Ch. V. OF COKAL-KEEFS. 141 



by the accumulation of sediment. But during the 

 action of such nicely balanced forces, it would be strange 

 if the currents of the sea had never made a direct 

 passage across some of these atolls, through the many 

 wide breaches in their margins. As soon as this occurred 

 the channels would be deepened by the removal of the 

 finer sediment, and by the check to its further accumu- 

 lation. The sides also of the channels would soon be 

 worn into a slope like that on the outer coasts, from 

 being exposed to the same force of the currents. In 

 fact, a channel like that bifurcating one which divides 

 Mahlos Mahdoo (Plate II. fig. 4) would almost neces- 

 sarily be formed. The scattered reefs situated near the 

 borders of the new channel, from being favourably 

 placed for the growth of coral, would, by their exten- 

 sion, tend to produce fresh margins to the dissevered 

 portions : and a tendency of this kind is evident in the 

 elongated reefs which border the two channels inter- 

 secting Mahlos Mahdoo. Such channels would become 

 deeper with continued subsidence, and, from the reefs 

 on both sides not growing up perpendicularly, some- 

 what broader. In this case, and more especially if the 

 channels had been originally formed of considerable 

 breadth, the dissevered portions would soon become per- 

 fect and distinct atolls like Ari and Eoss atolls (Plate II. 

 fig. 6), or like the two Mllandoo atolls, which must be 

 considered as distinct, although plainly related to each 

 other in form and position, and separated only by mode- 

 rately deep channels. Further subsidence would render 

 such channels unfathomable, and the dissevered portions 



