ELEVATIONS IN PACIFIC CORAL REGIONS. 287 



vessel were two hundred yards inside of the hne of breakers. 

 Captain Beechey suggests that the coral had grown, and tlius 

 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 an upheaval. 



b. TaJiitian Group. — The island of Tahiti presents no con- 

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

 on coral, which the mountain de'bris 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 confidendy believing 

 that any of them have been elevated. The change, however, 

 of the barrier reef around Bolabola into a verdant belt encir- 

 cling 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 fur- 

 thered by at least a small amount of elevation. The obser- 

 vation 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 (on 

 which island masses of coral are carried by natives up the 

 mountain, to leave at the highest point reached, and also to 

 mark the limits between the land of different chiefs, and are 

 common from these causes, up to a height of fifteen hundred 

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

 particular examination of the deposit. Moreover, shells, even 

 large ones, are carried far away from the sea by Hermit Crabs 

 (Pagurids). 



c. Hervey and Ruriitu Groups. — These groups lie to the 

 south-west and south of Tahiti. 



Afangaia is girted by an elevated coral reef three hundred 

 feet in height. Mr. Williams, in his Missionary Enterprises 

 pages 48, 50, and 249, speaks of it as coral, with a small quan- 

 tity of fine-grained basalt in the interior of the island ; he states 

 again that a broad ridge (the reef) girts the hills. 



