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tion 26, Jonesboro township (T. 12 S., R. 2 W.) in Union 

 county. The section is designated S. 60, and the sequence is 

 from the bottom upward. 



S 60 a. Bed of gray to yellow chert in layers four to nine inches 

 thick ( Clear Creek formation ) 9 feet. 



S 60 b. Reddish-brown, rather friable sandstone (Grand Tower 

 formation) 2 feet. 



S 60 c. Gray chert in layers three to eight inches thick, containing 

 numerous Clear Creek fossils 1 foot, 6 in. 



S 60 d. Reddish-brown, friable sandstone, in layers ten to eighteen 

 inches thick (Grand Tower formation) 2 feet, 10 inches 



Michelinia stylopora a, Pentanfenella cf. arata r, 



Aniphigenia curta r, Spirifer duodenarius r, 



Meristella cf. lentiformis r, Spirifer cf. granulosus c. 



S 60 e. Layers of gray chert, three to nine inches thick, containing 



numerous fossils characteristic of the Clear Creek formation 



5 feet, 7 inches 



S 60 f. Reddish-brown, rather soft sandstone, containing many 

 fossils 6 feet, 8 inches 



Faz'osites h)cmisphericiis? c, Aniphigenia curta r, 



Michelinia stylopora a, Leptostrophia perplana r, 



Zaphrentis e.vigua c, Meristella cf. lentiformis r, 



Zaphrentis cf. nitida c, Nucleospira cf. elegans r, 



Zaphrentis cf. recta c, Spirifer sp. c, 



Zaphrentis ungula c. Tentaculites elongatus r 



The interwedging- of the upper layers of the Clear Creek 

 cherts with the lower layers of the succeeding sandstone of 

 Onondaga age, as shown in the foregoing section, indicates 

 that the Onondaga deposits follow the cherts without any 

 break in sedimentation, and that the Clear Creek formation in 

 Illinois represents deposits of Upper Oriskany time. 



A sandstone ledge, eleven feet in thickness, representing 

 a horizon slightly higher than the preceding, is exposed in 

 the southeast quarter of section 34, T. 11 S., R. 2 W. From 

 this outcrop the following fossils were obtained : 



Aulacophyllum trisulcatum? r, Schuchertella chemungensis arctistriata 



Fa^'osifies sp. undt, r, r, 



Michelinia stylopora c, Spirifer duodenarius c, 



Zaphrentis exigna c, Spirifer sp. c, 



Zaphrentis nitida? c, Spirifer cf. macrothyris r, 



Zaphrenttis recta c, Stropheodonta demissa c, 



Zaphrentis ungula c, Conocardium cuneus var. c, 



Athyris I'ittata r, Odontocephalus arenarius c, 



Centronella glansfagea r, Pluicops cristata c, 



Lrptaena rhomboidalis r, Proetus crassimarginatus c, 



Leptostrophia perplana a, Proetus marginalis c, 



Meristella cf. loxtiformis c, Proetus cf. folliceps c, 



Rhipidomclla cf. musculosa c, Proetus sp. r 



Rhipidomella vanuxemi r, 



