22 FLUORSPAR DEPOSITS OF SOUTHERN ILLINOIS, [bull. 255. 



recognizes thive members within the formation. They may he de- 

 scribed as below : 



Generalised section Hte. (Jeiieviere linieistoiie. soiifJiern lUinois. 



Thickness 

 in feet. 



Obara moml)er. Limestone, fine grained, thin bedded, in part slaaly and 



always associated with shale MO-107 



Rosiclare member. Calciferous sandstone ; in weathered exposures 

 showing much sand and usually marked cross-bedding; in un- 

 weathered surfaces predominantly calcareous material and easily 

 overlooked 1-25 



Fredonia member. Mainly oolitic limestones, white and light blue, 

 interbedded with crinoidal, crystalline, and fine-grained limestones 118 



Total 144-245 



While the whole of the formation is fossiliferons, the Ohara mem- 

 ber is particularly so, the shaly bands being- crowded with fossils. 

 One of these bands, occurring usually about 30 feet above the Kosi- 

 clare sandstone and being about 8 feet thick, forms a horizon easily 

 recognized and hence of considerable importance in stratigraphic 

 work. From it at Shetlerville the following fossils, as determined 

 by Mr. Ulrich, were obtained : 



Zaphrentis pelltensis. Cleiothyris sublamellosa. 



Amplexus geniculatus. Cleiothyris hirsuta. 



Pentremites florealis. Seminula trinuclea. 



Spirifer leidyi. Dielasma formosa. 



Spiriferina norwoodi. Dielasma turgidum. 



Spiriferina transversa. 



DistribvtioK. — The Ste. Genevieve limestone is very widely dis- 

 trilnited in both Pope and Hardin counties. It is shown on the 

 accompanying maps (Pis. II and III), both surrounding the St. 

 Louis limestone near Hicks and outcroj^ping between it and the 

 Cypress sandstime in the Rosiclare area. In addition, it occurs both 

 east and north of Cave in Rock, near Shetlerville, Eichorn, and at 

 various other points which will l)e more particularly noted in 

 describing the various mines. Its significance in the present dis- 

 cussion arises from the fact that the important ore bodies so far 

 found have been in most cases closely associated with this limestone. 



Nanie and correlation. — In the work of Engelmann and Worthen 

 the Ste. Genevieve limestone was not discriminated from the St. 

 Louis and the general group to which the name Chester was applied. 

 The Fredonia member seems to have been considered to belong with 

 the St. Louis, while the Rosiclare and Ohara members were sometimes 

 included with the overlying beds and sometimes not." 



These discrepancies came mainly from the fact that faulting was 

 not recognized as important in interpreting the stratigraphy of the 



"See sections, p. 78 and p. 397, (!eoI. Survey lUinois, vol. 1, 1866. 



