Keyes — Devonian & Carboniferous in Upper Mississippi Valley. 359 



Silurian to the upper Burlington, and where there occurred 

 an abundance of fossils. In order that the accompanying 

 tabular lists may be understood in their full significance the 

 section of the rocks exposed at Louisiana is given below, es- 

 sentially as when first published several years ago,* except 

 that for present purposes smaller zones are recognized and 

 some modifications in thickness are made in order to have the 

 section more expressive of the conditions at the town itself. 



SECTION AT LOUISIANA, MIS80UBI. 



I^eceat 



Upper j 

 Burlington - * 



'[ 



Lower 

 Burlington. 



Chouteau. 



Hannibal 



Louisiana 



Western - 

 Hamilton 



Niagara .. 



Hudson. . . 



1 



21. 



20. 

 19. 

 18. 



17. 

 16. 



15. 



14. 

 13. 

 12. 



U. 



10. 



9. 



Soil and red residuary clay, with chert frag- 

 ments 



Limestone, brown, with thinly bedded and 

 nodular chert 



Limestone, compact, thin-bedded, encrinital, 

 with much gray chert in bands and nodules. . 



Limestone, yellowish brown, rather soft, en- 

 crinital 



Limestone, bluish, fine-grained, siliceous 



Limestone, massive, white, encrinital, coarse- 

 grained (upper white ledge) 



Limestone, brown, encrinital, with irregular 

 chert bands and nodules, and occasional thin 

 clay partings 



Limestone, white, very heavily bedded, encrini- 

 tal, chief quarry stone (lower white ledge ") . . 



Limestone, brown, encrinital, heavily bedded.. 



Limestone, yellow, massive or heavily bedded, 

 rather soft, fine-grained 



Shale, brown, sandy, passing into soft sand- 

 stone locally 



Shale, green, sandy above 



Limestone, buff to gray, compact,, very fine- 

 grained, in layers 4 to 6 inches thick, similar 

 to lithograph stone in texture 



Limestone, similar to above 



Limestone, similar to above, layers thicker and 

 separated by buff sandy partings 



Shale, bufE, sandy, 2 to 6 inches 



Shale, green 



Shale, black, fissile. 



Limestone, magnesian, buff, massive. 

 Oolite, white, massive 



Shale, blue, with thin bands of limestone. 



Feet 

 4 



28 



18 



4 



4 



12 



20 



9 

 6 



12 

 60 



34 



8 



6 

 k 



2 

 4 



4 

 7 



40 



* Am. Jour. Sci., (3), vol. xuv. p. 448, 1892. 



