282 C. R. KEYES — DEVONIAN INTERVAL IN MISSOURI 



The relations of the Burlington section and the section of the typical 

 Kinderhook (Chemung of the early Missouri geologist) have recently 

 been clearly set forth. * It has been shown that the basal shales of the 

 Burlington section represent much more than the Hannibal shales or 

 median member of the original Kinderhook section. The 150 feet of 

 shales beneath the waterlevel very nearly correspond to the Grassy Creek 

 shales of Missouri, a formation nearly 200 feet in thickness, lying imme- 

 diately below the Louisiana limestone and base of the Kinderhook. 

 Northward, as has been stated, the Louisiana limestone, which is 50 feet 

 thick at the type locality, becomes thinner and thinner and finally fails 

 altogether soon after passing the southern Iowa boundary. This brings 

 together at Burlington the Grassy Creek shales f and the Hannibal 

 shales, thus forming a single great stratigraphic and lithologic sequence. 



The Grassy Creek shales, so far as their faunas are concerned, are 

 undoubtedly Devonian in age. The rich faunas recently found in the 

 so-called Kinderhook shales that are above the waterlevel at Burlington 

 present strong Devonian affinities. J This would indicate rather clearly 

 that faunally the shale section at Burlington is a unit also. Lately 

 Weller, § who is giving special attention to the Kinderhook faunas, has 

 attempted, entirely on faunal grounds, to locate at Burlington the 

 horizon of the base of the Louisiana limestone at the bottom of the fine 

 argillaceous limestone above the Chonopectus sandstone, a level which 

 is only 30 feet below the bottom of the Burlington limestone and at the 

 top of the green shales of this section. 



DUAL NATURE OF ORIGINAL KINDERHOOK FAUNA 



Ten years ago the writer visited along the Mississippi river all the 

 type localities of the formations belonging to the Lower Carboniferous, 

 or Mississippian series. It was for the express purpose of obtaining at 

 first hand definite data relating to exactly what was referred to in the 

 literature of the subject. Without attempt to revise the classification 

 of the series from the foundation up, a summary of that investigation 

 was published || under the title of the " Principal Mississippian Section." 



Among many other things, it was found at that time that the actual 

 faunal characteristics of the original Kinderhook formation were very 

 different from the ideas which had been gathered from a perusal of the 

 literature. The ascribed fauna of the lowermost member of the four-fold 

 Mississippian series was in fact a fancied fauna instead of a real one 



* Journal of Geology, vol. viii, 1900, p. 315. 

 fProe. Iowa Acad. Sci., vol v, 1898, p. 68. 

 JProc. Iowa Acad. Sci., vol. iv, 1897, p. 39. 

 I Trans. St. Louis Acad. Sci., vol. x, 1900, p. 123. 

 || Bull. Geol. Soc. Am., vol. iii, 1892, p. 283. 



