128 ON CORAL REEFS AND ISLANDS. 



Metia. — This island has already been described, and its eleva- 

 tion stated at two hundred and fifty feet. (See page 35.) 



Clermont Tonnerre* according to Mr. Couthouy, shows the 

 same evidence of elevation from Tridacnas as Honden Island. 

 Clermont Tonnerre and Honden are in the northeastern limits of 

 the Paumotus. 



Elizabeth Island was early shown to be an elevated coral isl- 

 and by Beechey. This distinguished voyager represents it as 

 having perpendicular cliffs fifty feet in height. From his descrip- 

 tion, it is obviously of the same character as Metia; the eleva- 

 tion is eighty feet. 



Dude's Island is described by Beechey as twelve feet high, 

 which would indicate an elevation of at least one or two feet. 



Osnaburgh Island, according to the same author, affords evi- 

 dence of having increased its height since the wreck of the Ma- 

 tilda in 1792. He contrasts the change from " a reef of rocks," 

 as reported by the crew, to " a conspicuously wooded island," the 

 condition when he visited it ; and states further, that the anchor, 

 iron- works, and a large gun (4-pounder) of this vessel were two 

 hundred yards inside of the line of breakers. Captain Beechey 

 suggests that the coral had grown, and thus increased the height. 

 But this process might have buried the anchor if the reef were 

 covered with growing corals, (which is improbable,) and could 

 not have raised its level. If there has been any increase of height, 

 (which we do not say is certain,) it must have arisen from sub- 

 terranean action. 



b. Tahitian Group. — The island of Tahiti presented us no con- 

 clusive evidence of elevation. The shore plains are said to rest 

 on coral, which the mountain debris has covered ; but they do 

 not appear to indicate a rise of the land. The descriptions by 

 different authors of the other islands of this group, do not give 

 sufficient reason for confidently believing that any of them have 

 been elevated. The change, however, of the barrier reef around 

 Bolabola into a verdant islet encircling the island, may be evi- 

 dence that a long period has elapsed since the subsidence ceased ; 

 and as such a change is not common in the Pacific, we may sus- 

 pect that it has been furthered by at least a small amount of ele- 

 vation. The observation by the Rev. D. Tyerman with regard 

 to the shells found at Huahine high above the sea, may be proof 

 of elevation ; but the earlier erroneous conclusions with regard 

 to Tahiti, teach us to be cautious in admitting it without a more 

 particular examination of the deposit. 



c. Hervey and Rurutu Groups. — These groups lie to the south- 

 west and south of Tahiti. 



* This island was not visited by the writer, as only the officers of the Yincennes 

 attempted to land on it. 



