36 BUREAU OF AMERICAN ETHNOLOGY [bull. 52 



the openings between tlio individual shells, though in some localities 

 the process of cementation lias proceeded far enough to produce a 

 rather compact fossUiferous limestone. There is usually more or less 

 sand present, which is commonly in the form of thin lamina; separating 

 the shell beds, and various gradations from sand rock to shell rock 

 may be noted along the Florida coast." 



Sellards quotes from an account published by James Pierce in 1825, 

 in the American Journal of Science : 



"Extensive beds of shell rock of a peculiar character occupy the 

 borders of the ocean in various places from the River St. Johns to 

 Cape Florida. Tliey are composed of unmineralized marine shells 

 of species common to our coast, mostly small bivalves, whole and 

 in minute division, connected by calcareous cement. I examined 

 this rock on the Isle of Anastasia, opposite St. Augustine, where it 

 extends for miles, rising 20 feet above the sea and of unknown depth. 

 It has been penetrated about 30 feet. In these quarries horizontal 

 strata of shell rock of sufficient thiclvness and solidity for good build- 

 ing stone alternate with narrow parallel beds of larger and mostly 

 unbroken shells, but slightly comiected. • • • The large Spanish 

 fort and most of the public and private buildings of St. Augustine 

 are constructed of this stone. The rock extends in places into the 

 sea with superincumbent beds of new shells of the same character." 



In the report from which these quotations are given the Quaternary 

 is divided into Pleistocene and Recent and the coquina is placed in 

 both Pleistocene and Recent, along with beach sands and eolian 

 deposits. The various deposits of coquina along the coast have 

 repeatedly been observed and studied by both Dall and Vaughan, 

 and their Quaternary age has been determined by these observers. 



From the example of the coquina of the Florida coast we learn that 

 indurated formations may be even as modern as the Recent epoch. 

 They may also be Pleistocene, and the question of age determination 

 depends in a large measure on their relation to other formations or 

 to physiogi'aphic features. Paleontologic evidence also has bearing, 

 but there are two conditions which may qualify it. The life range of 

 species may cover the time of development of difi'erent masses of 

 coquina which are physiographically distinguishable, for the move- 

 ments and accidents of coastal development are constantly affording 

 new and different conditions under which shells may be assembled 

 and cemented. Again, in case a coquina contains remains of both 

 living and extinct species, the latter belonging to an older formation 

 from which they may be derived, we can not accept with any confi- 

 dence the evidence of these older fossils as to the age of the coquina. 



The coquina of the Argentine coast may then be studied with 

 reference to its constitution, hardness, and the capacit}^ of existing 

 agencies to cement it; in regard also to its relation to the existing 



