326 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



geology of the Fiji Islands, where "since the Pleistocene period the 

 algebraic sum of the movements has been positive and uphft has 

 resulted." ^ Very many similar instances, the Bermudas, the Bahamas, 

 Florida, and Cuba among them, can be given. The criticisms of the 

 Darwin-Dana hypothesis apply to the recent publications of W. M. 

 Davis. 



2. Semper, Alexander Agassiz, and others, who have maintained 

 that barrier coral reefs have formed in areas of uplift, are correct, it' 

 the sum total of the movements since some date back in Tertiary 

 time be considered, and their observations and deductions are valu- 

 able in that they emphasize these facts; but they are in error in that 

 they failed to take into account that in many areas there is incon- 

 trovertible evidence showing submergence of the basements of the 

 now-living reefs. Semper made astute observations on currents, but 

 his deductions as to the formation of lagoons by destructional proc- 

 esses are not warranted. 



3. Sir John Murray invented a very stimulating hypothesis, and 

 correctly emphasized the necessity of taking submarine planation 

 into account m studies of the basements of coral reefs. He, however, 

 overlooked important facts clearly proving Recent submergence in 

 coral-reef areas, and his theory of the formation of atoll lagoons and 

 lagoon channels through submarine solution by sea water is enthely 

 disproved, and there are no other known destructional processes 

 whereby lagoons may be formed, for lagoons are areas of sedimentation 

 in which filling predominates over removal of material. 



4. Guppy is correct in his interpreta,tion of offshore reefs bemg 

 superposed on submarine platforms or "ledges," and he m.ade nu- 

 merous valuable contributions to our knowledge of coral reefs, but he 

 failed to take into account evidence showing Recent submergence. 



5. Admiral Sir W. J. L. Wharton made one of the greatest con- 

 tributions to om' knowledge of atolls when he discovered the flatness 

 of the floors and the uniformity of depth in atoll lagoons, and he 

 pointed out the inadequacy of the Darwinian hypothesis to explain 

 these phenomena. He emphasized the importance of submarine 

 planation in leveling the top of peaks that reach or almost reach sea 

 level, and definitely suggested the supe^'position of coral patches and 

 atoll rims on flats produced in that way. He not only did not oppose 

 the subsidence of such flats, but he thought that they frequently do 

 "subside and that some of the deeper lagoons may owe their depths of 

 50 fathoms or so to such a movement, quite apart from subsidence 

 of large areas which we know occiu's." The only emendations of these 

 statements that I can suggest is that the probable effects of glacia- 

 tion and deglaciation might have been considered. 



1 Nat. Acad. Sci. Proc, vol. 7, p. 309^ 1917. 



