On. VI. DISTRIBUTION OF CORAL-REEFS. 
185 
mountains of the Society Islands,— a group of islands 
encircled by barrier-reefs, and which, therefore, must 
have recently subsided. Thus at Tahiti, Mr. Stutchbury 
found on the summit 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 ; ’ 
but we cannot infer from such evidence as this that the 
island has been elevated within the recent period ; and 
on the other hand, several naturalists, including Mr. 
Dana and myself, have in vain searched near the coast 
for upraised shells and corals, where if present they 
could not have been overlooked. 1 Two of the Harvey 
tion to these remains (vol. i. p. 38) and the tradition of the natives 
concerning them. See also Williams, Nar. of Miss. Enterprise, p. 
21 ; also Tyerman and G. Bennett, Journ. of Voyage, vol. i. p. 213 ; 
also Mr. Couthouy’s Remarks, p. 51 ; but his principal fact, namely, 
that there is a mass of upraised coral on the narrow peninsula ol 
Tiarubu, is from hearsay evidence ; also Mr. Stutchbury, West of 
England Journ. No. 1, p. 54. There is a passage in Von Zach, 
Corres. Astronom. vol. x. p. 2G6, inferring an uprising at Tahiti, 
from a footpath now used, which was formerly impassable ; but I 
particularly enquired from several native chiefs, whether they knew 
of any change of this kind, and they were unanimous in giving me an 
answer in the negative. 
' [Some of the mountains rise to 7,000 feet. A depth of 25 to 35 
fathoms, which is the limit of the growing corals, is reached at from 
100 to 150 fathoms from the edge of the reef. The slope then steepens 
rapidly to 1G0 and 180 fathoms, which depth is reached at a distance 
of 225 to 250 fathoms from the edge of the reef ; to 100 fathoms the 
slope is about 45°, thence to about 200 it is about 30°, and then it 
eases off. From 35 to 150 fathoms sponges, alcyonarians, corals, and 
other invertebrates were obtained ; beyond the latter, coral-sand with 
volcanic minerals and pelagic shells. Inside the lagoons the reefs 
were fringed with living corals, sloped downwards and outwards for 
a few feet, then plunged at once to depths of 10 and 1G fathoms. The 
deposit in the lagoons was in some places a coral-sand, in others a 
vclcanic mud. There is evidence of some amount of upheaval. 
