176 
DISTRIBUTION 0? CORAL-REEFS. Cn. VI. 
tion is at present going forward at a very perceptible rate.’ 
The natives at Ivauai state that the land is there gaining 
rapidly on the sea ; and Mr. Couthouy has no doubt, from 
the nature of the strata, that this is the result of elevation. 
Elizabeth Island, in the southern part of the Low or 
Paumotu Archipelago, and Metia in the northern part, 
consist of upraised coral-rock, closely fringed by living 
reefs. 1 In cases like these, where islands have the appear- 
ance which one of the smaller surrounding atolls w 7 ith a 
shallow lagoon would present if elevated, we are led to con- 
clude that the elevation has taken place at an epoch not 
geologically remote ; for it is improbable that such small 
and low fabrics should have resisted for an immense period 
all the many destroying agents of nature. When the sur- 
face of an ordinary island is strewed with marine remains, 
from the beach to a certain height, and not above that 
height, it is exceedingly improbable that these remains, 
although they may not have been specifically examined, 
should belong to any very ancient period. It is necessary 
to bear these remarks in mind in considering the evidence 
of the elevatory movements in the Pacific and Indian 
Oceans, as it does not often rest on specific determinations, 
and therefore should be received with caution. Six of the 
Cook and Austral Islands (S.W. of the Society group) are 
fringed ; of these, five were described to me by the Eev. J. 
Williams, as formed of coral-rock (associated with some 
basalt in Mangaia), and the sixth as lofty and basaltic. 
Mangaia is nearly 300 feet high with a level summit ; and, 
according to Mr. S. Wilson, 2 is an upraised reef; ‘and 
there are in the central hollow, formerly the bed of the 
lagoon, many scattered patches of coral-rock, some of them 
raised to a height of forty feet.’ These knolls of coral-rock 
1 Beechey’s Voyage in the Pacific, p. 46, 4to edit. Dana, Corals 
and Coral Islands, p. 193. Wilkes, U.S. Exploring Expedition, vol. L 
p. 337. 
2 Couthouy’s Remarks, p. 34. 
