162 GEOLOGICAL SURVEY OF ALABAMA. 
of the break and the sliding up of the Cambrian beds. Be- 
yond this point the strata of the Cahaba Field soon flatten 
down, and assume a dip to the southeast, these southeast- 
erly dipping beds taken together with the vertical ones just 
mentioned, constituting a synclinal basin with its axis very 
near to the southeastern edge. The coal beds occurring in 
the vertical measures are undoubtedly the same as those 
occurring in the flatter measures just beyond, but we have 
the authority of Mr. Squire for saying that it is in most 
cases impossible to correlate the seams in the vertical 
measures with those that have not been so much disturbed. 
It is evident from this that the fault has broken up and dis- 
placed these coal seams so that they do not now occupy 
their relative positions in every case. As we cross the 
OCahaba Field we notice that the strata, with local exceptions, 
have a dip to the southeast, and the prevailing dip shows 
that the strata are gradually rising into another anticlinal 
fold which also includes all the underlying formations of 
Shades Valley, Red Mountain, and of the Birmingham 
Valley, as far west as the foot of the flint ridge “a” upon 
which is the cemetery. Here occurs another fault of the 
same nature as the one first described, except that the 
amount of the displacement is not by any means so great, 
At the eastern foot of this flint ridge, we find the strata 
standing in many places nearly vertical, as they do at 
the eastern edge of the Cahaba Coal Field. Along 
this line of fault the Cambrian of the valley lies in 
contact with the strata of the Knox Dolomite in most 
places, but an occasional bed of limestone and numerous 
fragments of red ore containing fossils which belong to the 
Clinton fauna, show that the Trenton and the Red Mountain 
or Clinton groups of the upper Silurian formation have not 
been entirely removed in the erosion of the valley. 
Beyond the flint ridge just mentioned, we come, in going 
westward, again to the Cambrian strata, which, in a great 
measure, form the underlying beds of this second valley 
known as ’Possum Valley. Across it we come to a third 
fault which brings this Camlerian formation in contact with 
overlying beds, such as Trenton, Clinton, Sub-Carbonifer- 
ous, and Coal Measures; for the fault does not by any meang 
