IDEAL SECTIONS SHOWING THE FORMATION or MANGANESE-BEARING 

 CLAY FROM THE DECAY OF THE ST.CLAIR LIMESTONE. 



dBoONE CHERT MANGANESE-BEARlNfc CLAY rTllZARD LIMESTONE 



EDSACCHAROIDAL SANDSTONE 



ST.CLAIR LIMESTONE; 



Fia. 1. ORIGINAL CONDITION OF THE ROCKS. 



FIG. 2. FIRST STAGE OF DECOMPOSITION. 



FIG. 3. SECOND STAGE OF DECOMPOSITION. 



FIG. 4. THIRD STAGE OP DECOMPOSITION. 



FIG. 64. Geological sections illustrating the formation of the manganese 

 ores in Arkansas. After R. A. F. Penrose, Oeol. Survey of Ark., 

 1890, Vol. L,p. 177. 264 



