VALLEY REGION DETAILS ; CAHABA VALLEY. 163 
run strictly parallel to the strike or outcrop of the rocks, 
but runs in a sinuous line now into the very edge of the Coal 
Measures, now out into the valley so as to leave some of the 
strata underlying the Coal Measures between the Cambrian 
and the Warrior Field. As in the preceding cases, the beds 
immediately to the northwest of the fault usually stand at a 
high angle, sometimes vertical, while in places they have 
been pushed even past the vertical so as to be reversed. © 
On the northwestern side of the valley nearly its whole 
length, we find the first beds of the Warrior Coal Field, in 
this nearly vertical position, making a rock wall, through 
which the streams have cut their way at a few points, by 
deep and narrow gorges. 
In cases where the strata bordering a fault are tilted up 
at these very high angles, it rarely happens that the full 
thickness of the beds concerned is present, but some are 
pinched out almost completely, others appear in full force, 
while still others are seen in exceptional thickness. Where 
beds of coal are among the strata, the thickness is nearly 
always found to be extremely variable, the beds thinning 
down to a few inches and thickening up to several feet 
within a distance of afew yards. 
There is hardly a place along the western side of Jones’ 
Valley where these irregularities are not to be seen. At 
North Birmingham, in one place, the Cambrian of the valley 
is, by the regular fault on that side, brought in contact with 
the upper part of the Knox Dolomite. Now we should 
expect to find beyond these beds of Knox Dolomite, first th® 
Trenton, then the Clinton, the Black Shale, and Sub-Car- 
boniferous, then the Measures of the Warrior Field; and 
very often such a succession of the beds does actually occur ; 
but at the point named, the Knox Dolomite is in immediate 
contact on that side with the Coal Measures, the interven- 
ing strata above enumerated, having been pinched out or 
engulfed in a second fault. 
CaHABA VALLEY. 
This is the name given to the valley which separates the 
Coosa from the Cahaba Coal Field, and under this name it 
extends from near Odenville to Montevallo, but its con- 
