FRINGING REEFS OF THE PHILIPPINES 515 



Fringing reefs thus formed may be described as of a new generation. 

 The dimensions of the embayments of the shore that they border may 

 indicate a greater submergence than would be inferred from the small 

 advance of the reefs from the shore; and this I found to be the case on 

 certain i^iembers of the New Hebrides group. The external talus of such 

 reefs as well as the reef proper may rest unconformably on a slope of 

 subaerial erosion, now submerged: they may be frequently associated 

 with drowned fringing or barrier reefs of earlier origin, as indicated in 

 figure 9. Unfortunately reefs of this kind received no further attention 

 from Darwin than the above statement, apparently because the records 

 available to him showed the frequent occurrence of elevated reefs or of 

 marine fossils on the slopes above fringing reefs and thus led him to 

 associate such reefs with areas of elevation ; but also because he did not 

 perceive that when fringing reefs lie unconformably on a surface of sub- 

 aerial erosion, as reefs of a new generation must, submergence should 

 have preceded or accompanied their formation, even if the submergence 

 had been preceded by elevation. Unfortunately, also, many other students 

 of coral reefs have overlooked the occurrence and the significance of the 

 structural relations between sealevel fringing reefs and their foundation, 

 as here indicated. 



FRINGING REEFS OF THE PHILIPPINE ISLANDS 



Unconformable fringing reefs of a new generation appear to character- 

 ize the shores of the Philippine Islands to a remarkable degree, while 

 barrier reefs and atolls are rare thereabouts, as may be learned from the 

 admirable charts recently issued by our Coast and Geodetic Survey; and 

 yet no one has, so far as I have read, perceived that the facts thus pre- 

 sented afford strong testimony for Darwin's theory of subsidence. The 

 manifestly unconformable contacts of the fringing reefs on the maturely 

 dissected and more or less embayed shores of in any members of the much 

 disturbed Philippine group, largely formed of non-volcanic rocks, demand 

 long continued erosion while the islands stood higher — in several cases 

 much higher — than now, and a correspondingly great, though by no means 

 uniform or universal, subsidence to bring them down to their present 

 position ; and this at so rapid a rate that preexistent reefs, if they existed, 

 were drowned, and at so recent a time that the fringing reefs on the 

 headlands and the deltas in the bay heads have not as a rule attained 

 great development. The west coast of Palawan, the southwesternmost 

 member of the Philippines, gives many striking illustrations of these 

 features, none more impressive than at Malampaya Sound, here shown 

 in figure 10, reduced from a part of Coast Survey chart 4^16. Joubin's 



