Report of U S. National Museum, 1 899. — Merrill 



Plate 10. 



IDEAL Sections showing the formation of manganese-Bearing 



CLAY FROM THE DECAY OF THE ST.CLAIR LiMESTONE. 



laiyBooNE Chert L_^ Mangane se-Bearing cLay LzUIzaro Limestone 

 LIj St. Clair Limestone CDsaccharoidal SANOSTONr 



FIG. I. ORIGINAL CONDITION or the: ROCKS. 



FIG. 2. FIRST STAGE OF DECOMPOSITION. 



FIG. 3. SECOND STAGE OF DECOMPOSITION 



FIG. 4. THIRD STA6E OF DECOMPOSITION. 



Section showing the Formation of Manganese Deposits from Decay of 



Limestone. 



After Penrose, .\imnal Report (k'ologieal ,'^nrvey of Arkansas. I, 1«90. 



