SECOND ANNUAL REPORT-SOUTHERN EEORIDA. 
221 
six species, of which two are corals, one an echinoid, and twenty-three 
mollusks. The corals were not of reef-building species and Dr. 
Vaughan found several delicate pelecypod shells with both valves 
closed, indicating that the shells had not been rolled about much. A 
study of the exposures on Big Pine Key shows that the shells as a rule 
are but slightly worn. All the fossils are living species. 
Areal Distribution:—The rock outcrops on the shores of Harbor 
Key and Content Key and on most of the Keys south and southwest. 
It underlies the Bay of Florida for at least three miles southeast of 
Big Bahia Honda Key and forms the surface of Boca Grande, ten 
miles west of Key West. 
ORIGIN OF FLORIDA OOLITES. 
The Miami and Key West oolites differ so slightly, the chief differ¬ 
ences being the greater percentage of quartz grains and stronger 
cross bedding near Miami, that they may be assumed to have had a 
common origin. Whether their origin was aeolian or whether it was 
marine is a point of interest. The evidence comprises the field rela¬ 
tions of the rocks, their appearance in outcrops and their lithologic 
and paleontologic characteristics. 
The oolites are presumably thin. At Dania they overlie “blue 
mud,” at Miami quartz sands and worn shell fragments cemented by 
clear crystalline calcite separated by layers of sand containing nodules 
of quartz grains; at Key West the oolite aparently overlies a shallow- 
water lime-sand rock. Nowhere has the Miami oolite been proved to 
rest on an old coral reef. 
Outcrops of oolite are not known north of Delray, on the east 
coast, nor anywhere on the west coast. While exposures form con¬ 
spicuous bluffs near Miami and low ridges for a few miles west, yet 
much of the Miami oolite is flat topped, outcrops showing differences 
of less than five feet in elevation for miles toward Long Key. Long 
Key itself is nowhere ten feet above sea level. Nowhere on the main¬ 
land are ridges comparable with the siliceous sand ridge at Hobe 
Sound. The flat smooth tops of the oolite exposures in the keys west 
of Bahia Honda are one of their most striking features. 
The cross-bedding of the oolite is more marked in some outcrops 
than in others; in some the cross-bedding is not at all conspicuous, 
the best cross-bedding is near the ocean or Strait of Florida rather 
than inland. The writer believes the cross-bedding is that of water- 
laid material; he can not see that it is like that of the wind-borne sands 
in the dunes at Cape Henry, Virginia. 
The oolite is abundantly fossiliferous, in places containing delicate 
shells with valves adherent, in places shells of some size and heavy 
