Changes of Level in the Pacific Ocean. 253 



Matilda 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 

 subterranean action. 



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

 conclusive 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 de- 

 scriptions 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 en- 

 circling the island, may be evidence that a long period has 

 elapsed since the subsidence ceased ; and as such a change 

 is not common in the Pacific, we may suspect that it has 

 been furthered by at least a small amount of elevation. 

 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. 



Atiu (Wateoo of Cook) is a raised coral island. Cook ob- 

 serves that it is " nearly like Mangaia." The land near the 

 sea is only a bank of coral ten or twelve feet high, and steep 

 and rugged. The surface of the island is covered with ver- 

 dant hills and plains, with no streams. * 



* Cook's Voyage, vol. i., pp. 180, 197. Williams's Miss. Enterprizes, i., pp. 

 47, 48, first Am. edit., Appleton. 



