v 
16 GEOLOGICAL SURVEY OF ALABAMA. 
All these displacements of the strata are such as would 
have resulted from the action of an immense force coming 
from the soutueast, by which the strata were pushed up in- 
to folds or wrinkles, lapped over in many cases towards the 
northwest, and in other cases, fractured along the tops of 
the folds, and the beds on one side, the southeast, pushed 
or slipped up over those on the northwest, as is seen in the 
great faults named. This displacement in the great bound- 
ary fault amounts to ten thousand feet; in the case of the 
interior fault from seven to fifteen hundred feet. Of course 
this difference in the altitude of the strata on the two sides 
of the faults does not now exist, and possibly never did, for 
denuding forces have been active from the beginning plan- 
ing off the high places and reducing all to a common level, 
as may be seen for instance, at Helena, where the Cambrian 
and upper measures of the Cahaba Field, which in their 
original position are ten thousand feet or more apart, now 
rest side by side at the same level on the two sides of the 
great fault. 
The small faults or “hitches” in the measures along the 
northwest edge of the Blocton basin, also result from the 
action of the same forces, only these faults are much more 
limited in width and the amount of displacement mueh 
less. From the same causes also result the curving of the 
ends of the Eureka, the Helena, the Acton, and the Henry- 
ellen basins, the gentle undulations of the measures in the 
anticlinal and synclinals of the Montevallo, Blocton, Dry 
Creek, Dailey Creek, and Lolley Basins, as well as the gen- 
eral southeast dip of the measures of the field taken as a 
whole. 
Along these faults it is the rule to find the upturned 
measures on the north and northwest side of the fault, 
standing at a much steeper angle of inclination than do the 
older measures on the south and southeast sides, which 
have slidden upon and over them. This is seen all along 
the great boundary fault, where the upturned edges of the 
coal measures stand vertical, hence our name of “vertical 
measures” to designate them. West of Montevallo, as we 
have seen above, these measures have been pushed over 
even past the vertical, and completely overturned, so that 
