110 THE CORAL REEFS OF THE MALDIVES. 



In none of the groups of the Maldives do we find the great well-defined 

 reef platforms which are so characteristic a feature of the atolls of the 

 Pacific. There the islands have in many cases been cut out and denuded 

 from the higher parts of the underlying reef platforms, while in the Mal- 

 dives the islands have merely been washed up as coral sand and deposited by 

 the drift, the winds and waves, on the rims of the faros or of the diminutive 

 flats. The surface of these is not always made up of recent movable sand, 

 when corals have spread upon them, they have become covered by a recent 

 reef rock and with loose masses of corals cemented by Nullipores and 

 coral sand. 



South Nilandu. 



Plates 1, 5 ; 8 b, figs. IS, 17 ; 62, 63, 64, fig. 2; 78, fig. 2. 



In South Nilandu (PL 5) the western and eastern faces run north and 

 south ; the northern and southern faces are rounded ; its greatest length is 

 about twenty-two miles, and the width thirteen miles. 



The banks and faros of South Nilandu are fairly uniformly distributed 

 over the area of the group, although the larger faros and banks are situated 

 in the northern part. The outer land rim of South Nilandu is made up of 

 extensive faros and reef flats. The reef flat forming the southwest face of 

 the group is over twelve miles in length. 1 The entrances to the enclosed 

 basin of South Nilandu are deep and wide, several of them over two miles 

 across. Only a few islands occur on the southwest and northwest face of 

 South Nilandu, the principal islands and islets being on its east face ; there 



1 The Admiralty Chart of South Nilandu does not show any difference in the indistinct velu of the 

 southwestern reef Hat from that sketched by Mr. Gardiner on Figure 105, which has left, as he says, 

 "a series of isolated reef masses, parts of the original great breakwater." Mr. Gardiner says that the 

 changes he observed in both South and North Nilandu were merely local, and that within the lagoons no 

 changes in depths were found. 



The shoal indicated by Mr. Gardiner in the pass north of Maimbudu may be an outgrowth of the 

 reef flat, as are probably those he indicates south of Feartu in North Nilandu ; they are perhaps indi- 

 cated on the Admiralty Chart, only more to the westward. 



Mr. Gardiner * indicates a smaller number of new velus on the inner banks and on the outer lagoon 



reef flats of South Nilandu than in North Nilandu ; only one velu is added on one of the flats of the 



eastern face, while he notes changes in nearly all the lagoon reefs of the southern part of the east face 



of North Nilandu. 



* Loc. cit., fig. 105, p. 405. 



