174 CORAL-REEFS. 



and corals high up on the mountains of the Society Islands, 

 — a group encircled by barrier-reefs, and, therefore, sup- 

 posed to have subsided : at Tahiti Mr. Stutchbury found 

 on the apex of one of the highest mountains, between 5,000 

 and 7,000 feet above the level of the sea, "a distinct and 

 regular stratum of semi-fossil coral." At Tahiti, however, 

 other naturalists, as well as myself, have searched in vain at 

 a low level near the coast, for upraised shells or masses of 

 coral-reef, where if present they could hardly have been 

 overlooked. From this fact, I concluded that probably the 

 organic remains strewed high up on the surface of the land, 

 had originally been embedded in the volcanic strata, and 

 had subsequently been washed out by the rain. I have 

 since heard from the Rev. W. Ellis, that the remains which 

 he met with, were (as he believes) interstratified with an 

 argillaceous tuff; this likewise was the case with the shells 

 observed by the Rev. D. Tyerman at Huaheine. These 

 remains have not been specifically examined; they may, 

 therefore, and especially the stratum observed by Mr. 

 Stutchbury at an immense height, be contemporaneous with 

 the first formation of the Society Islands, and be of any 

 degree of antiquity ; or they may have been deposited at 

 some subsequent, but probably not very recent, period of 

 elevation ; for if the period had been recent, the entire sur- 

 face of the coast land of these islands, where the reefs are 

 so extensive, would have been coated with upraised coral, 

 which certainly is not the case. Two of the Harvey, or 

 Cook Islands, namely, Aitutaki and Manouai, are encircled 

 by reefs, which extend so far from the land, that I have 

 coloured them blue, although with much hesitation, as the 

 space within the reef is shallow, and the outline of the land 

 is not abrupt. These two islands consist of coral-rock ; but 

 I have no evidence of their recent elevation, besides, the 



