GEOLOGY OF GRAVES MOUNTAIN 



205 



biotite. Numerous dikes of basic igneous rocks, mainly diabasic in charac- 

 ter, ranging up to several hundred feet in width, occur. They are clearly 

 intrusive in character since they cut across the foliation of the schists irregu- 

 larly. Likewise the sulphide ore bodies (chalcopyrite, galena, sphalerite, 

 and pyrite) developed in a shear zone in the sericite schists approximating 

 a northeast-southwest direction and crossing at a small angle the schistos- 

 ity, are cut across and faulted by some of the dikes of basic rock. The 

 rocks are cut by numerous joints aiid in places by faults. Columns I, 

 II, and III in the table of analyses below show the composition of some 

 of the rocks near the Seminole mine. 



The rocks of the region are deeply decomposed by atmospheric agencies 

 so that relatively few exposures are seen. They are strongly foliated, the 

 general direction of strike being northeast-southwest, with local variation 

 observed from place to place. At Graves Mountain and further northward 

 at the Seminole mine the dip is to the northwest. Southeastward from 

 Graves Mountain about six miles, at Amity Postofiice, and thence south- 

 ward to Little River the schists likewise dip to the northwest.* 



Analyses of porphyry, gneiss, and schist, Lincoln and McDuffie Counties, Georgia. '\ 

 (Dr. Edgar Everhart, analyst). 



* Veatcli, Otto. Personal communication, January, 1915 

 t Jones, S. P., Bull. 19, Ga. Geol. Survey, 1909, pp. 55-62. 



