132 THE CORAL REEFS OF THE MALDIVES. 



partially closed by sand-bars and islets, thrown up from the west across the 

 gaps separating the islands forming the sides of the bays. The eastern 

 points of these islands often extend into the boulder belt ; they are gen- 

 erally flanked with boulders; these pass into shingle beaches and sand 

 beaches towards the lagoon face of the reef flats. The outer spit of an 

 island to the north of Karaidu is covered by such a mass of boulders ; 

 many of them are undercut, pitted, and honeycombed. To the north of 

 Mandu a narrow pass with eight fathoms of water leads into Haddummati. 



The northeastern horn of Haddummati is a great triangular reef flat 

 more than five miles in length and four across its base. The extremity of 

 the horn is occupied by Isdu (PI. 70), a large island nearly three miles in 

 length and steep to on the northern face. The chart shows a wide reef flat 

 surrounding Isdu, but from the position of the island it has evidently en- 

 croached on the flat, especially at the eastern extremity, so that its beaches 

 have become the outer edge of the reef flat. The great triangular horn of 

 Haddummati is full of sand-bars, and a number of small lagoons are en- 

 closed within the flat with from four to six fathoms of water. From Isdu to 

 Waduni Pass, a distance of nearly fifteen miles, only one small island occu- 

 pied the edge of the flat of the north side. A wide boulder belt extends 

 along the sea face of the eastern edge of the reef flat. North of Mabadu 

 Pass are ten small islands south of Dambidu, generally placed at an angle 

 with the trend of the sea face ; their beaches are usually composed of 

 coarse coral shingle, passing into finer shingle and sand towards the west. 

 The gaps between these islands are narrow, almost choked with lines or 

 jetties of coarse shingle or small coral boulders, leaving but the merest 

 narrow and shallow channels between many of them. Horses of eroded 

 coral reef rock, undercut, pitted, and greatly weathered, extend from the 

 boulder belt to the roots of the trees on the top of the beaches, showing- 

 traces of a slight former elevation of the reef flat. 



Looking north across the great triangular eastern reef flat, through one 

 of the gaps (PI. 69, fig. 2), one can see its northern edge dimly indicated 

 by an occasional sand-bar; seen through the gap between Dambidu and 

 Isdu its edge is marked by the small well-wooded islet which rises imme- 

 diately to the west of Isdu. The northern edge is also indicated by a thin 



