364 CHESTER K. WENTWORTH 
total displacement was less at D than at C. It seems likely that 
there was some slight displacement beyond Skegg Gap and into 
Dickinson County along the Pine Mountain fault before it was 
intersected by the Russell Fork cross fault. 
In following chronologically the development of the Jacksboro— 
Pine Mountain line of faulting the Russell Fork cross fault was 
temporarily omitted. The history of its development is corre- 
lated with the events described above, as follows: 
Only after there had been considerable development of the Pine 
Mountain anticline at C, and some shearing along the Jacksboro 
cross fault, was the skewing of the Cumberland block felt at the 
northeast end. Its first expression was the development of a 
tension or normal fault starting at F (Fig. 2) and extending toward 
E with continued twisting of the block. 
The presence of the Little Pawpaw fault, which appears to be 
primarily the result of such tension incident to twisting, leads the 
writer to believe that the point, or, perhaps more correctly, the 
area of pivoting, was somewhat to the north of E. On the other 
hand, evidence of somewhat more pronounced compression along 
the fault from D, part of the distance toward E, seems to indicate 
that compression was even at first dominant in that part of the 
line. It seems therefore probable that the region of pivoting is 
located between D and E but somewhat nearer the latter. 
After the extension of the Pine Mountain fault beyond Skegg 
Gap and the extension of the Russell Fork cross fault beyond E 
as a normal fault, the accumulation at the northeast end of the 
block of the northwestward-trending stresses, which had long 
been operative at the Tennessee end of the block, reached the 
critical point, and the northeast end was broken loose along the 
line largely determined by the pre-existing normal fault. The 
line of this break intersected the Pine Mountain fault at Skegg 
Gap, stopped farther movement in that fault east of that line, and 
permitted the Cumberland block to be thrust not over two miles 
northwestward at this end. Since the Russell Fork fault line 
forms an angle of over 90° with the line of the Pine Mountain 
overthrust, the overthrusting of the east end of the block brought 
about compression along the whole extent of the Russell Fork 
