vaughan: geologic history of coral reefs 31 



been brought to its present position by subsidence. The barrier 

 reef of Andros Island, Bahamas, also occupies the outer edge of 

 a depressed platform. 



It has been shown by the Australians, Andrews, Hedley and 

 Taylor, and David, that the platform of the Great Barrier Reef 

 of AustraUa has been brought to its present position thru sub- 

 sidence apparently associated with extensive faulting along the 

 eastern Queensland coast. Therefore the Floridian, Cuban, 

 Bahaman, and Australian barrier reefs all have a similar relation 

 to change of sea level, as in each instance the platforms on which 

 they occur have been brought to their present position thru 

 subsidence. 



There is one important difference between the relations of the 

 Recent barrier reefs of Florida and Andros Island, Bahamas, and 

 those of Cuba. The oscillations of the strand line in Florida 

 and Andros Island have taken place without appreciable differ- 

 ential crustal movement, while in Cuba there was notable de- 

 formation antecedent to the last depression. The Pleistocene ter- 

 races rise in height toward the eastern end of Cuba in Oriente 

 Province where altitudes of about 600 feet are attained near Cape 

 Maisi. The terraces decline in height toward the west, and west 

 of the longitude of Manzanillo there is a slope from the north to 

 the south coast. In Barbados Pleistocene reefs extend to 1000 

 feet in elevation. 



COMPARISON OF WEST INDIAN WITH CENTRAL PACIFIC REEFS 



Alexander Agassiz discovered that in the Paumotuan atolls the 

 Recent corals were growing as a thin crust on an older limestone 

 foundation. His explanation of the formation of the atolls by 

 the destruction of the interior of a limestone mass must be dis- 

 carded. As there was evidently a period of atoll formation in 

 the Paumotus previous to the establishment of the Recent corals 

 the conditions there simulate those in the Tortugas, Florida. A 

 great developnent of Pleistocene and perhaps late Tertiary coral 

 reefs in the tropical Pacific has been proven in the most convinc- 

 ing manner, and there is abundant evidence of differential crustal 

 movement in the tropical Pacific in Pleistocene time similar 



