128 THE CORAL REEFS OE THE MALDIVES. 



reef flat is in the trend of the prevailing monsoons. Kolumadulu and 

 Haddunimati, though somewhat protected by the banks to the north, are 

 hke the northernmost atolls of the Maldives exposed both on the east and 

 west faces to the full action of the monsoons, while Suvadiva and Addu 

 are completely isolated from the banks to the north of them. 



The greatest depth of the northern part of Haddummati is forty-three 

 fathoms. The majority of the soundings in the central area are over thirty 

 fathoms. 



In the southern part of Haddummati are found a few sand-bars ; on the 

 whole, it is quite as clear of islands as most of the Pacific atolls. In the 

 lagoon of Haddummati we do not meet the many faros characteristic of 

 the northern Maldives. Haddummati belongs more to the type of a large 

 Pacific atoll than to a Maldivian group. The greatest length of Had- 

 dummati from north to south is twenty-six miles, its greatest breadth is 

 fifteen miles. 



On the western face the majority of the islands are on the southern 

 reef flat between Mavaru and Hitadu. The west face of Haddummati, 

 south of the northwest entrance, is flanked by two large reef flats, with 

 five islets on the southern one covered with low vegetation. No well- 

 defined lagoons are found on either of the flats. The outer rims are edged 

 with numberless patches of corals extending well over the reef flat. The 

 horn north of Munafuri pass is edged with a narrow belt of boulders. 

 The western faces of the islands are edged with small boulders or coarse 

 shingle passing into coral sand towards their eastern faces. Where there 

 are no i,slands, the edge of the reef flat is bordered by a belt of small 

 boulders. At low water the reef flats are awash. 



Somewhat south of Mavaru (PI. 67) a number of small islands run diag- 

 onally across the reef flat forming bays. The extremities on the sea face 

 are connected by a belt of boulders and shingle forming a low ridge be- 

 tween them ; it also gradually passes into coral sand towards the eastern 

 end of the islands. This belt of boulders is exposed to the full force of the 

 southwest monsoons. Further south the bays thus formed (PI. 67, fig. 2) 

 are closed on the eastern side by sand banks and islets or islands, covered 

 with low vegetation, thrown up on the eastern rim of the land rim flat. 



