xvi INTRODUCTION. 



such clusters of atolls as those of North and South Male, of Ari, of Malos- 

 madulu, and of other groups, their arrangement is such as to form well- 

 defined rims, reminding us of the rims formed by great reef flats such as 

 are common in the Pacific. 



In such groups of atolls as Miladummadulu and its Tiladummati extension 

 we have the key to a rational explanation of the formation of the atolls and 

 groups of atolls in the Maldives. The two atolls I have just named are not 

 atolls in any sense of the word. They are so ill-defined that their division 

 for political purposes is marked on the chart by a mere dotted line. In fact, 

 they are composed of a great number of small atolls, often separated by con- 

 siderable distances, as much as five to ten miles, which have gradually grown 

 up on that part of the Maldivian plateau from depths of twenty-five to thirty 

 fathoms, and where they can be seen in all possible stages of growth. 



The shape of the rings (faros) or bars or flats is not necessarily circular ; it 

 varies greatly and is indirectly controlled by the topography of the bottom. 

 Some of the faros are elliptical, pear-shaped, or crescent-shaped, differing 

 greatly in outline and dimensions on the outer lines of the composite atolls. 

 Their outer slopes are covered with corals growing with great luxuriance 

 from the edge or even from the surface of the flats of the ring to a depth of 

 from eight to twelve or fifteen fathoms. The superb growth of corals found 

 in all the lagoons of the Maldives is in marked contrast with the scanty 

 growth of corals in the lagoons of the atolls of the Pacific. We have a 

 simple explanation of this in the fact that the rim of the atolls in the 

 Maldives is full of wide and deep passages. In fact, the extent of the 

 passes is generally much larger than the space occupied by the small atolls 

 (the atollons or faros) and reef flats. 



As soon as the rim flats of the rings have reached the surface, either 

 wholly or in part, sand-bars begin to form ; these develop rapidly into islets, 

 and finally into large islands more or less covered with scrub vegetation and 

 bushes. The rings or faros either retain a central lagoon or it becomes 

 partly or wholly filled up. In the former case they appear as small atolls 

 with islands or islets on the reef flats ; in the next stage there is either a 

 smaller lagoon on the lee face of a larger island, or else the island has grown 

 to occupy the whole flat of the faro with only very narrow flats on the 



