246 ILLINOIS STATE ACADEMY OP SCIENCE 



northwest Illinois, and adjacent portions of Minnesota 

 and Wisconsin. During npper Maquoketa time this sea 

 was joined by the transgression toward the northwest 

 of the Fernvale sea from the sonth during lower Waynes- 

 ville time. 



Foerste 1 has shown that the oldest Richmond deposits 

 in the Ontario and Quebec region are of upper Waynes- 

 ville age, and contain, among others, such species as 

 Stromatocerium huronense, Tetradium huronense, Col- 

 umnaria alveolata, Calapoecia huronensis, Catazyga 

 headi, Strophomena sulcata, and Zygospira kentuckien- 

 sis. It is very significant that not one of these species 

 occurs in the Fernvale or Maquoketa of Illinois, Iowa, 

 Minnesota, or Wisconsin. It is thought that the great 

 transgression of the sea in Waynesville time, in which 

 the Fernvale sediments were deposited in the Mississippi 

 valley basin, was from the south, and that it occurred 

 before the oldest Richmond fauna of the Ontario-Quebec 

 region had reached the Ohio-Indiana area. 



CONCLUSION" 



The fauna of the uppermost calcareous strata of the 

 Richmond in northeast -Illinois, and of the Maquoketa 

 in northwest Illinois, Iowa, Minnesota, and Wisconsin in- 

 dicates that these strata are of Waynesville age. They 

 also show that the Fernvale limestone of northeastern 

 and southern Illinois is of practically the same age as 

 the Waynesville. This Fernvale-Upper Maquoketa sea 

 is thought to have advanced from the south, since strata 

 of corresponding age are known to the south in Monroe 

 and Alexander counties in Illinois, and in southern Ten- 

 nessee, and they are not known in the northern part of 

 the continent. 



During early Richmond (pre-Waynesville) time, it is 

 thought that a sea advanced from the northwest into the 

 upper Mississippi valley, in which were laid down the 

 sediments comprising the lower and middle Maquoketa 

 strata of Iowa, Minnesota, northwest Illinois and Wis- 

 consin. During lower or middle Waynesville time, a 

 southern sea invaded the Mississippi valley and Ohio 



1 Foerste, Aug. F., Upper Ordovician formations in Ontario and Quebec. 

 Geol. Surv. of Canada, Memoir 83, 1916. 



