492 W. M. DAVIS SUBSIDENCE OF REEF-ENCIRCLED ISLANDS 



dations ; and to this he added, rightly disregarding solution as a process 

 for the production of lagoons: "The existence, also, of the deep channel 

 utterly precludes the idea of the reef having grown outwards on a founda- 

 tion slowly formed on its outside by the accumulation of sediment and 

 coral detritus" (49). He noted, furthermore, that "a considerable degree 

 of relation subsists between the inclination of that part of the land which 

 is beneath water and that above it," and therefore constructed profiles in 

 which the visible slopes of high islands were prolonged beneath sealevel 

 as a means of determining the depth of barrier-reef foundations, and con- 

 cluded that "the vertical thickness of these barrier coral reefs is very 

 great" (47). But as this line of evidence was not closely discussed, it is 

 here further considered on a later page. 



ABAXDONMENT OF THE THEORY OF SUBSIDENCE 



It is true, however, that the theory of upgrowing reefs on intermittently 

 subsiding foundations did not gain a satisfying amount of independent 

 verification at Darwin's hands. The acceptance of the theory through 

 the middle of the nineteenth century as presenting the only possible 

 origin of coral reefs was based chiefly on the insufficient ground that it 

 explained the facts which it was invented to explain. Hence, when ap- 

 parently competent alternative theories were brought forward about 1880, 

 many former believers in Darwin^s theory lost confidence in it ; but, illog- 

 ically enough, they thereupon adopted one or another of the newer theo- 

 ries, although these were as little supported by independent verification 

 as Darwin's was. It was as if they said : "The peculiar features of coral 

 reefs, which we have hitherto thought could be explained only by Darwin's 

 theory of upgrowth on subsiding foundations, are now shown to be ex- 

 plicable by outgrowth from non-subsiding foundations. Subsidence is 

 therefore no longer a necessary condition of reef formation; hence subsi- 

 dence did not occur. We therefore abandon Darwin's theory and adopt 

 the newer theory." It would have been more reasonable to say: "Now 

 that two or more possible origins for coral reefs have been suggested, let 

 us seek means of critically determining which suggestion best represents 

 their actual origin." 



This course was seldom adopted. Thus Sir A. Geikie declared : "No 

 satisfactory proofs of a general subsidence have been obtained from the 

 region of coral reefs. ... In face of the evidence which has now been 

 accumulated, I can no longer regard the accepted theory [Darwin's] as 

 generally applicable" (1883, 27). Hahn stated: "So reiht sich Tatsache 

 an Tatsache um uns zu iiberzeugen, dass Darwin's Korallentheorie, an 

 der noch vor wenigen Jahren kaum jemand zu rutteln wagte, jetzt aufge- 



