METHOD OF FORMATION. 33Q 



SKETCH SECTION OF THE WESTERN END OF RAINE's ISLET. 



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a. Vegetable soil. b. Little cliff at edge of stone. 



c. Loose coral sand. d. Edge of reef. 



c. Tliese two lines represent high and low water level, the rise and fall being about 

 10 feet. 



The method of the formation of this island seems 

 to have been the following : — A pile of sand was 

 gradually accumulated near the west or lee side of 

 the reef by the sweeping and piling action of the wind 

 and sea. This, when it had been permanently heaped 

 above high water mark, became partially consoli- 

 dated into stone near its upper portion, by the action 

 of the rain water, which, dissolving some part of the 

 carbonate of lime, re-deposited it again as it sank 

 through the loose sand, and formed the little con- 

 cretionary grains which bind the mass together. 

 The lower part of the sand heap, that below high 

 water mark, has been less affected by this action, 

 probably because it was saturated by sea water. 

 Some cause* then stopped the accumulation of sand, 

 and the sea at high water washed away part of that 

 already formed, and eat into this soft stone, wearing 

 it into a little cliff about four or five feet high. 

 This little cliff or step is found all round the island 

 at the edge of the stone, except at some parts of the 

 eastern end. After that, sand was again accumu- 

 lated, forming the broad margin of loose drift sand 

 now surrounding the island, and protecting the stone 

 from any farther waste by the breakers. No part 



* Perhaps this cause may have been a slight depression. 

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