264 THE INFLUENCE OF INANIMATE SUEEOUNDINGS. 



passed into the present condition of very slow elevation or 

 absolute rest without any conspicuous break. 



Au attempt to explain the structure of the reefs of the 

 Pelew Islands. — I have said that the theory of subsidence is 

 insuificient to explain the sections given on p. 258, since, according 

 to that theory, on the steep west coast there ought to be a fringing 

 reef, and on the shelving east coast a barrier reef. Exactly the 

 contrary is the case. The occurrence of shallows without reefs 

 close to atolls, as at Kossol, and of high reefless islands, as 

 Ngaur, the high blocks on the west side and outer edge of 

 all the western reefs, the extensive, almost horizontal, sub- 

 marine level to the north of Pelelew, the uninterrupted connec- 

 tion of the eastern reefs of Pelelew and Kriangle with the 

 dead raised coralline cliffs — all these facts are arguments, hardly 

 to be refuted, against a recent subsidence. And if all of these 

 should be explained away by arbitraiy assumptions of which 

 the baselessness could only be proved by fresh investigations 

 carried out on the spot, we still should be obliged to accept the 

 degrading action of the movement of the sea, and, above all, 

 that of constant currents, as causes co-operating with the 

 supposed subsidence. I, of course, readily admit that these 

 must have had their effect, but I positively dispute that the 

 recognition of these effects proves the necessity of a subsi- 

 dence. On the contrary, I believe that those apparently 

 secondary causes would be far more likely to be effective during 

 a period of elevation than when combined with subsidence, and 

 that all the conditions I have described which argue against 

 a subsidence under the other hypothesis may be perfectly ex- 

 plained by easy and independent assumptions. This, in the first 

 instance, applies of course only to the structure of the Pelew 

 reef, and it must remain for further investigations to determine 

 how far similar conditions may exist or not in other coral 

 islands ; since the proof that here, in the Pelew Islands, subsi- 

 dence cannot have been the special cause which has determined 

 the form of the reefs is, self-evidently, no proof that in other 

 groups subsidence may not have been combined with the 

 upward growth of the reef in the form impressed on it by other 



