W. M. Davis — Shaler Memorial Study of Coral Reefs. 253 



should have been formed on a submerging foundation. The 

 first submergence and the following emergence may therefore 

 have been of greater measure than the present altitude of the 

 elevated reef. It is important to note, as above stated, that 

 this series of submergences and emergences is not recorded on 

 all the neighboring members of the Fiji group : the island of 

 Mango, only twenty miles away to the southwest, has emerged 

 so recently that its elevated reef is very little dissected ; and 

 any submergence that it has since suffered has hardly sufficed 

 to separate its new fringing reef from the present shoreline 

 at the base of the undissected elevated reef ; hence, as Agassiz 

 repeatedly insisted, each island must be studied for itself. In 

 view of the local nature of these repeated changes of level, it 

 seems advisable to regard them as due to local movements of 

 the islands concerned, and it would therefore be permissible to 

 speak of them in terms of subsidence and uplift rather than in 

 terms of submergence and emergence, as has here been done, 

 in order not to exclude changes of sea level around a still- 

 standing island ; for, as will be shown more fully below, the 

 latter supposition places too much responsibility on the rest 

 of the world in accounting for local phenomena. It should 

 not, however, be forgotten that the prime element in the 

 explanation of the elevated reef of Yanua Mbalavu — namely, 

 its unconformable relation to the volcanic foundation — is not 

 certified by detailed observation of contacts, but only inferred 

 from a general view of the two masses. Further study on the 

 ground is much needed here. 



Elevated Fringing Reefs in the New Hebrides. — Mawson's 

 account of the New Hebrides islands* shows that elevated 

 reefs are found on nearly all of them. They are particularly 

 abundant on Efate, where they commonly rest upon horizon- 

 tally stratified " soapstones," presumably formed of decomposed 

 volcanic ashes and dust, and containing, according to Mawson, 

 various pelagic organisms which indicate deposition below sea 

 level. The reefs are usually in the form of benches or ter- 

 races of moderate width, and hence belonged when formed to 

 the class of fringing reefs. They now stand at various alti- 

 tudes up to 1000 or 2000 feet, and seem to be nearly horizon- 

 tal : hence it has been concluded for these reefs, as for many 

 others similarly situated, that they were formed during pauses 

 in the emergence to which their present altitude with respect 

 to sea level is due. 



This conclusion is by no means imperative for the elevated 

 reefs of Efate, in view of their conspicuously unconformable 

 relation to the soapstones on which they lie. The unconform- 



* D. Mawson, " The Geology of the New Hebrides," Proc. Linn. Soc. N. 

 S. W., 400-485, 1905. 



