1 84 CORAL-REEFS. 



bason or ring-like shape both of the marginal and central 

 reefs in the Maldiva atolls — the union of some atolls as 

 if by a ribbon — the apparent disseverment of others — and 

 the occurrence, in atolls as well as in barrier-reefs, of 

 portions of reef, and of the whole of some reefs, in a dead 

 and submerged state, but retaining the outline of living 

 reefs. Thus can be explained the existence of breaches 

 through barrier-reefs in front of valleys, though separated 

 from them by a wide space of deep water; thus, also, the 

 ordinary outline of groups of atolls and the relative forms 

 of the separate atolls one to another ; thus can be explained 

 the proxifnky of the two kinds of reefs formed during 

 subsidence, and their separation from the spaces where 

 fringing-reefs abound. On searching for other evidence 

 of the movements supposed by our theory, we find marks 

 of change in atolls and in barrier-reefs, and of subterranean 

 disturbances under them ; but from the nature of things, 

 it is scarcely possible to detect any direct proofs of sub- 

 sidence, although some appearances are strongly in favour 

 of it. On the fringed coasts, however, the presence of 

 sipraised marine bodies of a recent epoch, plainly show, 

 that these coasts, instead of having remained stationary, 

 which is all that can be directly inferred from our theory, 

 have generally been elevated. 



Finally, when the two great types of structure, namely 

 barrier-reefs and atolls on the one hand, and fringing-reefs 

 on the other, were laid down in colours on our map, a 

 magnificent and harmonious picture of the movements, 

 which the crust of the earth has within a late period under- 

 gone, is presented to us. We there see vast areas rising, 

 with volcanic matter every now and then bursting forth 

 through the vents or fissures with which they are traversed. 

 We see other wide spaces slowly sinking without any 



