vaughan: virgin and leeward islands 



63 





spread to be explained by local crustal movement. The changes 

 in position of strand line here noted are more reasonably ex- 

 plained by a lowering of sea-level due to the withdrawal of 

 water in the Pleistocene ice epochs to form the great Continental 

 glaciers and the raising of sea-level after each epoch through 

 the melting of the glaciers, but the volume of evidence supplied 

 by this area is perhaps not large enough to justify a general 

 conclusion as to the relations of Re- 

 cent coral reef development to gla- 

 ciation and deglaciation. 



Figure • 5 is a map of Florida 

 showing the superposition of upper 

 Oligocene reef corals and coral reefs 

 on the Ocala limestone, which has 

 been traced under and beyond the 

 reefs by means of natural exposures 

 and numerous well borings. The 

 general geologic history of the 

 Floridian plateau has been especi- 

 ally considered by Vaughan 4 and by 

 Matson and Sanford. 5 A paper by 

 Vaughan and Shaw in which the 

 oscillations of the Florida reef tract 

 are discussed is also cited. 6 



A brief comparison will now be 

 made with the Great Barrier Reef 

 of Australia. Figure 6 presents pro- 

 files, all on the same horizontal and 



vertical scales, the latter about seventy times the former. The 

 uppermost profile, along a line running due east from Virginia 

 Beach, Virginia, is introduced for comparison with those of 

 the Continental Shelf and the Great Barrier Reef off the eastern 

 Queensland coast. The Australian profiles are based on the 



4 A contribution to the geologic history of the Floridian plateau. Carnegie 

 Inst, of Washington, Pub. 133, pp. 99-185, 15 pis. 1910. 



5 Geology and ground waters of Florida. U. S. Geol. Surv., Water-supply Paper 

 319. Pp. 445, 17 pis. 1913. 



6 Carnegie Inst, of Washington, Year Book No. 14, pp. 232-238. 1916. 



Fig. 5. Map of Florida show- 

 ing depth in feet below sea-level 

 to upper surface of the Ocala 

 limestone and the location of the 

 superposed upper Oligocene coral 

 reefs and reef corals. Oc = Ocala 

 limestone; Al. B. = fossil reef 

 corals or coral reefs in the Alum 

 Bluff formation; Ch = fossil reef 

 corals or coral reefs in the Chatta- 

 hoochee and Tampa formations. 



