ARTICLES 433 



difficult to understand why the islands on which atolls were 

 to be formed should stand still for a long time before atoll 

 formation began ; but, like nearly all other students of the 

 coral-reef problem, Wharton took no account of these aspects' 

 of the problem. 



However, it is, I believe, possible that a still-standing 

 volcanic island should, after its eruptive construction, be cut 

 away by ocean waves, because no reefs can be formed on the 

 beach of loose detritus that would surround such an island 

 while abrasion is in progress * ; but it would require an enor- 

 mously long period of undisturbed abrasion to produce a plat- 

 form for a large atoll and especially to reduce its central part 

 to a depth of thirty or more fathoms ; and so long a period of 

 stability seems unreasonable, in view of the testimony of barrier- 

 reef islands, as above indicated. Moreover, unless an abraded 

 platform were disturbed after it was formed it would probably 

 remain without reefs indefinitely. The Glacial-control theory, 

 as expounded by Daly, gives a more plausible explanation of 

 the smoothness and depth of atoll lagoon floors than is provided 

 by Wharton's hypothesis ; but, as above noted, there are serious 

 difficulties in the way of accepting any theory of still-standing 

 and truncated atoll foundations. 



Inadequate Treatment of the Coral-Reef Problem. — It is not 

 only the several investigators above-named who have over- 

 looked the geological evidence for the subsidence theory of 

 coral reefs that is provided by embayed shorelines and un- 

 conformable contacts. Nearly all other students of the problem 

 have been equally inattentive to its geological aspects, although 

 embayed shorelines and unconformable contacts are almost 

 immediately discoverable by observation as facts of occurrence 

 and are very readily detected by deduction as essential conse- 

 quences of the theory of subsidence. I have searched through 

 many articles by observers abroad and by students at home, 

 and it is very rarely the case that they mention these significant 

 structural features of fringing and barrier reefs, whether they 

 accept or reject Darwin's theory. 



Accounts of the Pelew Islands by Kubary ('73), Wichman 

 ('75), Friederichsen ('01), and Wiszwianski ('09), are silent on 

 this aspect of the problem ; so are the accounts of the Seychelles 

 by Coppinger of the Alert ('83), Keller ('98), Chun of the Valdivia 



1 "Clift Islands in the Coral Seas," Proc. Nat. Acad. Set. ii. 1916, 284-288. 



