1839.] THE LAGOONS. 159 



son having already come on, the soil was found to be so 

 saturated with water, that very little progress could be made 

 in boring, after attaining a depth of twenty feet, and the 

 project was abandoned without arriving at any satisfactory 

 results. 



(4.) A remarkable peculiarity of the Paumotu Group, is 

 the existence of large and deep tunnel-shaped lagoons, con- 

 taining salt water, in the centre of most of the islands. Some- 

 times these are entirely isolated from the surrounding ocean, 

 and, at others, its waves break over the broken ramparts of 

 coral which appear here and there above the surface of the 

 water. Such of them as have, their pretty little lakes com- 

 pletely insulated, present a singularly picturesque appearance 

 when viewed from the mast-head of a vessel. In the centre 

 is the lagoon, — " deeply, beautifully blue," — neither disturbed 

 Dy the tempest whose sullen roar is heard amidst the neigh- 

 boring breakers, nor ruffled by the tossing surge rolled lazily 

 in upon the shore by the soft winds of the summer ; imme- 

 diately around this, is a strip of earth, — in some cases but a 

 few, and in others several hundred yards, in width, — covered 

 with a vegetation varying with the character of the island, 

 and either sparse or luxuriant, according to the nature and 

 depth of the soil ; and further beyond, extending to the brink 

 of the ocean, is a belt of white sand glistening like silver in the 

 perpendicular rays of the tropical sun. Within is the blue 

 turquoise, looking up to the bright heavens reflected from its 

 polished surface ; about it, is a gorgeous setting of emeralds ; 

 and the latter is, in turn, encircled by a rich chasing of 

 argent. 



Most of the islands are of a curvilinear form, and, with the 

 exception of Metia, which is a coral island uplifted, and sur- 

 rounded by a bold coralline shelf, rarely exceed twenty or 

 thirty feet in height. They are composed, at least near the 

 surface, of corallites, conglomerates, and limestone, above 

 which are coral debris, decayed vegetable matter, and guano, 

 with coral blocks occasionally cropping-out. The bottoms 

 and sides of the lagoons are lined with coral, and the shores, 



