A Contribution to the Geologic History of the Floridian Plateau. 16& 



the Key West oolite, besides deposits of non-fossiliferous sands. There 

 are estuarine deposits along the lower courses of some streams and stream 

 terraces. The respective areas of the various marine deposits will be 

 briefly outlined in order to determine the physical conditions prevailing 

 over those areas during the deposition of each kind of material. 



COQUINA. 



Coqtiina is composed of more or less water-worn molluscan shells 

 embedded in a matrix of calcium carbonate and sand. The degree of 

 cementation varies from that sufficient for use as building stone, as in the 

 neighborhood of St. Augustine, to very loose aggregation. The loose 

 aggregations of course grade into shell marls. Coquina occurs along 

 the Florida east coast southward from St. Augustine to beyond Palm 

 Beach, as far as Boca Ratone, forming in its more southern exposures 

 a portion of Sanford's Palm Beach limestone; in fact the Palm Beach 

 limestone extends northward and some of the east coast Pleistocene 

 coquina may be referable to it. Localities at which this kind of rock 

 has been observed are St. Augustine, Ormond, Mims, and Canaveral,* 

 north of Palm Beach; and south of the last-mentioned place at Linton,* 

 Hillsboro Inlet, and Boca Ratone. Griswold says, concerning the southern 

 localities examined by him: 



About 30 miles north of New River, at Linton, another examination was 

 made. A cross-bedded fragmented rock was abundant, but contained considerable 

 quartz. Coquina was also abundant, and the two rocks were found interbedded. 



At Palm Beach and vicinity the Coquina and fine fragmental rock also occur 

 closely associated; the Coquina perhaps predominates. This is about 20 miles 

 north of Linton. * * * 



A trip to Cape Canaveral disclosed there a rock which may well represent 

 the fine fragmental rock of Palm Beach and Linton. The quantity of quartz is 

 greater, the quartz grains are larger, and the rock less coherent than to the south. 



The following record of a well drilled at Delray by Edwin T. King, 

 for O. Eleasen, shows that the coquina is interbedded with sand. 



Record of well at Delray. 



Depth. 



Thickness. 



Surface sand. 



Coquina 



Quicksand. . . 

 Coquina 



Feet. 

 o to 



108 

 119 



Feet. 



A list of a collection of fossils obtained here by Mr. King from a 

 depth of 118 feet is given below. 



Oculina sp. 



Si derastrea radians (Pallas). 

 Porites divaricata Le Suetir. 

 Cidaris tribuloides Lamk. 

 Tornatina buUata Kiener. 

 Terebra dislocata Say. 



dislocata var. indenta Conrad. 



protexta Conrad. 



Terebra concava Conrad, var., may be 



new. X 

 Conus fioridanus Gabb. 

 Drillia digitalis Reeve. 

 Oliva retictilaris Lam. var. 

 Olivella mutica Say. 

 Marginella opalina Stearns. 

 Latirus brevicaudata Lam. ? x 



» Griswold, Mus. Comp. Zool., Bull., vol., xxviii, p. 59, 1896. 



