94 FOYE. 



crater rim. In each observed case, a foraminiferal deposit occurring 

 beneath elevated Hmestone rests on an eroded basement and gives no 

 evidence of having assisted in aggrading a submerged, volcanic mass 

 to the level of coral growth. Indeed, in only one instance, near Savu 

 Savu bay, Vanua Levu, was an uplifted reef found which rested on a 

 contemporaneous, submarine lava flow, and none was found resting 

 on benches which appeared to have been cut by submarine erosion. 



Only Darwin's theory postulates a subsiding basement eroded above 

 sea-level. But this theory is firmly based on the conception of pro- 

 gressive, though intermittent, subsidence of large segments of the 

 earth's crust. The elevated limestones of Fiji were deposited during 

 pre-Recent subsidence. Since the Pleistocene period, the algebraic 

 sum of the earth movements has been positive and uplift has resulted ; 

 although the sum, if reckoned from the early Tertiary, is negative and 

 the ultimate result has been subsidence. However, the present reefs 

 are dependent for their form upon Pleistocene and Recent movements. 

 Hence it cannot be said that the modern reefs of Fiji fully support 

 Darwin's theory, since their history is not expressed by the simple 

 succession of fringing reef, barrier reef and atoll. The history of 

 the older, elevated limestones more nearly coincides with Darwin's 

 theorv than does the historv of the modern reefs. 



SUMMARY OF THEORETICAL RESULTS. 



The writer's views concerning the origin of barrier reefs and atolls 

 may be summarized as follows: — 



1. The present coral reefs have been developed on surfaces which 

 have been formed, as Agassiz in principle held, by the integration of a 

 number of processes acting during several geological periods. These 

 processes arc, (a) atmospheric erosion, (b) wave-cutting, (c) sedimen- 

 tation, and (d) volcanic aggradation. 



2. There is no logical reason why a coral atoll, given the proper 

 submarine bench, should not have existed in pre-Glacial as well as in 

 post-Glacial time. 



3. It is demonstrated that the older coralliferous limestones of Fiji 

 developed on a subsiding basement of eroded volcanic rocks and 

 formed barrier reefs and atolls. Very few of the modern reefs have 

 been formed in a similar way. 



4. Certain atolls are now developing on basements of elevated 



