

f-l: 



358 



■T 



On the Silurian Basi7i of 'Mi^U Tennessee. 



If so, the Devonian division thickens towards the southwest- 

 The thinning out of the strata and the commingling of the fos- 

 sils render it difScult to make the separation. 



The following is an approximate section of the rocks, along 

 the Tennessee, commencing with the lowest. 



First, a stratum of impure blue limestone, thin-bedded and 

 fine-grained, of unknown thickness, forty or fifty feet of which 

 are exposed in the blulTs and beds of several creeks in Hardin 

 county. It is a good hydraulic limestone and is beautifully lam- 

 inated in smooth layers, which are from one to 6ve inches thick. 

 It has afforded me, as yet, no fossils, anti hence its age is uncertain. 



Then follow from 100 to 130 feet of limestone, mostly light- 

 gray and thick-bedded, containing crinoidal beds; some of the 

 lower strata with bright green points; middle strata banded by 

 reddish layers which are, generally, fine-grained, impure, cherty 

 limestone, common on the Glades; upper portion sometimes 

 affording bluish layers of siliceous limestone ; all often of a marly 



nature, easily disintegrating, forming the angular gravel of the 

 Glades and liberating their siliceous and calcareous fossils. 



List of Species, 



1, 



2. 



3. 



4. 



5. 

 6. 



8. 



9. 

 10. 

 11. 

 12. 

 13. 



14. 

 15. 



16. 



n. 



18. 

 19. 

 20. 

 21. 

 22. 

 23. 





u 

 u 



Astrocerium constrictum^ Hall, 



venustiun ? " 

 ? n, sp. 

 Lichenalia, n. sp. 

 Stromat opera, n. sp. 

 Ceramopora, n. sp. 

 Stictopora crassa, Hall. 

 Fenestella elegans, " 



tenuiceps? Hall. 

 n. sp. 



Favosites gotlilandica. Lam. 



" niagarensis, Hall. 

 Syringopora, n. sp. 

 Catenipora escharoides, Lam. 

 Streptelasma calicula, Hall. 

 " n. sp. 



Cyathophyllumt three n. sp. 

 Cystopliylluni ? 

 Car}*ocrinus, Troost's sp's, 

 Pentremites Reinwardtii, Troost. 

 Balanocriuus sculptus, Troost. 

 Eucalyptocrinus, Troost's sp's. 

 Gilburtocrinus Aniericanus, Troost 



24. 

 25. 

 26. 



27. 

 28. 

 29. 

 80, 

 31. 

 32. 

 33. 

 34. 

 35. 

 36. 



37. 



38. 



39. 

 40. 

 41. 

 42. 

 43. 

 44. 

 45. 

 46. 



Platycrinus Ann Dixoni, Troost, 

 Cupellaeorinus, sp's. of Troost. 

 Haplocrinus, " " 



Lepto^na depressa, Sowerby. 



" subplana, Conrad. 

 Spirifer crispns, Dalman. 



nndescribed. 



« 



undulatus ? 



Calceola sandalina, Lam. 



Atrypa obtuso-plicata. Hall. 



•' rugosa, HalL 



" leevis? 



** tln-ee sp's. tuides. 



aspera, Dalman. 



retieulatua, " 



Wilson i, Sow. 

 i elegantula^ Dalman. 

 Lybrida, Sow. 

 punctostriata? HaU. 



Pentamerus oblongus. 



" galeatus, Dalmaa 



Platyostoma niagarensis, Hall. 

 Phacons Hausmanni. 



a 



u 



it 



ir 



IV. The Black Slate. 



i 



This group, or stratum, cropping out around the escarp- 



1« 



nients of the basin, forms a well defined horizon. (See map.) 

 is ah'eady known, through the notices of Troost and others, as a 

 brownish black slate, often bituminous, and containing iron py- 

 rites, which is especially abundant near the base of the stratum. 

 When exposed to damp air and at the same time protected from 



* 



