152 Bulletin of Laboratories of Denison University [Voi. xii 



rocks are yet known to occur within the limits of the area. 

 The manganese-deposits are limited to the residual decay rest- 

 ing^ on and derived from only three of the formations, namely, 

 the Weisner quartzite, Beaver limestone and Knox dolomite. 

 These formations are described in sufficient detail under the 

 Cartersville and Cave Spring districts of this paper, and they 

 need not be repeated here. (See Fig. 2). 



Structure. — The region is one in which the strata have 

 been thrown into great northeast-southwest folds from horizon- 

 tal pressure applied in a northwest-southeast direction. In ad- 

 dition to the folding, continuation of the same compressive 

 forces resulted in fracturing and faulting the strata over most of 

 the area. To the northwest of the Coosa valley the area is one 

 of open folds, and faulting is less conspicuous. Folds of the 

 anticlinal, synclinal and monoclinal types are represented in 

 many examples of northeast-southwest-trending ridges pre- 

 served in the harder and more resistant rocks. 



In the region to the south and southwest of Rome, the 

 structure is more complicated, largely by reason of the folding 

 having been quite or entirely obliterated by subsequent fault- 

 ing, and by deposition-overlaps and abrupt lithologic changes.^ 

 Two classes of faults, which differ materially from each other, 

 characterize the area. These are designated by Hayes^ as {a) 

 major thrust faults, and {U) minor-thrust faults. 



The major-thrust faults are characterized by great horizon- 

 tal displacement and low inclination of the fault-plane. Three 

 faults of this type have been recognized and described by 

 Hayes^ in this area, namely, the Coosa, Rome and Cartersville 

 overthrust faults. In the case of the Cartersville fault, rocks 

 of probable Algonkian age and belonging to the Crystalline- 



^ Hayes, C. W., Bulkttn, Geol. Soc. of America, 1894, vol. v., p. 472. 

 •^ Op. at., pp. 557-560. 



* Hayes, C. W., "The Overthrust Faults of the Southern Appalachians," 

 Bulletin, Geol. Soc. of America, 1891, vol. ii., pp. 141-154; "Geology of a Por- 

 tion of the Coosa Valley in Georgia and Alabama," Bulletin, Geol. Soc. of 

 America, 1894, vol. v., pp. 465-480. 



