I ORIGIN OF THE ROCKS OF THE CAHABA COAL 
FIELD AND ADJACENT REGIONS, AND THE 
AGENCIES WHICH HAVE BROUGHT 
THEM INTO THEIR PRESENT 
POSITIONS. 
The map and sections of Mr. Squire exhibit the structure 
of the Cahaba Field in sufficient detail, but a few words ex- 
planatory of the relations of this field to the others, and to 
the valleys lying between them seem to be required. 
It is the commonly received opinion among geologists, 
and an opinion capable of demonstration, that the older 
stratified or bedded rocks of the Appalachian region of the 
United States, in which is included Cahaba Coal Field and 
the regions above alluded to, were formed partly out of the 
detritus of a previously existing land mass lying to the east- 
ward of the present shore line of the Atlantic ocean, and 
partly out of the calcareous and siliceous matters accumu- 
lated through the agency of living organisms, in the depths 
of an inland sea which formerly occupied the position of 
the greater part of the present United States. This detritus, 
washed down by rains and transported by rivers, was finally 
spread upon the floor of this inland sea. Naturally by far 
greater part of this land waste would be deposited close to 
the shore line, while only the finer sediments such as silt 
and mud would be held in suspension long enough to be 
carried far out to sea and be deposited there, and in the 
clear and moderately deep waters of the sea at a distance 
from the shore would flourish the corals, and other organ- 
isms that formed the limestones and part of the chert or 
siliceous matters. If the floor of this interior sea remained 
stationary while receiving these sediments, it is easy to see 
that it would very soon be silted up by the washings from 
the land, and that no great thickness of variety in the sedi- 
ments would be seen at any one place; we should not find, 
