290 C. R. KEYES — DEVONIAN INTERVAL IN MISSOURI 



relating to the range of the various faunal elements. As already stated, 

 this misunderstanding has been particularly noteworthy in the case of 

 the original Kinderhook. The faunal relations of the several parts of 

 this rock sequence have been fancied rather than real. The actual dis- 

 tribution of the fossils has anomalies and peculiarities that were wholly 

 unlooked for. 



As in the case of the great Ozark series, the original Kinderhook cer- 

 tainly belongs partly to one great system and partly to another. The 

 term Kinderhook can not be modified so as to be made to apply to either 

 part. As a formational name, it is best dropped altogether, except in 

 historical reference. 



The Chouteau fauna of Williams is not the fauna of the original 

 Kinderhook beds. It is essentially the fauna of the original Chouteau 

 limestone, notwithstanding the assertions of its greater extent. As such, 

 it is a valuable unit of both the faunal and rock scales in the taxonomy 

 of Mississippian stratigraphy. 



The original Kinderhook formation of Meek and Worthen is not a geo- 

 logical unit, compact, definitely defined, and geologically useful ; but a 

 medley, unreal, and non-correlative. 



Evidences of Unconformities 



A decade ago* it was suggested that the evidence acquired during the 

 prosecution of the Missouri geological survey indicated that the Carbon- 

 iferous rested unconformably upon the Devonian of the region. While 

 it is not germane to the present theme, it may be stated that many ad- 

 ditional data bearing upon this point have been, of late, obtained. The 

 original Chouteau limestone appears to be the lowest member which was 

 generally regarded as belonging to the Carboniferous that displays un- 

 conformable relationships with the strata underlying. 



Attention has been called to the fact that west of Clinton, in west-cen- 

 tral Missouri, the Chouteau limestone rests on Ordovician rocks ; that 

 eastward from the type locality of this limestone it rests on Devonian 

 shales carrying such forms asAtrypa reclicularis, Or this impressa, etcetera. 

 Thus, in this region, as shown by Marbut,| the shales which are equiva- 

 lent to those below the Chouteau limestone in northeast Missouri, all the 

 Devonian, and the Silurian (" Niagara "), are wanting. 



To the south, in southwestern Missouri, Devonian strata again appear. 

 In northern Arkansas, Williams has lately demonstrated that both the 

 Devonian and Silurian beds are present. On the east side of the Ozark 



* American Geologist, vol. x, p. 384, 1892. 



t Missouri Geol. Survey, vol. xii, pt. ii, p. 121, 1898. 



