ke » kuk g^P 



Devonian system 



In the use of Chester, St. Louis, and Keokuk groups he follows 

 Worthen (1866). 



He proposes the name u Chouteau group w to take the place of the 

 u Chemung group " of Swallow's Eeport of 1855, 2 which included — 



1. Chouteau limestone, 100 feet. 



2. Vermicular sandstone and shale, 75 feet. 



3. Lithographic limestone, 55 feet. 



" The Chouteau limestone," he reported, " in the upper part is a 

 coarse gray limestone resembling the lower beds of the Encrinital lime- 

 stone In fact it is a bed of passage, as it often contains fossils com- 

 mon to both." " At the base of the group in northeast Missouri a few 

 feet of black slate are occasionally seen. 7 ' The volume adds very little 

 to the development of the correlations of this region. The " Chouteau 

 group " is a very appropriate addition to the nomenclature. The classi- 

 fication of these formations as a group had been early recognized, but 

 the erroneous correlation fixed upon it a name which no one had here- 

 tofore replaced. The " Kinderhook group n of Meek and Worthen is 

 synonymous from a stratigraphic point of view, but the fauna and lithol- 

 ogy of the Chouteau group on the western margin of the Ozark uplift 

 present sufficient differences to make the retention of the name desir- 

 able. 



As we conclude this review of the development of the correlation and 

 classification of the Mississippian series, the problems appear simple, 

 but they were complex and confusing to those who elaborated them. 



1 Report of the Geological Survey of the State of Missouri, including field-work of 1873-'74, with 

 91 illustrations and an atlas, by Garland C. Broadhead, State Geologist. Printed by the authority and 

 under the direction of the Bureau of Geology and Mines. Jefferson City, 1874, pp. 20, 24 



3 Ibid., p. 26. 



