Crosby.] 480 [November 7, 



geological structure, essentially identical with the great island 

 continent. Although comprising both the older and newer strat- 

 ified formations, these islands are largely volcanic, and are bor- 

 dered by extensive fringing coral reefs. But they are properly a 

 part of the great Polynesian Archipelago, and differ from the 

 equally high, volcanic and coral-girt New Hebrides and Feejee 

 groups mainly in being larger and containing some Paleozoic and 

 Secondary rocks. And beyond the last named groups the islands 

 are still smaller and lower, and barrier reefs predominate, until 

 the volcanic heights entirely disappear and their sites are marked 

 only by atolls and coral islands. Still farther east and north the 

 subsidence becomes too great for even these, and the blank sea 

 alone remains. Thus the continental shade off insensibly into 

 oceanic conditions; and the same argument which makes the 

 larger islands of the Pacific portions of a submerged continent 

 applies with nearly equal force to the multitude of smaller 

 islands. 



In this connection it is interesting to consider what would be 

 the asj)ect of the continent of Asia after a subsidence of between 

 two and three miles. The great plateau of Thibet would still 

 have a considerable elevation above the sea, and, with its border- 

 ing mountain ranges, would compare in size with Australia. 

 While stretching away from it in all directions, especially to the 

 east and north, would appear long meandering lines of islands, 

 becoming smaller and lower with the distance. If the sea were 

 warm and the subsidence sufficiently gradual, the sites of the 

 lower mountains and ridges would be marked by monuments of 

 coral formation, and active volcanoes would also keep pace with 

 the subsidence. In short, modern Australasia and Polynesia 

 would be substantially reproduced. Hence it cannot be said that 

 there is anything in the topography of the Pacific islands militat- 

 ing against the idea that they are remants of a submerged conti- 

 nent. 



It is generally admitted that the West India islands are sub- 

 merged portions of the American continent ; in fact, the relations 

 of the fauna and flora to those of South and Central America 

 compel us to accept this conclusion. Yet these islands stand, for 

 the most part, in very deep water ; depths of from 10,000 to over 

 18,000 feet being common ; and the deepest holes being actually 



