On Areas of Subsidence in the Pacific. 311 



east coast of America ; while in mid-ocean it is at least fifty- 

 six degrees wide, and about sixty-four degrees on the cast 

 coast of Asia and New Holland. The peculiar bend of the 

 east coast of South America carries oiF to the northward much 

 of the usual south intratropical current, and it is therefore less 

 distinct in its effects than the northern intratropical or Gulf 

 Stream. 



We have hence the remarkable fact, that the coral zone is 

 fifty degrees wider on the eastern than on the western coasts 

 of our continents. Such is the effect of the ocean currents in 

 limiting the distribution of marine animals. These facts will 

 be brought out more fully in the reports of the Exploring Expe- 

 dition. The important bearing of these facts upon the distri- 

 bution of fossil species is too apparent to require more than a 

 passing remark. The many anomalies which have called out 

 speculations as to our globe's passing through areas in space of 

 unequal temperatures, are explained without such an hypo- 

 thesis. Instead of looking to space for a cause, we need not 

 extend our vision beyond the coasts of our continents. — Ame- 

 rican Journal of Science and Arts, vol. xlv., No. I. p. 130., 

 July 1843. 



On the Areas of Subsidence in the Pacific, as indicated by the 

 Distribution of Coral Islands. By James D. Dana, Geologist 

 of the United States Exploring Expedition. Head before 

 the Association of American Geologists and Naturalists, at 

 Albany, April 29, 1843. 



The theory of Mr Darwin, with regard to the formation of 

 atolls, or annular coral islands, has been fully confirmed by the 

 investigations of the Exploring Expedition ; but his regions of 

 subsidence and elevation, and the conclusion that these changes 

 are now in progress, appear to have been deduced without suf- 

 ficient examination. Observations at a single point of time 

 cannot determine whether such changes are in progress ; they 

 can only assure us with regard to the past. A series of exa- 

 minations, for years in succession, is necessary to enable us to 



