292 . STUART WELLER 



Creek while Archimedes especially, which is such an abundant 

 form in most of the Chester faunas, is inconspicuous in the Renault 

 in most localities, and in very many collections does not occur at all. 



The basis for correlating the Renault across the entire state of 

 Illinois, from St. Clair County to Hardin County, is not only the 

 position of the formation in the stratigraphic column, but also the 

 uniformity of the fossil faunas which occur in the formation. Every 

 species which has been recognized in the Shetlerville-Renault faunas 

 of the southern counties, with the exception of four which are 

 wholly restricted, so far as known, to the Shetlerville beds of Pope 

 and Hardin counties, are known to be present in the typical Renault 

 of Monroe County, except one form which is known in the Paint 

 Creek. Furthermore, the especial index fossils of the Ste. Gene- 

 vieve limestone have nowhere been found in association with the 

 Renault-Shetlerville fauna. While it is not possible in this place 

 to enter into a discussion of the details of the faunal characters of 

 the horizon, it can be said that most detailed studies of these Lower 

 Chester faunas seem to establish without any doubt the paleon- 

 tological correlation of the Renault horizon across the entire state. 



The sandstone beds of the Renault are commonly less massive 

 than those of the Aux Vases, and they not infrequently contain the 

 fossil trunks of a species of Lepidodendron, while no fossils at all 

 have been observed in the Aux Vases. 



Yankeetown chert' and Bethel sandstone.^ — Succeeding the Re- 

 nault formation in the Monroe-Randolph County area in Illinois, 

 there is a thin, but very peculiar and persistent bed, which has been 

 called the Yankeetown chert. This formation is sihceous through- 

 out, much of it is a true chert, but in many locaKties it is seen to 

 include numerous sand grains and locally it is a quartzite. ^ The 

 bedding of the formation is exceedingly irregular and knotty in 

 many places, but locally at least it is quite even. In many places 

 the rock exhibits a distinct, horizontally banded appearance, the 

 separate bands being slightly different in color and only a small 

 fraction of an inch in width. As ordinarily seen in surface outcrops 



^ Weller, Trans. III. Acad. Sci., Vol. VI (1914), p. 124; also III. State Geol. Surv., 

 Monog. I (1914), p. 25. 



^ Butts, Mississippian Formations of Western Kentucky (1917), P- 63 . 



