BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 29, pp. 489-574 SEPTEMBER 30, 1918 



SUBSIDENCE OF EEEF-ENCIRCLED ISLANDS ^ 



BY W. M. DAVIS 



{Presented before the Society December 27, 1917) 



CONTENTS. 



Page 



Darwin's verifications of the theory of subsidence 490 



Unexplained confusion replaced by reasonable order 490 



Accordant distribution of different kinds of reefs 491 



Deep lagoons inclosed by barrier reefs 491 



Abandonment of the theory of subsidence 492 



Nine verifications for subsidence 493 



Embayed shorelines 494 



Dana's confirmation of Darwin's theory 494 



Embayed shorelines and the Glacial -control theory 495 



The slope of reef foundations 498 



Depth of lagoons as a measure of thickness of reefs 498 



The submarine slope of reef -encircled islands 499 



Reefs do not usually rest on shallow platforms 501 



Facts and inferences from charts 502 



The evidence of Viti Levu, Tahiti, and Queensland 503 



Details concerning Fiji reefs 504 



Neglect of physiographic evidence 505 



Unconformable elevated reefs 506 



Neglect of geological evidence 506 



Unconformable elevated reefs in Fiji 507 



Elevated reefs may have been formed during subsidence 510 



Accounts of unconformable reef contacts 511 



Prevailing inattention to reef contacts 512 



Unconformable fringing reefs 512 



Many fringing reefs testify to subsidence 512 



Darwin on fringing reefs 514 



Fringing reefs of the Philippine Islands 515 



The Philippines and the Glacial-control theory 519 



The submerged platforms of the Philippines. 521 



Unconformable fringing reefs in Samoa 523 



Unconformable fringing reefs in the Solomon Islands 524 



Distribution of submarine banks 526 



Replacement of atolls by submarine banks near the Philippines 526 



1 Manuscript received by the Secretary of the Society February 4, 1918. 



(489) 



