NORTH MALE. 



45 



The first ring we examined (PI. 13) was nearly circular, about half a mile 

 in diameter. It rose quite abruptly from a depth of nearly twelve fathoms 

 and sloped very gradually to the general level of the bottom of the greater 

 lagoon (thirty fathoms); the outer edge of the rim being about one hundred 

 and fifty feet from the vertical at the base of the rim slope. The width 

 of the rim varied from sixty to one hundred and seventy-five feet, the 

 general depth of the rim varying from two feet to two fathoms ; the slope 

 of the rim towards the interior of the enclosed lagoon was even steeper 

 than the outer slope. On the outer face corals grew in great profusion 

 from the very base to the edge of the rim and in patches on its surface. 

 The inner slope as well as the bottom of the lagoon consisted of coral 

 sand driven across the rim and gradually widening the eastern or western 

 rim according to the direction of the prevailing monsoon, the process at 

 the same time filling the central lagoon, which in this case was about 

 seven fathoms in depth. 



The corals were of the same genera as those growing on the island in 

 the southeast pass into North Male, and fully as luxuriant. We did not 

 observe any corals on the bottom of the small lagoon ; they must be killed 

 by the inflowing sand. A few patches of corals extend from the outer 

 base of the ring into somewhat deeper water, but they fast disappear and 

 the slope consists again of fragments of coral and coral sand. Towards 

 the northeastern face of the rim flat the sea breaks, the depth of a part 

 of the rim not being more than a few inches below the surface. The sand 

 of that part of the rim is kept greatly agitated, and we should expect 

 there the early formation of a sand-bar or diminutive islet on the rim flat 

 of the ring. 



The next faro we examined represented a stage in the formation of an 

 island considerably more advanced than that of the simple ring rim enclos- 

 ing a comparatively deep lagoon. It consisted of an extensive elliptical 

 flat (PI. 15, fig. 1) with but three or four feet of water at low tide, its rim 

 flanked on the east by a small narrow island covered with bushes rising 

 from a steep coral sand beach ; towards the west a small shallow lagoon, 

 judging from the color of the water, occupies a part of the reef flat. 



It seems a simple process to follow the transition of the first ring we 



