And the “Great Carolina Marl Bed.” 39 
Phosphate of Lime come from? It follows, there- 
fore, that if these doves had contributed to furnish the 
Phosphoric Acid to the rocks, (as some suppose, ) 
they would have been deprived of all they possessed , 
and, therefore, it seems very plain, that from the fecal 
matter (dung and urine) deposited by land guadrupeds 
during a series of ages, dissolved by rain, and its 
juices carried down to be imbibed by the Marl nod- 
ules, atom after atom as the Carbonate of Lime was 
dissolved out of the rock, has been derived the chemi- 
cal agent which converted the Eocene Marl nodules 
into Phosphate-rocks. To the bones which are buried 
with them was imparted also the additional amount 
of Phosphoric Acid they are now found to contain, in 
excess of that they possessed when in a recent or 
living state, and not as has been suggested, from the 
excrement of birds. 
This theory regarding the conversion of the Car- 
bonate of Lime rocks into Phosphate of Lime, was 
submitted by us in October, 1867, (just after reading 
Ansted’s Lectures on Practical Geology, alluded to 
in this work as having been received from England 
the day of the discovery of the great value of the 
Phosphate-rocks,) to Professor Joseph Leidy, Professor 
Samuel H. Dickson, and several other scientific gen- 
tlemen of Philadelphia, and obtained their ready con- 
currence.* Sometime in the beginning of 1869, or 
late in 1868, Dr. F. Peyre Porcher, of Charleston, the 
distinguished author of “ Resources of our Fields and 
* George T. Lewis, Esq., Frederick Klett, Esq., and Mr. Willian, 
Chemist. 
