29 INTRODUCTION. 
tion which is so remarkable, and passes through the whole 
extent of South Alabama, called the Shell Limestone 
Country, embraces this bluff. The southern edge of this 
Formation commences about ten miles south of this place. 
It is, no doubt, about one hundred miles wide from south 
to north, in this part of the state. It is believed that this 
limestone tract takes its beginning at the gulf, in the 
neighbourhood of St Mark’s and Tallahassee, and extends 
from that point north west, through the whole of this and 
the state of Mississippi, and is said to terminate at the 
Chickasaw Bluffs, in West Tennessee. This Formation 
is probably of the same nature with that which extends 
through South Carolina, Georgia and Florida, parallel to 
the sea coasts, and terminates on the gulf of Mexico, at 
or about St Mark’s. The course of this Atlantic Forma- 
tion is from the north east to the south west. The coun- 
try between the Shell Limestone tract in this state, and 
Mississippi and the gulf, is a barren sand, with the long 
leaf pine (Pinus australis), &c. as its principal forest 
growth.” 
With the specimens then sent, was received a short stra- 
tagraphical account of each which is here inserted. 
“No. 1 isa specimen of the stratum, from the water 
line up about one hundred and twenty feet, extending be- 
low the water as far as can be discerned by the eye.” 
This specimen was nearly six inches square. It is a soft 
calcareous rock, containing eleven per cent of carbonate of 
lime,* with occasional specks of mica, and small cells filled 
with carbon. In breaking it up, to present as much surface 
as possible, I examined it carefully, to endeavour to identify 
the fossils contained in it, but these could only be seen ina 
very imperfect state, and almost universally in fragments. 
They consisted generally of Flustre, Cardie, Corbule, Os- 
* To the kindness of Dr J. K. Mitchell I am indebted for the analysis 
of these specimens. 
