1 24 THEORY OF THE FORMATION Ch. V. 



of one or two hundred feet. So highly improbable is 

 this supposition, that we are compelled to believe, that 

 the rocky foundations of the many atolls did never at 

 any one period all lie submerged within the depth of a 

 few fathoms beneath the surface, but that they were 

 brought into the requisite position or level, some at one 

 period and some at another, through movements in the 

 earth's crust. But this could not have been effected 

 by elevation ; for the belief that points so numerous and 

 so widely-separated were successively uplifted to a cer- 

 tain level, but that not one point was raised above that 

 level, is quite as improbable as the former supposition, 

 and indeed differs little from it. It will probably occur 

 to those who have read Ehrenberg's account of the reefs 

 of the Eed Sea, that many points in these great areas 

 may have been elevated, but that as soon as raised, the 

 protuberant parts were cut off by the destroying action 

 of the waves : a moment's reflection, however, on the 

 basin-like form of the atolls, will show that this is 

 impossible ; for the upheaval and subsequent abrasion 

 of an island would leave a flat disk, which might become 

 coated with coral, but not a deeply concave surface ; 

 moreover, we should expect to see, at least in some 

 parts, the rock of the foundation brought to the surface. 

 If, then, the foundations of the many atolls were not 

 uplifted into the requisite position, they must of neces- 

 sity have subsided into it ; and this at once solves every 

 difficulty, 1 for we may safely infer from the facts given 



1 The additional difficulty on the crater hypothesis before alluded to, 

 will now be evident ; for on this view the volcanic action must be sup- 



