2o8 Bulletin of Laboratories of Denison University, [voi. xii 



rock are seldom seen. A thickness of lOO ft. and more of the 

 residual decay is frequent over the district. Difference in com- 

 position of the sub-terranes shows equally as marked a differ- 

 ence in the chemical and physical properties of the derived 

 decay. The decay derived from the limestone is usually a 

 deep-red ferruginous clay with or without admixed chert frag- 

 ments, as the original rock was chert-bearing or not. That de- 

 rived from the harder and more resistant quartzite is a light 

 gray siliceous clay, in which the proportion of clay is usually 

 relatively smaller than that derived from the sandstone. So 

 strongly marked are the properties of the residual decay de- 

 rived from the lithologically unlike sub-terranes, that the areas 

 of originally fresh rock can usually be differentiated and traced 

 with considerable accuracy by the decay. 



The decay over the quartzite area is thickest in the valley- 

 bottoms, and thinnest near and on top of the higher and steeper 

 ridges. Along the steeper ridge-slopes exposures of the com- 

 paratively fresh and hard rock are not uncommon. On the 

 ridge-tops large reefs and broken masses of the hard quartzite 

 are frequent. The residual decay derived from the quartzite is 

 largely admixed with fragments ot various sizes of the quartz- 

 rock in all stages of decay, from partially discolored hard rock 

 to masses of loose or incoherent quartz-grains or sand. 



The Ocher-Deposits. 



As indicated on the the accompanying map. Fig. i, the 

 ocher belt has an approximate length of about eight miles in a 

 nearly north-south direction. Traced by the outcroppings and 

 the prospect-openings the belt is a very narrow one. not ex- 

 ceeding perhaps two miles in the widest point. It has its south- 

 ernmost extension at and to the west of Emerson, about two 

 miles south of the Etowah river, and is traced in a northward 

 direction, about one mile east of Cartersville, to a point north 

 and to the west of Rowland Springs. Beyond this point sur- 

 face-indications disappear and no prospect-openings have been 

 made, hence it is not possible to state definitely that this marks 

 the extreme limit of the belt to the north. 



