188 Davis — Dana's Confirmation of Darwin's Theory. 



in reaching a decision seems hardly necessary. The alterna- 

 tive theories of outward growth on still-standing islands, of 

 veneering barrier reefs on sea-cut platforms, and of upward 

 growth on up-built submarine banks, certainly deserve to be 

 considered wherever they can find application. The down- 

 wearing of uplifted reefs and atolls is evidently pertinent in 

 certain cases of complicated history. Every case must, as 

 Agassiz repeatedly insisted, be independently investigated. 

 Nevertheless, it may now be fairly said that the theory of sub- 

 sidence deserves for a number of well studied examples the 

 acceptance that it long enjoyed, and that it for a time and in 

 part lost. It affords not merely a possible explanation ; it 

 exposes a well-supported explanation of many barrier reefs, 

 and hence probably also of many atolls. The postulate of 

 subsidence, on which Darwin's theory is based, is justified and 

 established by the independent evidence brought forward by 

 Dana. 



