342 On Areas of Subsidence in the Pacijic, 



arrive at the grand deduction, that the land in any part of our 

 globe is now undergoing a gradual change of elevation. The 

 views of Mr Darwin, respecting the rise of the South American 

 coast, as well as that of the Pacific and East Indies, may well 

 be received with some hesitation. According to my own obser- 

 vations, regions, in which his theory would require a subsi- 

 dence, have actually experienced an elevation at some recent 

 period. I might instance several examples of this elevation in 

 various parts of the Pacific. Suffice it to say here, that I found 

 nothing to support the principle laid down by him, that islands 

 with a barrier reef are subsiding, while those with only a 

 fringing reef are rising ; indeed, facts most stubbornly deny it. 

 Without entering upon the discussion of these facts, which, as 

 they will appear in the government publications, I am not at 

 liberty to dwell upon here. I propose to point out what are the 

 regions of subsidence which the coral islands in the Pacific in- 

 dicate as having been in progress during their formation. 



Before proceeding, I may be excused for adding here a few 

 words in explanation of Mr Darwin's theory, with regard to the 

 formation of coral islands. He rejects the unfounded hypo- 

 thesis that coral islands are built upon the craters of extinct 

 volcanoes, and proposes the following theory in its stead, which 

 is supported by a minute as well as general survey of the facts. 

 The coral belt or atoll, he supposes to have been originally a 

 barrier reef around a high island, like the reef round many is- 

 lands in the Pacific. When the reef commenced, it could not 

 have been extended to a lower depth than 100 or 120 feet, for 

 this is the limit of the reef forming corals. But if the island 

 gradually subsided — so gradually that the corals could by their 

 growth keep themselves at the surface, the reef might finally 

 attain any thickness, according to the extent of the subsidence. 

 In this manner, subsidence might finally submerge the whole . 

 island, and leave nothing but the reef at the surface. Mr 

 Darwin points to instances in which only the mountain tops 

 now remain above the ocean. Carry the process a little far- 

 ther, and we have the coral belt surrounding its little sea — the 

 usual condition of the coral island. 



This theory, as is seen, supposes extensive subsidence. And 

 so, we remark, must every theory ; for, without it, wo could 



