236 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213. 
compression in a northwest-southeast direction. From evidence 
obtained in adjoining regions, it appears probable that this compres- 
sion, and the subsequent folding, began in early Paleozoic time, and 
continued at intervals up to its culmination at the close of the Car- 
boniferous. It resulted in the formation of folds and faults in the 
valley rocks and in the development of a slaty cleavage or schistose 
structure in the older rocks to the east, while the latter were thrust 
upward and westward relatively to the former, producing the great 
Cartersville fault. The region west of the Cartersville district is 
occupied b} T a broad, gentle syncline of Knox dolomite. This mas- 
sive formation appears to have resisted folding, and to have trans- 
mitted the thrust in such a manner that while its own beds retained 
very nearly their original horizontal position, the beds coming to the 
surface in narrow belts on either side were intensely folded. Thus 
the shales which occupy the western portion of the district are highly 
contorted, and* are doubtless intersected by numerous small faults. 
Also, considerable slaty cleavage has been developed in them. The 
Weisner quartzite likewise resisted folding to some extent, although 
its beds were thrown into the form of an anticline with numerous 
irregular minor folds. The irregularity of the anticline is shown by 
the character of its contact with the overlying limestones to the west. 
In addition to the folding which the quartzite has undergone, it is 
doubtless intersected by numerous faults, the evidence of which is 
seen in its crushed and brecciated condition at many points. Owing 
to the character of the outcrops, however, these faults generally can 
not be located or traced. 
The folding referred to brought about certain mechanical and 
chemical conditions favorable for the deposition of mineral deposits, 
and hence has an important bearing on the economic geology of the 
district. It is frequently observed that the originally compact vitre- 
ous quartzite is converted into a rock somewhat resembling jasper. 
Chert from the overling limestone, under similar conditions, is 
altered in the same manner; and it is often impossible to distinguish 
between the final products of the alteration of rocks originally wholly 
unlike. Portions of the quartzite have been converted into a spongy 
rock, containing innumerable fine cavities lined with small quartz 
crystals and stained with yellow ocher. This form of alteration is 
probably due to the circulation through the rock of thermal waters, 
by which the quartz was taken into solution and in part redeposited, 
along with more or less iron oxide. 
The line marking the Cartersville fault departs in this region from 
its rather regular course across northwestern Georgia, making a dis- 
tinct embayment to the east in passing around the belt of Lower 
Cambrian quartzite and limestone. On either side of this region the 
fault brings the soft slates of the Ocoee series in contact with Cam- 
brian shales of a similar character. The actual plane of contact 
