PACIFIC AND BEERING'S STRAIT. 255 



der it almost certain that the remainder also bad c ^f' 

 them in the early period of their formation, and that ^-v— 

 such is the peculiar structure of the coral islands. 18 26. 

 And, indeed, these exceptions can scarcely be con- 

 sidered objections, as two of them — Thrum Cap, 

 which is only seventeen hundred yards long by 

 twelve hundred broad; and Queen Charlotte's Island, 

 which is not more than three quarters of a mile wide 

 in its broadest part, and less than half a mile in other 

 places — are so circumstanced, that, had their lagoons 

 existed, they would have been filled in the course 

 of time with the masses of coral and other substances 

 which the sea heaps upon such formations as they 

 rise above the surface ; they have, besides, long been 

 wooded and inhabited, though deserted at the pre- 

 sent moment, both of which would tend to efface 

 the remains of a lagoon of such small dimensions. 

 The sea, however, prevented our boats from landing 

 upon either of these islands, to ascertain the fact of 

 the early existence of lagoons. The other exception, 

 Henderson's Island, though of coral formation, ap- 

 pears to have been raised to its present height above 

 the sea by a subterraneous convulsion, and has its 

 centre so incumbered and overgrown with bushes 

 that we could not determine whether it ever had a 

 lagoon. 



In the above-mentioned twenty-nine islands the 

 strips of dry coral enclosing the lagoons, divested of 

 any loose sandy materials heaped upon them, are 

 rarely elevated more than two feet above the level 

 of the sea ; and were it not for the abrupt descent 

 of the external margin, which causes the sea to break 

 upon it, these strips would be wholly inundated : 

 this height of two feet is continued over a small 



