252 THE INFLUENCE OF INANIMATE SDEKOUNDINGS. 



and my escort from Aibukit was too unfamiliar with the route, 

 which is said to be not without danger, for me to undertake it 

 without any other guide. 



I believe that we may unhesitatiagly include these last- 

 mentioned reefs and islands with the Pelew group proper, as 

 belonging to the same system of elevations rising from the 

 bottom of the ocean — a system extending about eighty-five 

 miles from north to south, and measuring ten to fifteen miles at 

 its greatest width. I intentionally say a system of elevations, for 

 it seems to me quite impossible to suppose that this group of 

 islands and reefs can have been formed by a subsidence, as 

 Darwin's theory requires us to assume. To make this quite 

 clear, we will endeavour to account by the theory of subsidence 

 for the observed phenomena that I have described. , 



VII. The theory of subsidence as a means of explaining 

 the origin of the Pelew Islands. — If we suppose that the sub- 

 sidence has been equal everywhere throughout the group, as 

 must be allowed according to Darwin, it is, in the first place, 

 difficult to see why in the north only isolated atolls, in the 

 middle barrier-reefs, and in the south only fringing reefs, have 

 been formed ; and why, farther south still at Ngaur, all reef 

 structure should have almost ceased. According to the pre- 

 dominant views it is allowable to regard the depth of the reef 

 channel of Aibukit as a standard of measurement for the sub- 

 sidence that has taken place. This would thus amount at a 

 maximum to about fifty fathoms. Now if we imagine the 

 islands in the north to have been raised to a height exactly 

 corresponding to the actual amount of the assumed subsidence, 

 the bottom of the channel between Babelthuap and Kossol, as 

 well as .that between this atoll and Kriangle, must have been 

 in the highest degree favourable to the establishment of a growth 

 of corals. But this has not been the case ; on the contrary, 

 the channel to the north of Kossol is entirely free from them, 

 and that to the south more or leas so. If the form of the reef 

 were indeed due to subsidence only, the present fifty-fathom 

 line of soundings must coincide with the outline, at any rate 

 of the main features of the reef now existing ; the facts of the 

 case are precisely the contrary. Hence we must in the first 



