KOLUMADULU. 123 



with coarse shingle. Towards the inner face it gradually passes into 

 smaller and finer shingle and finally into coral sand. The shingle points 

 are often connected by bars of small boulders or coarse shingle, forming 

 a belt or breakwater on the outer edge of the reef flat. Thus an outer 

 bay is formed, coarse sand is deposited behind the low dam of shingle, 

 a sand-bar soon rises well above the general level of the reef flat, scanty 

 vegetation begins to cover the summit of the bar, and then a crescent- 

 shaped or open rectangular island is formed ; it eventually becomes filled 

 with sand blown in both from the sea face and the lagoon side. The small 

 independent islands are thus gradually connected into larger ones, forming 

 perhaps even such a large island as Fahala. 



Some instructive stages of this process of consolidation of the islands 

 occur between Fahala and Diyageli (PL 66, fig. 2). In one of the gaps in the 

 immediate vicinity of Fahala rose a mere islet flanked with bushes and 

 sand-bars forming a bridge between the adjacent islands. The east face 

 of Kolumadulu recalls vividly the aspect of the outer rim flats of many 

 of the Marshall and Gilbert Atolls, where the islands form great square 

 bays, often becoming connected on the lagoon face after they have been 

 shut off from the sea by the long line of boulders and shingle forming the 

 breakwater connecting their sea face extremities. 



South of the eastern pass dividing the two narrow reef flats which flank 

 the east face of Kolumadulu extends a line of angular coral boulders 

 similar to that on the edge of the northern reef flat ; it must be at least 

 three quarters of a mile long and forms a boulder and shingle breakwater 

 on the outer edge of the reef flat connecting two of the islands upon the 

 outer part of the rim flat, distant at least three quarters of a mile. On the 

 inner edge of the rim flat rise sand banks, islets, or islands, more or less 

 covered with vegetation, gradually closing the open gap between the inner 

 extremities of the islands first united by the breakwater thrown up on the 

 outer face of the reef flat. One of these breakwaters connecting adjoining 

 islands enclosed a bay nearly two miles in length ; the inner face of the bay 

 was flanked by four small islands with sand spits extending from both 

 extremities nearly joining them. On the islands of the east face of Kolu- 

 madulu we noticed many Pandanus trees. 



