CORALS AND CORAL REEFS — VAUGHAN. 



237 



SOUTHEAST COAST OF ANTIGUA 



great development of coral reefs at the present time. However, I 

 am not in agreement with Daly in attributing so much work to 

 marine abrasion while the level of the sea was lowered during Pleis- 

 tocene time. It seems to me that most of the platforms are of pre- 

 Pleistocene age, and were wave-cut and remodeled around their 

 edges during Pleistocene time ; but this is a subject that needs much 

 more investigation. 



It should be stated that the raising of ocean level because of de- 

 glaciation will not explain the formation of all coral reefs, for in 

 places, as in some 



... 'FFF-T 



of the Fiji Islands, 

 according to W. G. 

 Foye, 1 the submer- 

 gence of the reef 

 basements is due to 

 the tilting of pre- 

 viously flat-lying 

 areas, on the sub- 

 merged part of 

 which reefs have 

 formed after the 

 tilting. In other 

 areas there is clear 

 evidence of tilting 

 and warping as in 

 the Bahamas and 

 Florida. General 

 submergence because of deglaciation is concomitant with local crustal 

 deformation. How the submergence produced is, as regards corals, 

 unimportant, provided there be gradual submergence of moderate 

 amount. 



CONCLUSIONS. 



The following are my conclusions on the formation of coral reefs : 



(1) Fringing reefs seem uniformly to have uncomformable basal 

 contacts; they may form after submergence that is not followed by 

 uplift or they may form during intermittent uplift that follows 

 submergence — that is, they may form during either emergence or 

 submergence. 



(2) Offshore coral reefs, barriers and atolls, form on antecedent 

 flattish basements during and after submergence in areas where the 

 general ecologic conditions suitable for reef-coral growth prevail, as 

 stated on page 215. This generalization applies to fossil as well as 

 to living reefs. 



NORTH COAST OF 

 ST. THOMAS 



< io7o n. *■ 



HAVANA HARBOR 

 showing depth of filled 

 channel in harbor 



■* 63 m/. >• 



MOSQUITO BANK 



Fig. 16.- 



-SlJBMARINE PROFILES OFF WEST INDIAN ISLANDS 

 AND ACROSS MOSQUITO BANK. 



1 The geology of the Fiji Islands 

 1917. 



Acad. Nat. Sci. Proc, vol. 3, pp. 305-310, April, 



