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



•unconformities of certain slightly elevated fringing reefs on the pro- 

 foundly eroded older (western) volcanic mass in the Oahu doublet, of 

 the fringing reefs in the lagoon of the barrier reef that surrounds the 

 skeleton island of Borabora in the Society group, and of the fringing 

 reefs along the greatly degraded lowlands along the southwestern side of 

 New Caledonia and along the Queensland coast inside of the Great 

 Barrier reef of Australia — these and many other similar unconformities 

 stand incontestably for Darwin's theory. 



DARWIN ON FRINGING REEFS 



The testimony of fringing reefs thus appears to be in most cases the 

 very opposite of that usually credited to them. It has been noted above 



Figure 9. — Submerged harrier Reef and a fringing Reef of a new Generation 



that Darwin regarded most fringing reefs as formed on rising coasts; it 

 is not generally understood that he also perceived that they might be 

 formed on subsiding coasts, where the subsidence has been so rapid and 

 so great as to drown any preexisteiit reefs. The statement of the young 

 naturalist on this point is brief but explicit: "If during the prolonged 

 subsidence of a shore, coral reefs grev^ for the first time on it, or if an 

 old barrier reef were destroyed and submerged, and new reefs became 

 attached to the land, these would necessarily at first belong to the fring- 

 ing class" (1842, 124). It is to be regretted that this passage has not 

 been more frequently quoted. The point of it has been independently 

 stated by Chanterac (1875, 635), but by no other author I have read. 



