176 GEOLOGICAL SURVEY OF ALABAMA. 
lands of the same formation, and the continuity of the ridge 
is interrupted. We have already intimated that in a modi- 
fied form the synclinal of Blount Mountain is the continua- 
tion of this. 
Going northwest beyond the flint ridge we pass over the 
strata of the red lands of the Knox Dolomite, then over a 
second belt of Cambrian, all dipping back below the ridge, 
and rising to the northwest into the second anticlinal, here 
called "Possum Valley. The summit of this anticlinal, like 
that of Jones’ Valley, marks the line of another thrust fault 
similar to that of the flint ridge, though much more irregu- 
lar in its course, for while, along the border of the flint ridge, 
the fault brings the Cambrian as a rule in contact with the 
chert of the Knox Dolomite, with here and there an excep- 
tion where it is brought up against Trenton and Clinton, in 
this second fault the Cambrian is brought up in contact 
with Knox Chert, with Trenton, with Clinton, with Sub- 
Carboniferous, and even with the measures of the Warrior 
Field. This fault hence shows a much greater variation in 
the amount of displacement than the one first named and 
described. This may be made clearer by reference to the 
section above referred to, and to the map. This fau!t runs 
along nearly parallel to the line of the Birmingham Mineral 
Railroad above Boyle’s, up into Murphree’s Valley. Above 
the line of the South & North Alabama Railroad, it will be 
seen that the fault is at some distance from the edge of the 
Warrior Field, and that strips of the following formations 
intervene between the two, viz, Knox Dolomite, Trenton, 
Clinton and Sub-Carboniferous, and that the fault passes 
from the western side of "Possum Valley across to the 
eastern side of Murphree’s Valley. As we approach Boyle’s 
Gap, the width of the belt of intervening measures decreases 
some of the formations seem to be pinched out completely 
others seem to be partly cut out, and none of them retain 
their full characters. The diagram (cross-section) shows 
the whole series from the Knox Dolomite up to the Sub- 
Carboniferous as intervening between the fault and the edge 
of the Warrior Field, which is in reality the case in some 
places, but we need only to examine the map to see how the 
fault runs irregularly along the border of the Warrior Field, 
