1 82 Bulletin of Laboratories of Denison University, [voi. xii 



soluble and impervious stratum, such as sandstone or quartzite." 

 He further says ■} 



"Favorable conditions for this accumulation occur in northwest 

 Georgia and Alabama, at the contact of the lower Carboniferous lime- 

 stones with sandstones which sometimes underlie it, and at the contact 

 of the Beaver limestone with the underlying Weisner (partzite." 



The second type of iron-ore deposits of the area is that 

 genetically related to the faults which intersect the strata and 

 are designated by Hayes as fault-deposits. 



The yellow ocher-deposits are closely associated with those 

 of manganese in the Cartersville district ; and also with the 

 iron-ores of the same area. Beginning at a distance of about 

 3 miles southeast of Cartersville, the ocher-belt has a northward 

 extension of 7 to 8 miles, confined exclusively to the Weisner 

 quartzite, which has been greatly fractured and faulted. The 

 occurrence of the ocher is entirely in the nature of replacement- 

 deposits in the shattered quartzite, — the silica of the quartzite 

 havmg been removed in solution and the hydrated ferric oxide 

 substituted.^ 



The last type of ore-deposit in the area that needs mention 

 is bauxite. The ore-bodies are distinct pocket deposits, having 

 the vertical and lateral dimensions about equal, and they are 

 inclosed in the residual clays derived from the decay of the 

 Knox dolomite. They were first shown by Hayes, ^ and after- 

 wards corroborated by the writer, ^ to represent accumulations of 

 hydrated aluminum oxide in vents or springs along the lines 

 of numerous faults which intersect the area. The source of the 

 alumina was from below, in the underlying aluminous shales of 

 the Conasauga (Cambrian) formation, and was taken in solution 

 by hot ascending acidulated waters circulating along the lines 

 of fracture. 



> Ibid., p. 412. 



* Ibid., pp. 415-418. 



^ Hayes, C. W., Sixteenth Annual Report U. S. Geol. Survey, 1895, Part III., 

 PP- 587-59J- 



* Watson, Thomas L., American Geologist, 1901, vol. xxviii, pp. 25-45. 



