ON CHANGES OF LEVEL IN THE PACIFIC OCEAN. 125 



inscribe their own history ; and there is a noble pleasure in deci- 

 phering even one sentence in this Book of Nature. 



From the actual extent of the coral reefs and islands, we know 

 that the whole amount of high land lost to the Pacific by the 

 subsidence, was at least fifty thousand square miles. But since 

 atolls are necessarily smaller than the land they cover, and the 

 more so, the farther subsidence has proceeded ; — since many lands 

 from their abrupt shores, or through volcanic agency must have 

 had no reefs about them, and have disappeared without a mark; 

 and others may have subsided too rapidly for the corals to retain 

 themselves at the surface ; it is obvious that this estimate is far 

 below the truth. It is apparent that in many cases, islands now 

 disjoined, have been once connected, and thus several atolls may 

 have been made about the heights of a single subsiding land of 

 large size. Such facts show farther error in the above estimate, 

 evincing that the scattered atolls and reefs do not tell half the 

 story. Why is it, also, that the Pacific islands are confined to 

 the tropics, if not that beyond thirty degrees the zoophyte could 

 not plant its growing registers? 



Yet we should beware of hastening to the conclusion that a 

 continent once occupied the place of the ocean, or a large part of 

 it, which is without proof. To establish the former existence of 

 a Pacific continent is an easy matter for the fancy ; but geology 

 knows nothing of it, nor even of its probability. 



The island of Banabe in the Caroline archipelago affords evi- 

 dence of a subsidence in progress, as my friend, Mr. Horatio Hale, 

 the Philologist of the Expedition, gathered from a foreigner who 

 had been for a while a resident on this island. Mr. Hale remarks, 

 after explaining the character of certain sacred structures of stone : 

 " It seems evident that the constructions at Ualan and Banabe are 

 of the same kind, and were built for the same purpose. It is 

 also clear that when the latter were raised, the islet on which they 

 stand was in a different condition from what it now is. For at 

 present they are actually in the water ; what were once paths, are 

 now passages for canoes, and as O'Connell [his informant] says, 

 1 when the walls are broken down the water enters the incis- 

 ures.' " Mr. Hale hence infers " that the land, or the whole 

 group of Banabe, and perhaps all the neighboring groups, have 

 undergone a slight depression." He also states respecting a small 

 islet near Ualan, "From the description given of Leilei, a change 

 of level of one or two feet would render it uninhabitable, and re- 

 duce it, in a short time, to the same state as the isle of ruins at 

 Banabe." 



Period of the subsidence. — The period during which these 

 changes were in progress, was probably since the tertiary epoch. 

 In the island of Metia, elevated over two hundred feet, the 

 corals below were the same as those now existing, as far as we 



