280 GEOLOGY OF ILLINOIS. 



1. Soil and Drift. Not measured. 



2. Sandstone, soft* ....................................................... 1 5 



3. Yellow clay shale ...................................................... 1 7 



4. Bluish clay shale .................................... ................. 6 6 



5. Limestone ....................................................... 4 6 



6. Shale ................................................................ 2 2 



7. Limestone ............................................................ 2 11 



8. Clay ................................................................ 2 



9. Shale ................................................................ 4 



10. Limestone ........................................................... 5 



11. Shale ........................................................ . ....... 1 1 



12. Limestone ........................................................... 6 



13. Shale ................................................................ 2 1 



14. Limestone ............................................................ 11 



16. Shale, with a little thin-bedded limestone .................................. 2 5 * 



16. Argillaceous limestone ........................................ ....... 4 2 



17. Limestone and a little shale ..................... ........................ 1 8 



18. Shale ................................................................ 11 



19. Limestone .................................................. . ....... 3 



20. Shale ................................................................ 9 



21. Limestone ............................................................ 1 



22. Thin-bedded limestone, with chert ........................................ 5 



23. Limestone, a little cherty ............... . ............................... 1 



24. Chert ............................................................... 4 



25. Limestone ............................................................ 2 1 



26. Shale, with thin layers of limestone ...................................... 7 



27. Limestone, very cherty, to the water ...................................... 8 



39 2 



All below No. 4 belongs to the Keokuk. The thickness of these strata are 

 quite variable, but this section serves to give a general idea of their lithological 

 character in this region. Some idea of their variableness may be had from the 

 following section, made at Shoemaker's quarry, which is but a short distance from 

 this point : 



FEET. IN. 



1. St. Louis beds 3 8 



2. Limestone 2 7 



3. Shale 1 9 



4. Limestone, very shaly 8 



5. Limestone 2 11 



6. Shale 7 



7. Limestone ? 



Lower than this, the quarry was not worked, and the rock was not exposed. 

 This quarry lies near the top of the bluff, and corresponds very nearly with the 

 upper part of the other section. North of the immediate vicinity of the South 

 Henderson, this limestone is not exposed, and probably thins out rapidly in 

 that direction, as the Burlington limestone appears but a few miles north of this 

 on South Smith creek. 



