362 CHESTER K. WENTWORTH 
MECHANICS 
The history of the deformation (Fig. 8) is conceived to be as 
follows: 
The rocks of the Cumberland block were subjected to strong 
lateral compression applied from the southeast. The thicker sedi- 
mentary rocks west of A (Fig. 2, p. 355) seem not to have yielded 
as did those to the east, and acted as a buttress against which the 
rocks to the east were deformed. ‘The compressional stress was 
much more intense at the Tennessee end of the block and the first 
result of the stress was the folding of the Powell Valley anticline 
and of the lateral anticline which later broke and formed the 
Jacksboro cross fault. Between A and B Keith™ found evidence 
of this now broken anticline which was the result of deformation 
of the rocks of the Cumberland block against the more competent 
buttress on the west. 
After the Powell Valley anticline had been in large measure 
formed and the Jacksboro cross anticline had probably reached its 
full development, the stresses were then transmitted across the 
block, and yielding farther northwest resulted in the folding of the 
rocks into the Pine Mountain anticline. It is probable that by” 
this time overthrusting and shearing to the northwest had com- 
menced at the southern end of the Jacksboro cross anticline, for 
the movement of the rocks of the Powell Valley anticline north- 
westward differentially with respect to the nearly undisturbed 
rocks on the west had already been very considerable. With the 
continued crumpling of the Pine Mountain anticline, the Jacksboro 
cross fault developed progressively toward the northwest, and, 
when it reached the then position of the corner C of the block, 
initiated the great Pine Mountain fault. 
There had by this time been considerable skewing of the entire 
block which was pivoted at or near its north corner, with the 
result that the corner of the block at A had been thrust more 
extensively on the rocks to the west than had the corner at C. 
The overthrust to the west in the Jacksboro cross fault is, how- 
ever, believed to be only the smaller movement incidental to the 
skewing of the block, while the main movement in this fault was 
t Arthur Keith, U.S. Geol. Survey Geol. Atlas, Briceville Folio No. 33 (1896). 
"wre 
