442 T. E. Savage — Stratigraphy of Southwestern Illinois. 



Correla- 

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Descriptions of horizons 



6a. Bed of light colored chert layers, in places alter- 

 nating with impure siliceous limestone, and 

 at other points composed wholly of chert 

 bands. Fossils most abundant in the upper 

 part. Amphigenia curta, Anoplotheca flabel- 

 lites, Eatonia peculiaris, Eodevonaria rnelon- 

 ica, Chonostrophia reversa, Schuehertella 

 pandora, Spirifer worthendnus, and S 1 . hemi- 



cyclus common in the upper part 225 ft. 



In the southern part of Union county the 

 lower cherj layers are massive and contain 

 but few fossils. In the pit worked by the M. 

 and O. railroad, 1 1/2 miles north of Tamms, 

 in Alexander county, may be seen an exposure 

 of more than 100 feet in which few fossils 

 were found. 



A short break in sedimentation. 



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56. Heavy bedded, light colored, coarsely crystalline 

 limestone with Eatonia singularis, Spirifer 

 macropleura, S. perlamellosus, Stropheodonta 

 beckii and Strophonella punctidifera about 58 ft. 



Bed of impure, shaly limestone with bands and 

 nodules of chert in the upper portion. Dal- 

 manella subcarinata, Meristella la>vis, Spirifer 

 cy&lopterus, S. perlamellosus and Strophonella 



punctidifera . . about 100 ft. 



The horizon of 5a appears to belong immedi- 

 ately below 56. It is doubtless present at Bald 

 Eock and in the river bluff further south, but 

 the fossils were not found at the latter points. 



A long break in sedimentation. 



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4c. Pink, mottled limestone in layei's 10-45 inches 

 thick, containing many small, immature bra- 

 chiopods, with which occur Plectambonites 

 transversalis, Rafinesquina mesacosta and 

 Spirifer near sulcata 23 ft. 



46. Layers of gray to drab colored limestone, 2-6 

 inches thick, alternating with thin bands of 

 chert, and characterized by such typical Clin- 

 ton fossils as Stricklandinia triplesiana, and 

 Triplecia ortoni 6 ft. 



4a. Bed of tough, gray limestone in layers 3-8 inches 

 thick, which are imperfectly separated by 2- 



to 4-inch partings of chert. Fossils rare 0-46 ft . 



4a is wanting at some points in this area. 



