1/8 Bulletin of Laboratones of Denison University [Voi. xii 



stringers and masses only a few inches in thickness, which cut 

 the clay in all directions, conforming at times with the bedding- 

 planes. Many of the stringers are composed of quartz, around 

 and along which the ore is deposited as impregnations, incrus- 

 tations, and as nodules and gravel. A goodly proportion of 

 the gravel and nodular types of the ore is distributed through 

 the clays without any apparent relation to the chert-fragments 

 and masses. In most cases, however, the ore is closely asso- 

 ciated with the chert, varying from impregnations as seams of 

 knife-edge thickness to a ground-mass of ore cementing the par- 

 tially fresh and decomposed chert-fragments. (See Fig. 15.) 

 The form of breccia-ore commonly occurring in this locality is 

 shown in Fig. 15. The proportion of chert to ore of the 

 breccia-mass varies widely, from a mere film of manganese ox- 

 ide, filling the cracks of the shattered chert and binding them 

 together, to those in which the largest bulk of the mass is ore 

 containing but few small chert-fragments. 



Fig. 14 



Section in One of the Openings at the Lindale Mine, 4 Miles South of Rome, 

 Georgia, Showing the Mode of Occurrence of the Manganese-Ores. 

 A, ore-bearing clay. The black areas are manganese. The irregular areas 

 with straight parallel lines are fragments of chert and sandstone, the cracks of 

 which are filled with manganese oxide. 



IJie Tunnel Hill District. — The Tunnel Hill district in- 

 cludes the contiguous parts of Whitfield and Catoosa counties 

 in the northeast part of the Paleozoic Group. In structure and 

 topography the area quite closely resembles certain parts of 

 the Cave Spring district already described. The rocks include 

 shales, sandstones and limestones, and in age they range from 



