272 C. R. KEYICS — DEVONIAN INTERVAL IN MISSOURI 



From northeastern Iowa southward the main member of the Devo- 

 nian — the Cedar Valley limestone — maintains its full development and 

 characteristics to the southeastern part of the state. It is an easily rec- 

 ognizable stratum in deep-well sections to beyond the state boundaries. 



The basal member, called the Independence shales by Calvin,* is 

 comparatively limited in its geographic extent. 



The uppermost shale member appears to have a rather remarkable 

 distribution and development. Should recent correlations be correct, 

 one problem will have been solved that has completely baffled investi. 

 gators from the earliest inquiries in this region, more than 50 years ago- 



The Sweetland beds of Muscatine county f appear to be the strati- 

 graphical equivalents of the Lime Creek shales. They are also to all 

 appearances the basal part of the so-called Kinderhook shales at Bur- 

 lington, but their stratigraphic level is probably 100 feet beneath low 

 water at that place, 60 feet only of the shale formation being above the 

 river. 



The nominal history of these beds is full of interest. From the time 

 when Hall X first brought these beds into notice the conclusions drawn 

 by this author seem to have been misunderstood. To this point atten- 

 tion will be directed later. 



NORTH MISSOURI BEDS 



Between the Silurian limestones and the Burlington limestone there is, 

 in northern Missouri, a succession of beds the geological age of which 

 has long been a subject .of controversy. The section § here referred to 

 the Interval may be thus expressed : 



General North Missouri Succession 



Feet 



Hannibal shales , 75 



Louisiana limestone 50 



Grassy Creek shales 30 



Callaway limestone 30 



Of the terranes mentioned, the Callaway limestone is believed to be 

 the southern extension of the great Cedar Valley limestone of Iowa. 

 While rich in fossils, its fauna has never been described. Only a few 

 species have been noted as coming from it, and these have never been 

 figured. 



The Louisiana limestone has been clearly shown || to be a rather lim- 



*Bull. U. S. Geol. and Geog. Survey Terr., vol. iv, 1878, p. 725. 



tlowa Geol. Survey, vol. ix, 1899, p. 289. 



X Geology of Iowa, vol. i, 185S, p. 88. 



§ Proc. Iowa Acad. Sci., vol. v, 1898, p. 59. 



|| Journal of Geology, vol. viii, 1900, p. 317. 



