— 24 -^ 



// construction of tliose reefs. In all tlie islancls of coral , that 

 I) I have examined , tliere are unequivocal signs of their nnder- 

 //going dissolution by the action of the sea, that is to say, 

 //they have fornierly been elevated above the reach of the surf, 

 //and have, after the upper platforms of that elevation had 

 // been undermined and broken down by the action of the waves, 

 //been again elsvated, and the then uppermost platforms, again 

 // undermined , more or less , by the same action of the surf. 

 //I have observed coral blocks stauding on their smallest euds 

 // on the tops of reefs and low isles. To account for this po- 

 // sition of these blocks , it has been assumed that they have 

 // been throv/n up by the surf, but their position , height , and 

 //situation, are snch, as to utterly contradict that idea, and 

 // show that they have certainly formed parcs of an upper shelf, 

 // or platform , of which they are now the only reraains. It 

 //'ft'ould be utterly impossible for any waves, rising from the 

 //present level of the sea, to toss such great blocks to any dis- 

 //tance at the height whereat tliey are now standing, but even 

 //if that supposifcion were admissible, they coiüd not possibly 

 //have been placed, and then left by the sea, standing as they 

 // are , on their smaller ends , on the highest points of the reefs 

 // and isles." 



After thus stating the facts, with respect to those isles, and 

 vv'hich are also observable on the coral isles and reefs of this 

 (the Indian) ocean, and the Indonesian seas, captain "Wii.kes 

 gocs on to say that , // as all tlie coral isles lie on areas sub- 

 //jected to the efl'ects of volcanic action, we have no reason 

 //to doubt that they would be as liable to be upheaved and de- 

 //pressed by it, as those of unquestionably igneous origin. The- 

 //refore with so great and powerful an agent at hand, it seems 

 //to me that thcre is no necessity for resorting to a theory such 

 //as that of Mr. Dakwin's, inadequate of itself, and at variance 

 //with the facts observed." On this opinioii I have however 

 to remark that, whilst we know that some isles and reefs have 

 undoubtedly been upheaved, we have no authentic instances of 

 any having been depressed, and so Mr. Daiiwin''s theory is, as 



