Ch. V. OF COEAL-EEEFS. 123 



sea. This appears actually to have been the case in 

 some parts of the West Indian Sea. But in the form 

 and disposition of the groups of atolls, there is nothing 

 to countenance this notion ; and the assumption that 

 a number of immense piles of sediment have been 

 heaped on the floor of the great Pacific and Indian 

 Oceans in their central parts, far remote from land, 

 where the dark blue colour of the limpid water 

 bespeaks its purity, cannot for one moment be 

 admitted. 



The many widely scattered atolls must, therefore, 

 rest on rocky bases. But we cannot believe that a 

 broad mountain summit lies buried at the depth of 

 a few fathoms beneath every atoll, and nevertheless 

 that throughout the immense areas, above-named, not 

 one point of rock projects above the level of the sea. 

 For we may judge of mountains beneath the sea by 

 those on the land; and where can we find a single 

 chain, much less several such chains, many hundred 

 miles in length and of considerable breadth, with 

 broad summits attaining the same height, from within 

 120 to 180 feet ? Even if it be assumed without any 

 evidence that the reef-building corals can flourish at a 

 depth of 100 fathoms, yet the weight of the above 

 argument is but little diminished ; for it is very im- 

 probable, that as many submarine mountains, as there 

 are low islands in the several great and widely-separated 

 areas above-specified, should all rise within 600 feet of 

 the surface of the sea and not one above it, as that they 

 should be of the same height within the smaller limit 



