410 



INDEX TO THE STEATIGEAPHY OF NORTH AMERICA. 



Comparing the classification of the formations of the Appalachian Basin (east 

 of the Cincinnati arch) — that is, those of the Waverly group — with the divisions 

 of the typical Mississippian, Weller accepts Stevenson's conclusion" that only the 

 upper part of the Pocono is of Mississippian age and that this upper part is strati- 

 graphically continuous with the Waverly. "The most definite point of faunal 

 contact between this basin and the Mississippi Valley basin is foxmd in the Maxville 

 limestone, whose fauna is to be correlated essentially with the Ste. Genevieve of 

 southern Illinois and Missouri." 



• The Iowa section of the Mississippian as compiled by Chamberlin and Salis- 

 bury ^^^^ from the reports of the Iowa State Survey is as follows: 



Mississippian formations in Iowa. 



In northern and central Iowa, owing to the effects of elevation . and erosion 

 during the later part of the Mississippian epoch, the higher divisions of the series 

 are unrepresented; they are restricted to the southern portion of the State and 

 the Kinderhook alone extends across it.^°^ 



On each side of Mississippi River between Burlington, Iowa, and southern 

 Illinois occur the typical sections of the Mississippian. The deposits are chiefly 

 limestone, but in both the lower and the upper portions occur shales and sand- 

 stones, which mark the advance and retreat of the Mississippian sea. The basal 

 formations (Kinderhook group) are irregular in occurrence, varying lithologicaUy 

 and faunally, and there are unconformities by erosion, particularly at the base of 

 theKaskaskia.*'''^^^'^" 



In southwestern Missouri and northern Arkansas, on the southwestern shore 

 of the Ozark land, the Mississippian formations are, according to Adams and 

 Ulrich,^'' as follows: 



<» ' ' The lower portion of the Pennsylvania Pocono * * * decreased rapidly in the southwestern part of the 

 State [Virginia] until it disappeared or was merged into the Grainger [Devonian] shales of M. R. Campbell." Steven- 

 son, J. J., The Lower Carboniferous of the Appalachian Basin: Bull. Geol. Soc. America, vol. 14, 1903, p. 35. 



"His [White's] Shenango shales, Shenango sandstone, and Meadville shales, down to and including the upper 

 Meadville limestone, are undoubtedly Lower Cai-boniferous, while the underlying divisions — the lower part of the 

 Meadville shales, the Sharpsville sandstones, the Orangeville shales, and the Oil Lake group — are evidently later 

 Devonian." Idem, p. 40. 



