18 Phosphate Rocks of South Carolina, 
inform the good people of Charleston that their czty 
ts built upon a bed of animatcules several hundred feet 
in thickness, every cubic inch of which is filled with 
myriads of perfectly preserved microscopic shells. 
These shells, however, do not, like those beneath 
Richmond and Petersburg, etc., belong to the silicious 
infusoriz, but are all derived from those minute calca- 
reous shelled creatures called by Professor Ehren- 
burg Polythalamia. You are aware that Ehrenburg 
proved chalk to be chiefly made up of such shells, 
and you doubtless will be delighted to learn that the 
Tertiary beds, beneath your city, are filled with more 
numerous and more perfect specimens of these beau- 
tiful forms, than I have ever seen in chalk or marl 
from any other locality. These forms are destined 
to be of great value in geology, and when the precise 
position of the formation beneath Charleston shall be 
fixed, and the forms belonging to cach bed determined, 
we shall then have so perfect a guide to the geology 
of a large portion of our Southern country, that by a 
mere glance through the microscope at portions of 
strata, scarcely enough to be seen by the naked eye, 
their characteristic fossils may be seen, and their true 
position in the series determined. It will be a great 
labor, however, to give the subject all the develop- 
ment it needs.” 
There are comparatively few oyster or hard shells, 
or corals found in the Eocene Marl. The Ashley 
Bed is about two hundred and sixty feet thick, as 
ascertained from the Charleston Artesian Well borings, 
and rests upon the Cooper River Marl Beds, which, 
