272 THE INFLUENCE OF INANIMATE SUEEOUNDINGS. 



it is said, reef-building corals can exist. Kay, it even may pos- 

 sibly be said that my explanation as regards the Pelew reefs 

 deserves no further attention, for the very reason that it ignores 

 these fundamental facts, which lie at the root of the subsidence 

 theory. I admit that I have, up to this moment, left them out 

 of the question, but I have done so on purpose ; and I must 

 expressly contend that neither of these hypotheses deserves to 

 be introdxiced into the discussion, fur neither of them has been 

 established as a fact by investigation, but is merely inferred 

 from ill-founded observations. 



With reference to the first point — the great thickness of the 

 reef — I must confess that the method of estimating it as set 

 forth by Darwin and Dana does not appear to me in any way 

 to establish the conclusions arrived at. Both calculate by the 

 same method, but with very different results; they agree in 

 estimating the thickness of the reef on the arbitrary hypothesis 

 that the foundation on which the submarine base of the reef 

 rests, must have the same inclination as is visible to observation in 

 the islands enclosed by the reef Dana indeed assumed a some- 

 what less steep incline than Darwin ; but it is quite possible, if 

 not probable, that even Dana allows a too great incline for the 

 submarine fall of the coast ; for we know that even in regular 

 cones the base usually exhibits a more gradual slope than the 

 peak, and according to the subsidence theory it can only be the 

 peaks of the mountains that rise above the surface of the sea ; 

 hence the base, which is covered by the reef, must probably have 

 a much less steep incline than can here come under our direct 

 observation. Thus, under all circumstances, the calculated 

 thickness of the reef remains hypothetical, since it is founded on 

 an assumption which is unproved by observation. Hence, so 

 long as it is not demonstrated by borings that the reef is in fact 

 as thick at its outer edge as has been estimated from the angle 

 of inclination of the land suiTounded by it, this estimated thick- 

 ness cannot be regarded as an available ai-giiment for any further 

 conclusions. 



If these assertions as to the depth of the reef were actu- 

 ally correct, it would inevitably follow — from the fact, which 

 hardly admits of dispute, that the reef-forming species of coral 



