ELEVATIONS IN PACIFIC CORAL REGIONS. 333 



The most convenient mode of reviewing the subject is to 

 state in order, the facts relating to each group. 



a. Paumotu Archipelago. — The islands of this archipelago 

 appear in general to have that height which the ocean may 

 give to the materials. Nothing was detected indicating 

 any general elevation in progress through the archipelago. 

 The large extent of wooded land shows only that the islands 

 have been long at their present level ; and on this point the 

 author's observations confirm those of Mr. Darwin. There 

 are examples of elevation in particular islands, however, some 

 of which are of unusual interest. The instances examined by 

 the Expedition, are those of Honden Island (or Henuake), 

 Dean's Island (or Nairsa), Aurora (or Metia), and Clermont 

 Tonnerre. Besides these, Elizabeth Island has been described 

 by Beechey, and the same author mentions certain facts rela- 

 ting to Ducie's Island and Osnaburgh, which afford some sus- 

 picions of a rise. 



Honden Island or Henuake. — This island is wooded on its 

 different sides, and has a shallow lagoon. The beach is "eight 

 feet high, and the land about twelve. There are three entrances 

 to the lagoons, all of which were dry at low water, and one 

 only was filled at high water. Around the lagoon, near the 

 level of high tide, there were numerous deserted shells of the 

 huge Tridacna, often a foot long, lying in cavities in the coral 

 rock, precisely as they occur alive on the shore reef. As these 

 Tridacnas evidently lived where the shells remain, and do not 

 occur alive more than six or eight inches, or a foot at the most, 

 above low tide, they prove, in connection with the other facts, 

 an elevation of at least two feet. 



Nairsa or Dean's Island. — The south side of Dean's 

 Island, the largest of the Paumotus, was coasted along by the 

 Peacock, one of the Sloops of War of the Wilkes Exploring 



