Fig. 23.19. Coral reefs: fringing, barrier, and atoll reefs. A, a barrier reef in 

 the Caroline Islands, Polynesia; the land is crosshatched. B, an atoll in the Chagos 

 Archipelago, Indian Ocean. C, profile of a fringing reef. Living coral cannot survive 

 more than brief exposures to the air and usually does not grow above the low water 

 line. D, profile of a barrier reef (see Fig. 23.20, corals of a barrier reef). E, profile 

 of an atoll reef. Taken in a different place the section might have gone through 

 another island like the one included. {A and B from Principles of Geology by 

 Gilluly, Waters, and Woodford. Copyright, 1952. W. H. Freeman and Company. 

 C, D, and E, courtesy, McCurdy: Manual of Coastal Delineation. Washington, 

 Hydrographic Office, 1947.) 



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