USEFUL METALS 



238 



tact of the Lower Cretaceous and Tertiary formation*. The ores 



arc uriirrally pi.-nlit ir or concretionary, but sometime-, they are 

 amorphous and flinty. Veatch consider.-, that the ore was formed 

 l>\ a desilicifieation of the kaolinite in the associated clays by cir- 

 culating meteoric waters carrying some chemical capable of ex- 

 tracting the silica from the hydrous aluminum silicate (Fig 117). 

 (2) In the Georgia-Alabama district the bauxite deposits ex- 

 tend from Cartersville, Georgia, to Jacksonville, Alabama, a dis- 

 tance of about 60 miles (see Fig. 118). They are found at altitudes 





FIG. 118. Geologic map of Alabama Georgia bauxite region. After 

 Hayes. (By permission of the Macmillan Company, from Ries' Economic 

 Geology.) 



varying from 850 to 950 ft. above sea level. The ores are pisolit ic. 

 or clay-like. They form pockets or lenses of variable breadth 

 and thickness in the residual clays derived from the underlying 

 limestone. According to C. W. Hayes the bauxite belongs to t In- 

 hot spring deposits. The Connasauga shales underlying the 

 Knox dolomite are thousands of feet in thickness and bear pyrites. 

 Percolating meteoric waters acting upon the sulphide of iron pro- 

 duced sulphuric acid. The sulphuric acid attacked the aluminif- 

 erous shales forming the sulphates of iron and aluminum. These 

 solutions were transported upward through the Knox dolomite 



