ABSTRACTS OP PAPERS 97 



top shale — rests on the black shale of the Chattanooga. Of these three post- 

 Chattanoogan formations the Rldgetop shale is the oldest, the New Providence 

 shale next younger, and the Fort Payne chert the youngest. The last is of 

 the age of the Keokuk limestone of the Mississippi Valley. Locally its basal 

 part may include beds corresponding to late Burlington. The New Providence 

 shale corresponds in age to the Fern Glen formation of Missouri and Arkansas. 

 Weller and others classify the Fern Glen as late Kinderhookian, but the author 

 regards it as Lower Burlington, or at least as post-Kinderhookian ; hence, early 

 Osagian. 



So long as the Chattahoogan was regarded as Devonian, and therefore as 

 distinctly older than the Kinderhookian series, the Ridgetop shale was assumed 

 to be an early Kinderhookian deposit. Fossil evidence from the concerned 

 beds was both scanty and of undetermined significance. In the past two or 

 three years, however, reasonably good collections of fossils have been made 

 fi'om three zones in the Ridgetop shale. These fossils prove conclusively that 

 the formation, instead of being early Kinderhookian in age, in fact represents 

 fi very late fades of this epoch. 



2. The contact between the Chattanoogan and succeeding formations gen- 

 erally indicates a break in sedimentation, except in those sections in which 

 the Ridgetop shale is developed. In these no evidence of discontinuity has 

 been discovered. As the fossils of the Ridgetop shale indicate a late Kinder- 

 hookian age, this continuity of deposition properly leads to the inference that 

 the underlying black Chattanoogan shale also is, at least in part, of early 

 Mississippian age. 



3. Black shale containing Sporangites, and evidently of Chattanoogan age, 

 was discovered during the past year by Prof. Stuart Weller in Sainte Gene- 

 vieve County, Missouri. This bed of shale overlies the Glen Park limestone, 

 which, farther north, overlies the Louisiana limestone. Faunally and litholog- 

 ically the Louisiana corresponds best with an upper member of the typical 

 Kinderhook sections at Kinderhook, Illinois, and Burlington, Iowa. This 

 transgressing, presumably upper part of the Chattanoogan, is thus proved to 

 be late Kinderhookian in age. 



4. South and west of Irvine, Kentucky, the Chattanooga shale is an indi- 

 visible stratigraphic unit. The upper part of this unit Is generally concedetl 

 to be of Mississippian (Sunbury) age. We now learn that the top of the 

 lormation c-orresponds in position approximately to the top of the Kinderhook. 

 and is therefore much younger than the base of the Mississippian in the 

 Mississippi Valley. In seeking to fix the latter boundary in Kentucky and 

 Tennessee, we may follow the principle of drawing the line at the first impor- 

 tant break in sedimentation beneath the part of known late Kinderhookian 

 age. Accordingly, and in the absence of competent evidence of contrary sig- 

 nificance, the l)ase of the Mi.ssissippian in these States should be drawn at the 

 base of the CliMltaiKiogiin. Tliat tliis principle is properly api)licaiiie in this 

 case is intlicated by botli stratigraphic and fauna! evidence. 



5. The strongest and most widely recognizable physical break between un- 

 doubted Devonian and equally well accredited Mississippian deposits In Ohio, 

 Indiami. Illinois, Iowa. Missouri, Ariv.insas. ni<l:ihonin, Kentucky, Tcnnes.see, 

 and Alabiini.i occurs at tiie li:ise of tiic CliattMnoogjin or KiM4l<'rhool<i;iii series. 

 Conunonly the base of this series is marked by a sandy conglomerate; and, 



