Coral Reefs and Islands. 279 



form to suggest similarity of origin to the drift-made barriers 

 of sand. 



c. In the Pacific Ocean, the trends of many of the coral- 

 island groups and of the single islands do not correspond 

 with the direction of the oceanic currents, or with any eddy 

 currents except such as are local and are determined by them- 

 selves. 



Near longitude 180°, as the map of the Central Pacific (see 

 Part I.) illustrates, the equator is crossed by the long Gilbert 

 (or Kingsmill) group, at an angle with the meridian of 25° 

 to 30°, and not in the direction of the Pacific current, which 

 is approximately equatorial. This obliquely crossing chain of 

 atolls is continued northward in the Ratack and Ralick Groups 

 (or the Marshall Islands), making in all a chain over 1200 

 miles long ; and, adding the concordant Ellice Islands on the 

 south, and extending the Ratack line to Gaspar Rico, its 

 northern outlier, the chain is nearly 2000 miles long. Nothing 

 in the direction of the long range, excepting local shapings 

 of some of the points about the atolls, can be attributed to the 

 Pacific currents. Moreover, the diversified forms of the atolls 

 have no sufficient explanation in the drift process. 



d. Further, drifting by currents may make beaches and 

 inner channels whether subsidence is going on in the region 

 or not, and are not evidence forj or against] either a move- 

 ment downward or upward. Sandy Hook, the long sandy 

 point off the southern cape of New York harbour, has been 

 undergoing (as the U. S. Coast Survey has shown) an increase 

 in length, or rather variations in length, through the drifting 

 of sands by an outside and an inside current ; and this is no 

 evidence that Professor G. H. Cook is wrong in his conclusion 

 that the New Jersey coast is slowly subsiding. 



e. But even in this region of Florida we have strong evidence 

 of a great subsidence during the coral-reef era, and all the 

 subsidence that the Darwinian theory demands. 



In a very valuable paper by Mr. Agassiz, published in 1879 

 in the Bulletin of the Museum of Comparative Zoology *, the 

 author points out that the South American continent, in com- 

 paratively recent geological times, had connection with the 

 West-India Islands through two lines : (1) one along a belt 

 from the Mosquito Coast to Jamaica, Porto Rico, and Cuba ; 

 and (2) the other through Trinidad to Anguilla, of the Wind- 

 ward Islands. He sustains the conclusion by a review of the 

 soundings made by the steamer ( Blake/ under the command of 



* An abstract of the paper is contained in Silliman's American Journal 

 [3] xviii. p. 230 (1880). 



