32 vaughan: geologic history of coral reefs 



to that indicated for the West Indies. E. C. Andrews and C. 

 Elschner have both described warping and tilting, the former for 

 the Fijis, the latter for the Pacific more or less in general. Agas- 

 siz described an elevated atoll Makatea, in the Paumotus; and 

 Andrews has given a detailed description of the elevated atoll of 

 IMango, Fijis. Because of the differential nature of the earth 

 movements, in certain places old atolls have been uplifted to 

 heights as great as 230 feet in Makatea, and 600 feet in Tuvutha, 

 Fijis; while other old atolls, such as Rangiroa and others in the 

 Paumotus, now stand at or near sea level. In other areas there 

 has been depression, Bora Bora for instance, as Dana, P. Mar- 

 shall, and more recently W. M. Davis, have shown. Systematic, 

 detailed studies of the relations of the Recent to the older reefs, 

 with special reference to oscillation of sea level and differential 

 crustal movement in Pleistocene time, are among the desiderata 

 in the investigation of coral reefs. 



barrier reef platforms 



It has already been stated that the existence of the platform 

 on which the Recent barrier reef of Florida stands is independent 

 of the reefs, as it is continuous irrespective of the geographic 

 limits of the reefs. A similar statement may be made regarding 

 the Bahamas and Cuba, where in each instance the platform is 

 independent of the reefs which merely grow upon its surface 

 where conditions are favorable for the life of corals. E. C. An- 

 drews in 1902 remarked regarding the platform of the Great Bar- 

 rier Reef of Australia that ' ' the continuance in width of the shelf 

 southwards of the limits of reefs (coralline), and the great shoals 

 thereon, points to a minor part only of the shelf being formed of 

 coral growth." An inspection of the Admiralty charts for the 

 eastern coast of Australia shows conclusively that the platform 

 on which the Great Barrier Reef of Australia stands has an exist- 

 ence independent of the Great Barrier Reef, and that corals have 

 established themselves on this platform where the conditions 

 favorable for their life are realized. 



An examination of the barrier reef platforms of Florida, An- 

 dros Island, Bahamas, Cuba, and Australia, all lead to the same 



